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1. 10110B 8903E DISTORTION ANALYZER HP 10110B ADAPTOR UDIO SOURCE CENTER OUTPUT CONDUCTOR CABLE L EE Pens rg GROUND TERMINAL BRAIDED BINDING OUTER POST CONDUCTOR Figure 5 4 Common Mode Rejection Adjustment Test Setup Procedure 1 Switch the Distortion Analyzer off then back on to initialize it Set the Distortion Analyzer s INPUT switch to FLOAT 2 Set the audio oscillator to 1V at kHz The output impedance of the oscillator should be 6000 3 Connect the equipment as shown in Figure 5 4 Note how the cable center conductor and shield are connected to the Distortion Analyzer INPUT connector and ground terminal NOTE If desired the connections can also be made using a variety of adapters and jumper cables in place of the stripped coaxial cable 4 Adjust A2R43 CM for the minimum level on the right display but less than 0 2 mV 5 Perform the Common Mode Rejection Ratio Performance Test paragraph 4 13 es 8903 Adjustments ADJUSTMENTS 5 10 INPUT DC OFFSET ADJUSTMENT Reference Service Sheet 1 Description With the Distortion Analyzer set to measure dc level and the input grounded the dc offset is adjusted for a display of OV Equipment Feedthrough Termination 6000 HP 11095A Procedure Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch
2. 8903 Default Conditions and Sequence Description Related Sections 3 40 When first turned on the Distortion Analyzer performs a sequence of internal checks after which the instrument is ready to make measurements During the power up sequence all front panel indicators light to allow the operator to determine if any are defective After approximately four seconds this sequence is completed and the Distortion Analyzer is preset as follows MEASUREMENT AC LEVEL DETECTOR 2466s RR RR RMS LP FILTER LOW PASS 80 kHz HP Weighting BP Filter Off RATIO caera dad Off Ratio Reference 0 LOGULIN LIN see RATIO and LOG LIN Detailed Operating Instruction Left Display Input Frequency Right Display Input AC Level Service Request Condition HP IB Code Error Only Status Byte Cleared Trigger Mode Free Run Code TO Special Functions All Special Functions off or in their zero suffix except Service Request Condition which is set to 22 2 HP IB Code Error NOTE The FLOAT switch is set manually Ratio and LOG LIN Service Request Condition 8903 Description Procedure Example Program Code Indications Measurement Technique Comments Related Sections Operation Detector Selecti
3. 4 1 Abbreviated Performance Testing 4 1 PERFORMANCE TESTS 4 2 AC Level Accuracy 4 2 DC Level Accuracy 4 9 Residual Distortion and Noise 4 1 Distortion and SINAD Accuracy 4 12 Frequency Accuracy and Sensitivity 4 14 Audio Filters ENS RSS 4 15 Input Impedanc 4 22 Common Mode Rejection Ratio 4 24 Performance Test Record 4 26 8903 Section 5 ADJUSTMENTS Introduction usea mesi Safety Considerations Equipment Required Factory Selected Components Post Repair Tests Adjustments and Checks Related Adjustments ADJUSTMENTS Internal Reference Frequency Table of Contents CONTENTS cont d Page Input Flatness Common Mode Rejection Input DC Offset 400 Hz High Pass and Weighting Bandpass Filters Notch Filter Tune and Balance Voltmeter Using an HP IB Controller Voltmeter Not Requiring an HP IB Controller Vil Model 8903E as es se General Information Section 1 GENERAL INFORMATION 1 1 INTRODUCTION This manual c
4. nad am mab am cc OD OD m O O C O TT lt lt od oco mo s oof O Program Codes For HP IB codes refer to the Program Code table under Comments following 3 59 Operation Comments Related Sections 3 60 Model 8903E HP IB Address cont d Special Function 21 The HP IB address display is continuously updated This makes setting the address easy since the result of changing a switch setting is immediately visible on the display For information on setting the HP IB address of the Distortion Analyzer refer to Section 2 of this manual The factory set address is as shown in the examples decimal 28 The T and L bits are set to 0 The S bit powers up at 0 To clear the display from the instrument front panel press the LCL key then any function key The instrument reverts to the new measurement mode The HP IB address can also be displayed via Special Function 21 Since Special Functions can only be executed via HP IB the instrument s HP IB address must be known prior to its use The primary value of using HP IB is that the status of the Require Service message can be displayed To display the HP IB address via HP IB key in the appropriate HP IB program code as follows Display Pro
5. HP 8903B or HP 339A Controller with HP IB 85 Opt 007 Digital Voltmeter sius bed pews ease HP 3455A DIGITAL 8903E DISTORTION ANALYZER OSCILLATOR TEE Figure 5 6 Voltmeter Adjustment Test Setup Procedure NOTE The Distortion Analyzer s HP IB address is assumed to be 728 All HP IB commands are given in BASIC 1 Connect the HP IB controller to the Distortion Analyzer Key in and execute the following com mands OUTPUT 728 41 0SP 1 11SP 3 1SP OUTPUT 728 49 3SP Adjustments Model 8903E ADJUSTMENTS to initialize the instrument set the input range to 3V set the post notch amplifier gain to 0 dB and read the output rms detector voltage directly NOTE The above commands should not be concatenated A short waiting period between them is needed If the HP IB commands are to be put into a program insert a 200 ms wait between the two output statements Set the Distortion Analyzer s INPUT switch to ground Set the audio oscillator to at 1 kHz Connect the equipment as shown in Figure 5 6 Connect the voltmeter to A4TP1 DC OUT Set the voltmeter to read dc volts Adjust A4R125 DC CAL for a reading on the right display of the Distortion Analyzer that is the same as the reading on the voltmeter within 0 5 mV See Service Sheet 7 Connect the voltmeter to the INPUT of the Distortion Analyzer as shown in Figure 5 6 Set the vol
6. 3 10 Simplified Block Diagram 1 6 DO Level Check scu sever ti PUEDE 3 10 Voltmeter and Notch Filter 1 6 HP IB Functional Checks 3 11 UTERE NP 1 7 Address Recognition 3 11 Voltage Measurement 1 8 Remote and Local Messages and the LCL Key 3 12 Input Frequency Measurement 1 8 Sending the Data Message 3 18 1 8 Receiving the Data Message VES Basics of Audio Measurements 1 8 ud eee Clear OT 1 8 Local Messages ee eR ee DIEM eee at ear Message OF Frequency ee dd oe dcr Ue ee Suan ee eae 1 9 Abort Message 3 15 DC Level porc Reva Tete ee a 1 9 Status Byte Message 3 16 Signal Impurities ems 1 9 Require Service Message 3 17 Distortion 1 9 Trigger Message and Clear SINAD 1 10 Kev Triggering 4E Pest tan s 3 17 Table of Contents vi Model 8903 CONTENTS cont d Remote Operation Hewlett Packard Interface 2 HP IB Compatibility Remote Mod eee EC Remote Capability Local Mode inen Local Capability Remote to Local Mode Changes Addressing ue xr EAE See eus Local Lo
7. GENERAL Input Impedance 100 0 1 Except dc level mode DESCRIPTION An audio oscillator is connected to the Distortion Analyzer s input and a ratio reference is set A known impedance is then added in series with the input The drop in level is a measure of the output or input impedance The test is repeated with the audio oscillator connected to the analyzer s ungrounded outer conductor NOTE An arrangement of two BNC to clip lead adapters such as HP 8120 1292 and a male to male BNC adapter such as HP 1250 0216 provide a convenient way to insert the series resistor without stripping cables or soldering leads EQUIPMENT Audio HP 8903B or HP 3336C Dual Banana to BNC Adapter 10110B Dual Banana BNC Adapter 1251 2277 Resistor 1 OOK HP 0698 7497 PROCEDURE 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground 2 Set the audio oscillator to 3 Vrms at 100 Hz Connect the audio oscillator s output to the Distortion Analyzer s INPUT Press RATIO 3 Insert the 100kQ resistor in series with the center conductor of the audio oscillator s output The right display should read between 49 90 and 50 40 if the audio oscillator has 6000 output impedance or between 49 00 and 51 00 if the audio oscillator has 500 output impedance Display with 6000 Imped
8. Procedure To manually set the gain of the post notch circuit or to re enter the automatic selection mode enter the corresponding HP IB program code Program Code Post Notch Gain Automatic Selection 0 dB gain 20 dB gain 40 dB gain 60 dB gain Example To set the post notch gain to 40 dB lt gt 3 3SP TA IQ EE program codes Program Codes For HP IB codes refer to Procedure above Indications As the program code is entered it will flash on the left display the display then returns to show the input signal frequency Comments When the Distortion Analyzer is first powered up or when Automatic Operation is selected the Distortion Analyzer is placed in the automatic selection mode If the post notch gain is set such that the input signal level causes the post notch circuitry to be overdriven four dashes will be displayed on the right display If this overload condition is not corrected within nine measurement cycles Error 31 will be displayed Manually selecting the gain of the post notch circuit can cause measurement error Measurement accuracy is not specified whenever the gain of the post notch circuitry is manually selected because the selected gain setting may be less than optimum It is important to note that error messages indicating invalid measurements due to incorrect gain settings are not generated unless overload conditions occur Automatic operation ensures accurate measurements for all combination
9. AMPLIFIER D AC DC INPUT e ATTENUATOR INPUT HIGH AC DC INPUT LON COUNTER DE VOLTAGE EN AMPLIFIER Pe OVER VOLTAGE PROTECTION VOLTAGE TO TIME CONVERTER V T INPUT ATTENUATOR A VOLTMETER INPUT SELECTOR INSTRUMENT HARDWARE CONTROL KEYBOAAD AND DISPLAY Model 8903E 1 25 RECOMMENDED TEST EQUIPMENT Table 1 3 lists the test equipment recommended for use in testing adjusting and servicing the Distortion Analyzer If any of the recommended equipment is unavailable instruments with equivalent minimum specifications may be substituted Table 1 3 also in cludes some alternate equipment listings 1 26 PRINCIPLES OF OPERATION FOR SIMPLIFIED BLOCK DIAGRAM The Model 8903E Distortion Analyzer combines two instruments into one a general purpose voltmeter with a tunable notch filter at the input and a frequency counter Measurements are managed by a microprocessor based Controller This combination forms an instrument that can make most common measurements on audio circuits automatically To add to its versatility the Distortion Analyzer also has selectable input filters and HP IB programmability The operation of the instrument is described in the following order Voltmeter and Notch Filter Counter and Controller Refer to Figure 1 3 1 27 Voltmeter and Notch Filter The amplitude measurement path flows from the INPUT connector to the MONITOR output on the
10. OPERATOR S CHECKS Sending the Data Message NOTE OPERATOR S RESPONSE This check determines whether or not the Distortion Analyzer properly issues Data messages when addressed to talk This check assumes that the Distortion Analyzer is able to handshake and recognize its own address Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON then after the power up sequence is complete press the DISTN key wes Address the Distortion Analyzer to talk and red 728 V ENTER 728 V store its output data in variable V The out put is E96 since there is no signal at its INPUT Display the value of V PRINT V Check that the Distortion Analyzers REMOTE annunciator is off but that its AD DRESSED annunciator is on The controller s display should read 9009600000 00 HPL or 9009600000 BASIC Receiving the Data Message NOTE OPERATOR S RESPONSE This check determines whether or not the Distortion Analyzer properly receives Data messages The Data messages sent also cause the 7 least significant HP IB data lines to be placed in both their true and false states This check assumes the Distortion Analyzer is able to handshake recognize its own address and properly make the remote local transitions Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON Send the first part of the Remote message REMOTE 7 enabling the Distortion Analyzer to re
11. Table 3 1 Operating Characteristics Summary Operating Parameter Capabilities Input Limits Frequency 20 Hz to 100 kHz 150 kHz AC Level Level 0 to 300V ac or dc Impedance 100 except DC Level 101 DC Level floating input can Measurements including counter frequency be selected AC LEVEL 0 to 300 Vac 20 Hz to 150 kHz Full range display from measurements except in DC Level 3000 mV to 300 0V in seven ranges DC LEVEL 0 to 300 Vdc Full range display from 4 000V to 300 0V in four ranges SINAD 50 mV to 300V 20 Hz to 100 kHz Display range 0 to 99 99 dB DISTN 50 mV to 300V 20 Hz to 100 kHz Display range 99 99 to 0 dB Detection True rms or average detection Audio Filters HP BP FILTER Up to two of the following HP BP filters may be installed HIGH PASS 400 Hz 400 40 Hz 3 dB cutoff CCITT Weighting Recommendation P53 CCIR Weighting CCIR 468 2 DIN 45405 C MESSAGE BSTM 41009 FIG 1 A Weighting ANSI 81 4 IEC rec 179 DIN 45633 CCIR ARM Weighting Dolby Labs LP FILTER LOW PASS 30 kHz 30 2 kHz 3 dB cutoff 80 kHz 80 4 kHz 3 dB cutoff Manual Operation Average and rms detection notch tune ratio log linear filter selection and measurement selections can be manually controlled Remote Operation All Distortion Analyzer operations except the LINE and FLOAT switches can be controlled via the Hewlett Packard interface Bus Operation
12. gt a 2 0 5 2V 3V 10V 20 50V 100 200v 500 1000V 300V DIFFERENTIAL INPUT VOLTAGE CASE 1 Single Ended Source with Common Mode on Both Lines 3 37 Operation Model 8903E Common Mode cont d Comments cont d lt 5 e 5 i OPERATING REGION FOR S VALID MEASUREMENTS INSTRUMENT IN AUTOMATIC OPERATION 10 20mV 50mV 0 1V 0 2V 0 5V SOV 100V 200v 500V 1000V 300V DIFFERENTIAL INPUT VOLTAGE CASE 2 Balanced Source with Common Mode on Both Sides Related AC Level Sections DC Level 3 38 Mode 8903 Description Procedure Example Program Code Indications Measurement Technique Comments Related Sections Operation DC Level Pressing the DC LEVEL key causes the Distortion Analyzer to measure the differential dc voltage between the center and outer conductor of the INPUT connector or for Option 001 only the center conductors of the rear panel INPUT connectors Voltage common to both high and low inputs are rejected See the following Warning and Caution To avoid the possibility of hazardous shock on standard instruments those without Option 001 do not apply more than 42V peak to the outer conductor of the BNC INPUT connector when the FLOAT switch is in the FLOAT position lt CAUTION Do not apply more than 300 Vrms either differential common mode or a combination to the INPUT connector s
13. of bus commands is inhibited until the measurement is complete Once the measurement is complete bus commands will be processed as discussed under Trig ger Immediate above with no loss of data Thus in an HP IB environment where many bus commands are present Trigger Immediate or Trigger with Set tling should be used for failsafe operation Reading Data from the Right or Left Display The Distortion Analyzer can only read data to the HP IB once for each measurement made Only the informa tion on one display can be read each time Use the codes RR read right display or RL read left display to control which information is read The display wil remain selected until the opposing display is specified or until a clear message is received or power up occurs Errors which occupy two displays are output as described above and DC LEVEL measurement results always occupying the right display only are placed on the bus when requested regardless of which display is enabled Program Order Considerations Although program string syntax is virtually identical to keystroke order some program order considerations need highlighting Automatic Operation AU When Automatic Op eration is executed in remote only it sets all Special Functions prefixed 1 through 8 to their zero suffix mode and also affects many other Special Functions Thus when Automatic Operation is used it should appear at the beginning of a program string Trig
14. 10 3 4 Annunciators indicate remote operation Status LCL local key returns the Distortion Analyzer to keyboard control from remote HP IB control Frequency Display Annunciators indicate the frequency units MEASUREMENT CYCLE Indicator blinks after each measurement cycle The two Numeric Displays show the frequency measurement results error codes or instrument or Special Function status Measurement Display Annunciators indicate the measurement result units RATIO key causes measurements to be displayed in or dB relative to a reference LOG LIN key causes results to be displayed in loga rithmic or linear units MEASUREMENT keys command the Distortion Analyzer to make and display the selected measurement INPUT couples measurement signal into the instru ment 11 12 14 15 16 17 Model 8903E FLOAT switch provides floating input when required LOW PASS 30 kHz and 80 kHz filters reject high frequency noise RIGHT MOST OPTIONAL PLUG IN FILTER key se lects the filter that is installed in the right most filter slot The C Message Weighting bandpass Filter Option 053 shown weights receiver testing accord ing to BSTM 41004 LEFT MOST OPTIONAL PLUG IN FILTER key selects the filter that is installed in the left most filter slot The CCIR Weighting bandpass Filter Option 012 shown weights receiver testing according to CCIR
15. CCIR Weighting Filter Option 012 or 052 Deviation from Ideal Response 20 to 55 8096 relative humidity 1 kHz 60 Hz to 5 kHz C Message Weighting Filter Option 013 or 053 Deviation from Ideal Response 20 to 55 80 relative humidity 31 5 to 200 Hz 200 Hz to 6 3 kHz 6 3 kHz 6 3 to 7 1 kHz 7 1 to 10 kHz 10 to 20 kHz 20 to 31 5 kHz 1 See the International Telegraph and Telephone Consulative Committee CCITT Fifth Plenary Assembly 1972 Telephone Transmission Quality The International Telecommunication Union 1973 pp 87 91 CCITT Recommendation P53 2 See the International Radio Consultative Committee CCIR Recommendations and Reports of the CCIR 1978 Vol X pp 162 163 CCIR recommendation 409 3 3 See the Bell System Technical Reference 41009 May 1975 4 Dolby Laboratories Inc Engineering Field Bulletin No 19 4 CCIR ARM Weighting Filter Option 014 or 054 Deviation from Ideal Response Performance Tests Model 8903E PERFORMANCE TESTS Characteristic Performance Limits Conditions 1 AUDIO FILTERS Continued A Weighting Filter Option 015 or 055 20 to 55 80 relative humidity Deviation from Ideal Response 1 kHz 20 Hz to 10 kHz 10 to 20 kHz 5 See the American National Standard Specification for Sound Level Meters 1971 pp 8 10 American National Standard 1 4 1971 DESCRIPTION The output of the Distortio
16. However the program lines presented here would have to be modified for any other combination These checks are intended to be as independent of each other as possible Nevertheless the first four checks should be performed in order before other checks are selected Any special initialization or requirements for a check are described at its beginning INITIAL The test setup is the same for all of the checks Connect the Distortion Analyzer to the SETUP bus controller via the HP IB interface Do not connect any equipment to the Distortion Analyzer s INPUT EQUIPMENT HP IB Controller HP 9825A 98213A General and Extended I O ROM or HP 85B option 007 or HP 9000 Model 226 or any HP 9000 series 200 Computer Address Recognition NOTE This check determines whether or not the Distortion Analyzer recognizes when it is being addressed and when it is not This check assumes only that the Distortion Analyzer can properly handshake on the bus Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON Operation lt gt Model 8903E OPERATOR S CHECKS OPERATOR S RESPONSE OPERATOR S RESPONSE Set the Remote Enable REN bus control line false send the Distortion Analyzer s listen address LOCAL 7 OUTPUT 728 Check that the Distortion Analyzers REMOTE annunciator is off and that its AD DRESSED annunciator is on Unaddress the Distortion Ana
17. INTERNAL PROGRAMABLE PROGRAMABLE NOTCH GAIN AMPLIFIER GAIN AMPLIFIER FILTER TONITO LOW PASS FILTERS INPUT AMPLIFIER Monitor Output Block Diagram The MONITOR output gain and sensitivity that is the net signal gain from the INPUT to the MONITOR output are dependent on the input stage gain and the post notch gain Both the input stage gain and the post notch gain can be determined by viewing the Special Special Display refer to Special Functions The input stage gain and post notch gain for various instrument settings are listed in the tables below Model 8903 Operation Monitor Cont d Special Special Comments Cont d Input Level Range Display 1 NN Special Special 0 1 Display 20 10 3 N 40 100 60 1000 The measurement system net gain equals the combined gain of the two stages To calculate the net gain use the following formulas Net Gain LOG Input Stage Gain LOG Post Notch Gain LOG or Net Gain LIN Input Stage Gain LIN X Post Notch Gain LIN In ac level the MONITOR output is a scaled replica of the input signal The MONITOR output level is calculated as Mac Vax Net Gain where is the input signal level and the linear net gain is used 3 65 Operation Model 8903 Monitor Cont d Comments In SINAD distortion and distortion level the fundamental frequency is removed suppressed Cont d by more t
18. To make a dc level measurement press the S Shift key then the DC LEVEL key The voltage can be expressed in either volts or if the voltage is positive in dBm that is dB relative to 1 milliwatt into 6009 To obtain a display in dBm press the LOG LIN key To return to linear simply press the LOG LIN again If the dc level is to be displayed relative to a reference level refer to RATIO and LOG LIN To measure the dc level at the INPUT connector LOCAL keystrokes x program codes Measurement S1 is the HP IB code for DC LEVEL When dc level is selected the LEDs within the DC LEVEL key and the S Shift key will light The right display shows the dc level with the appropriate units The Distortion Analyzer automatically ranges for maximum resolution and accuracy In the dc level measurement mode the left display is blanked even though an ac signal may be present In the dc level measurement mode the Distortion Analyzer automatically sets the input attenuation and the gain of the input amplifier so that the signal amplitude lies within the proper range of the dc voltmeter The signal is then measured by the dc voltmeter and after correction for input gain and attenuation displayed in appropriate units In the dc level measurement mode only the ac component of the input signal is coupled to the MONITOR output The ac component also affects the input gain Common Mode RATIO and LOG LIN Special Functions 3 39
19. and Local messages When ad dressed to talk the Distortion Analyzer can issue the Data and Status Byte messages Whether addressed or not the Distortion Analyzer will respond to the Clear DCL Local Lockout Clear Lockout Set Operation Local and Abort messages and in addition the Distortion Analyzer may issue the Require Service message Local to Remote Mode Changes The Distortion Analyzer switches to remote operation upon receipt of the Remote message The Remote message has two parts They are Remote enable bus control line REN set true Device listen address received once while REN is true When the Distortion Analyzer switches to remote both the REMOTE and ADDRESSED annunciators on its front panel will turn on 3 15 Local Mode Local Capability In local the Distortion Analyzer s front panel controls are fully operational and the in strument will respond to the Remote message Whether addressed or not it will also respond to the Clear Local Lockout Clear Lockout Set Local and the Abort messages When addressed to talk the instrument can issue Data messages and the Status Byte message and whether addressed or not it can issue the Require Service message Remote to Local Mode Changes The Distortion Analyzer always switches to local from remote when ever it receives the Local message GTL or the Clear Lockout Set Local message The Clear Lockout Set Local message sets the Remote Enable contro
20. right display in form TLS where T 1 means talk only L 1 means listen only S 1 means SRQ Displays HP IB address in decimal Not Applicable Y Yes Except the LCL Keys Clear Key Function 3 82 Model 8903E Operation Special Function Summary 3 of 3 Function HP IB Diae x Description CLEAR NL Request 2 N Enable a condition to cause service request Except the LCL Shift and Numeric Keys The Clear Key Function References and Comments HP IB Service Request Condition N is the sum of any combination of the weighted conditions below 1 Data Ready 2 HP IB error 4 Instrument error The instrument powers up in the 22 2 state HP IB error Not Applicable Y Yes Procedure Entering Special Functions To use a special function enter the corresponding HP IB program code Special Display To display the user requested modes of Special Functions 1 through 8 press the S Shift key then the NOTCH TUNE key or enter the HP IB code SP The digit position noted beneath the displays corresponds to the special function prefix and the number displayed in that position corresponds to the special function suffix Special Special Display To determine the actual instrument settings of functions prefixed 1 through 8 press the S Shift key and the NOTCH TUNE key once while
21. the left display should be 4 Press AC LEVEL Press RATIO Set the ac calibrator frequency to 40 kHz Adjust A2C109 HIGH 40 DB for a reading on the right display between 99 70 and 100 3 Set the ac calibrator frequency to 100 kHz Adjust A2C109 for a reading between 99 50 and 100 5 Repeat steps 15 and 16 as often as needed until the flatness at 40 kHz and 100 kHz is within the limits given 5 5 Adjustments Model 8903E ADJUSTMENTS Low Input Flatness Adjustment 17 18 19 20 21 22 23 24 29 26 26 Set the ac calibrator to 1 kHz at 4 Vrms On the Distortion Analyzer set the INPUT switch to FLOAT Connect the equipment as shown in Figure 5 3 Note how the cable connects to the Distortion Analyzer s input through the two adapters The adapters reverse the outer and inner conductor connections to the cable 8903E DISTORTION ANALYZER GROUND INDICATOR Figure 5 3 Low Input Flatness Adjustment Test Setup Switch the Distortion Analyzer off then back on to initialize it Set LP FILTER off The right display of the Distortion Analyzer should read between 3 9 and 4 1V Check that the input is on range 10 by pressing S Shift NOTCH TUNE S Shift NOTCH TUNE The first two digits of the left display should be 10 Press AC LEVEL Press RATIO Set the ac calibrator frequency to 40 kHz Adjust A2C90 LOW 12 DB for a reading on the right display between 99 70 and 100 3 Set
22. 20 8903 Performance Tests PERFORMANCE TESTS 4 7 DC LEVEL ACCURACY PERFORMANCE TEST SPECIFICATION Characteristic Performance Limits Conditions DC LEVEL Accuracy 0 75 of reading 400 mV to 300V 3 mV lt 400 mV DESCRIPTION The output from standard is applied to the input of the Distortion Analyzer and the voltage on the display is compared against the output from the standard The procedure is run with the outer conductor of the input connector grounded then with the inner conductor grounded and the signal applied to the ungrounded outer conductor Voltages up to 300 will be applied to the Distortion A nalyzer s input connector EQUIPMENT DC Standard HP 740B Datron 4000 or Fluke 893AR PROCEDURE High Input DC Level Accuracy 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground Press S Shift DC LEVEL 2 Connect the output of the dc standard to the INPUT of the Distortion Analyzer 3 Set the dc standard to give the output voltage indicated below For each setting the right display on the Distortion Analyzer should read within the limits indicated DC Standard DC Voltage Limits Vdc Voltage Vdc Minimum Actual Maximum _ 300 30 3 0 4 0 04 Low Input DC Level Accuracy 4 On the Distortion Analyzer set the INPUT switch to FLOAT 5 Connect the equipment as shown in Figure 4
23. HP IB controlled only Post Notch Gain HP IB controlled only Read Display to HP IB HP IB controlled only Service Request Condition HP IB controlled only Special Functions HP IB controlled only Time Between Measurements HP IB controlled only amp Ro m 9 9 Y 4 9 o 73 97 uv 5 oy Po wo 9 a 9 9 3 P 8 9 9 a 4 9 9 o b 8 a e 4 e 9 9 gt Bo oo a 95 gt 6 He Fe e e a n o g o 9 59 9 ww 9 n b e 4 a 9 e 9 Be a HP IB HP IB Address Rapid Frequency Count Read Display to HP IB Service Request Condition 4 9 a on Goyan 4 5 e amp 9 9 5 Miscellaneous Automatic Operation Default Conditions and Power Up Sequence Float 9 a P5 o 9 9 9 9 9 9 B o 5 9 5 9 se O 8903 Operation HP IB Connector connects the Disto
24. LP Filter High Pass HP Bandpass BP optional AC Level Detection RMS 80 kHz Low Pass On off All Special Functions off or set to their zero suffix mode except Service Request Condition set to 22 2 HP IB code error Ratio Off Log Lin Linear Refer to RATIO and LOG LIN Detailed Operating Instructions Enabled HP IB Code Error Only Cleared Free Run Code TO Cleared plug in Filters Special Functions Right Display Read Service Request Condition Status Byte Trigger Mode Local Lockout 3 25 Operation ex 3 21 Receiving the Trigger Message When in remote and addressed to listen the Distortion Analyzer responds to a Trigger message by executing one settled measurement cycle The Distortion Analyzer responds equally to a Trigger message the Group Execute Trigger bus command and a Data message program code Trigger with Settling Refer to Triggering Measurements with the Data Message under paragraph 3 18 Receiv ing the Data Message 3 22 Receiving the Remote Message The Remote message has two parts First the remote enable bus control line REN is held true then the device listen address is sent by the controller These two actions combine to place the Distortion Analyzer in remote mode Thus the Distortion Analyzer is enabled to go into remote when the controller begins the Remote message but it does not actually switch to remote until addressed to listen the f
25. P O TWISTED PAIR WITH 11 P O TWISTED PAIR WITH 10 SRQ GROUND SHOULD BE GROUNDED j P O TWISTED PAIR WITH 9 IFC NEAR TERMINATION P O TWISTED PAIR WITH 8 NDAC OF OTHER WIRE OF P O TWISTED PAIR WITH 7 NRFD DAV EOI DIO 4 DIO 3 DIO 2 DIO 1 TWISTED PAIR P O TWISTED PAIR WITH 6 REN DIO 8 DIO 7 010 6 DIO 5 ISOMETRIC THREAD M3 5 x 0 6 24 PIN MICRO RIBBON SERIES 57 CONNECTOR Logic Levels The Hewlett Packard Interface Bus logic levels are TTL compatible that is the true 1 state is 0 0 to 0 4 Vdc and the false 0 state is 2 5 Vdc to 5 Vdc Programming and Output Data Format Refer to Section 3 Operation Mating Connector HP 1251 0293 Amphenol 57 30240 Mating Cables Available HP 10631A 1 meter 3 3 ft HP 10631B 2 meters 6 6 ft HP 10631C 4 meters 13 2 ft HP 10631D 0 5 meters 1 6 ft Cabling Restrictions 1 A Hewlett Packard Interface Bus system may contain no more than 2 meters 6 6 ft of connecting cable per instrument 2 The maximum accumulative length of connecting cable for any Hewlett Packard Interface Bus system is 20 meters 65 6 ft Figure 2 4 Hewlett Packard Interface Bus Connection x 2 6 8903 Operation Section 3 OPERATION 3 1 INTRODUCTION 3 2 General This section provides complete operating information for the Distortion Analyzer Included in this section are descriptions of all front and rear panel controls connectors
26. Sections 3 86 Model 8903E Time Between Measurements Special Function 14 A one second delay between measurements can be added using Special Function 14 It can be used to to allow the device under test to settle before making the measurement To add or delete the one second time delay between measurements enter the corresponding HP IB program code Time Delay Between Program Code Measurements x Minimum 14 0SP Add 1 second 14 1SP To set a one second time delay between measurements ux 14 1SP Code T Function program codes For HP IB codes refer to Procedure above As the program code is entered both displays will blank and the entered code will flash in the left display Both displays then return to the display that is appropriate for the currently selected measurement mode Automatic Operation Special Functions ES SS a es Model 8903E Performance Tests Section 4 PERFORMANCE TESTS 4 1 INTRODUCTION The procedures in this section test the instrument s electrical performance using the specifications of Table 1 1 as the performance standards All tests can be performed without access to the interior of the instrument A simpler operational test is included in Section 3 under Basic Functional Checks paragraph 3 10 The Basic Functional Checks also test the instrument s ability to function in the automatic mode which is not thoroughly checked by the Performance Tests NOTE Unle
27. The dc voltmeter measures both dc signals The controller then corrects for the programmed gain and attenuation computes the ratio of the two signals and displays the results in appropriate units The frequency of the input signal is also measured and displayed Distortion Measurement Block Diagram on next page 3 43 Operation Model 8903E Distortion cont d COUNTER LEFT OISPLAY FREQUENCY FREQUENCY MONITOR eure NOTCH MS AVE RMS AVG ATTENUATOR FILTER LP VOLTMETER RIGHT DISPLAY DETECTOR CONTROLLER AMPLITUDE NPUT FILTER 7 EIAS IN I PUT RMS AVG AMPLIFIER DETECTOR S N4D RANGING RMS DETECTOR Distortion Measurement Block Diagram Comments Distortion can be measured with either the true rms or average responding detector Most applications specify true rms detection Related Detector Selection Sections Distortion Level Filters Notch Tune RATIO and LOG LIN 3 44 Model 8903 Description Procedure Example Program Code Indications Measurement Technique Operation Distortion Level This measurement mode can be accessed only via HP IB The Distortion Analyzer measures the distortion level by removing the fundamental of the input signal and then measuring the ac level of the remaining noise and distortion The mV and V units are displayed in the linear mode or the values are converted to dBm that is dB relative to 1 milliwatt into a 6002 load The R
28. This code is ignored Hold Settings Hold input level ranges post notch gain decimal point and notch tuning at present settings Re enter Ratio Mode Restore last RATIO reference and enter RATIO mode if allowed Display RATIO reference Time Between Measurements Minimum time between measurements 14 0SP Add 1s between measurements 14 1SP SINAD Display Resolution 0 01 dB above 25 dB 16 0SP 0 5 dB below 25 dB 0 01 dB all ranges 16 1SP Display Level in Watts Display level as watts into 8Q 19 0SP Display level as watts into 19 NNNSP Read Display to HP IB Read right display 20 0SP Read left display 20 1SP HP IB Address 21 0SP Displays HP IB address in binary in left display right display in form TLS where 1 means talk only L 1 means listen only 821 means SRQ Displays HP IB address in decimal HP IB Service Request Condition Enable a Condition to cause a service request N is the sum of any combination of the weighted conditions below 1 Data Ready 2 HP IB error 4 Instrument error The instrument powers up in the 22 2 state HP IB error 3 31 Operation x 3 32 Oo Cn 5 00 000 000 00 000 001 00 000 010 00 000 011 00 000 100 00 000 101 00 000 110 00 000 111 00 001 000 00 001 001 00 001 010 00 001 011 00 001 100 00 001 101 00 001 110 00 001 111 00 010 000 00 010 001 00 010 010 00 010 011 00 010 100 00 010 101 00 01
29. the instrument must be made inoperative and be secured against any unin tended operation If this instrument is to be energized via an autotransformer for voltage reduction make sure the common terminal is connected to the earth terminal of the power source Servicing instructions are for use by service trained personnel only To avoid dangerous electric shock do not perform any servicing unless qualified to do so Adjustments described in the manual are per formed with power supplied to the instrument while protective covers are removed Energy available at many points may if contacted re sult in personal injury Capacitors inside the instrument may still be charged even if the instrument has been dis connected from its source of supply For continued protection against fire hazard replace the line fuse s only with 250V fuse s of the same current rating and type for exam ple normal blow time delay etc Do not use repaired fuses or short circuited fuseholders 111 Safety Considerations iv ATTENTION Static Sensitive Devices This instrument was constructed an ESD electro static dis charge protected environment This is because most of the semi conductor devices used in this instrument are susceptible to damage by static discharge Depending on the magnitude of the charge device substrates can be punctured or destroyed by contact or mere proximity of a static charge The results can
30. the table if the Distortion Analyzer is to meet its performance requirements 5 4 FACTORY SELECTED COMPONENTS Factory selected components are identified on the schematics and parts list by an asterisk which follows the reference designator The normal value or range of the components is shown The Manual Changes sup plement will provide updated information pertaining to the selected components Table 5 1 lists the reference designator the criteria used for selecting a particular value the normal value range and the service sheet where the component part is shown 5 5 POST REPAIR TESTS ADJUSTMENTS AND CHECKS Table 5 2 ists the performance tests adjustments and checks needed to calibrate or verify calibration of a repaired assembly The tests adjustments and checks are classified by assembly repaired The table is also useful as a cross reference between performance tests and assemblies when the failure is a specification that is slightly out of limits After all repairs perform the Basic Functional Checks paragraph 3 10 and the Internal Reference Frequency Adjustment paragraph 5 7 The Basic Functional Checks utilize automatic tuning and measurements which exercise nearly every circuit in the instrument except the Remote Inteface Assembly Adjustments Model 8903E 5 6 RELATED ADJUSTMENTS The procedures in this section can be done tn any order but it is advisable to check the time base reference first Table 5
31. 0 05 COS 2X vi SIN X AND 0 05 SIN 3X SIN X AND 0 05 COS 3X SIN X 0 05 SIN SIN X 0 05 COS 3X Figure 1 4 Several Waveforms Each With 5 THD and the Signal Components Which Produced Them 1 11 General Information Model 8903E Table 1 1 Specifications 1 of 4 All parameters describe performance in automatic operation or with properly set manual controls with a 12 hour warmup period MEASUREMENT SINAD Fundamental Frequency Range Display Range Accuracy Input Voltage Range Residual Noise and Distortion the higher of DISTORTION Fundamental Frequency Range Display Range Accuracy Input Voltage Range Residual Noise and Distortion the higher of AC LEVEL Full Range Display Overrange Accuracy DC LEVEL Full Range Display Overrange Accuracy 1 12 20 Hz to 100 kHz 0 to 99 99 dB 1 dB 2 dB 50 mV to 300V 80 dB 15 uV 70 dB or 45 65 dB or 45 uV 20 Hz to 100 kHz 0 001 to 100 99 99 to 0 dB 1 dB 2 dB 50 mV to 300V 80 dB or 15 V 70 dB or 45 uV 65 dB or 45 300 0V 30 00V 3 000V 3000V 30 00 mV 3 000 mV 3000 mV 33 2 4 4 300 0V 48 00V 16 00V 4 00V 33 1 0 of reading 6 mV 20 Hz to 20 kHz unfiltered or with low pass filters 20 kHz to 100 kHz 20 Hz to 20 kHz 80 kHz BW 20 Hz to 50 kHz 500 kHz BW 50 kHz to 100 kHz 500 kHz BW 20 Hz to 20 kHz unfiltered or with low pass filters
32. 1 1 ooo and Fuse Selection d ower Cables UNIT EET js HP IB Address Selection 2 2 udi icc DC C D MD D Interconnections 2 4 Description 5 4 46 teria 1 2 Mating Connectors 9 4 Gen E 1 2 Interface Connector 9 4 Audio Vestine bao eae act 1 2 Coaxial Connectors 2 4 Balanced Input ORT 1 2 Operating Environment 2 4 Transceiver Testing 1 3 Bench Operation ess YEN 2 5 Systeme RH Aa eae AR bie a 1 3 Hack Mounting gt 1 3 Storage and Shipment 2 5 Electrical Options 1 3 Environment 07 2 9 2 5 Electrical Option 001 1 3 Original Packagi 2 5 Internal Plug in Filter Options 1 3 ee e E CN D Other Packaging 2 5 Mechanical Options 1 4 Front Handle Kit Option 907 1 4 Section 3 Rack Flange Kit Option 908 1 4 OPERATION Rack Flange and Front Handle Introduction COMPE 3 1 Combination Kit Option 909 1 4 General ened outs du ravi eda
33. 50 000 100 000 100 000 100 000 j 4 30 Model 8903 Performance Tests Table 4 1 NEM NN Test Record 6 of 10 NEL m SINAD ACCURACY TEST Second Second Oscillator dB Readnpinstp3 in step 3 Low Distortion Oscillator Frequency NERONI Readings in step 4 200 000 10 100 000 200 000 60 100 000 100 000 100 000 300 000 60 300 000 10 4 31 Performance Tests Model 8903E Table 4 1 Performance Test Record 7 of 10 Para No Test Description FREQUENCY ACCURACY AND SENSITIVITY PERFORMANCE TEST Audio Input MEASUREMENT Mode Level Frequency mV Hz AC LEVEL DISTN DISTN AC LEVEL AC LEVEL AUDIO FILTERS PERFORMANCE TEST High Pass and Low Pass Filters Initial SOURCE Frequency Setting Hz 400 400 Hz HP 30 000 30 kHz LP 80 000 80 kHz LP 20 01 20 01 99 905 99 905 150 020 149 980 360 Hz 28 000 Hz 76 000 Hz 440 Hz 32 000 Hz 84 000 Hz Option 010 or 050 SOURCE Frequency Hz CCITT Weighting Filler Option 011 or 051 50 100 200 300 500 800 1 000 2 000 3 000 3 500 5 000 CCIR Weighting Filter Option 012 or 052 31 5 63 100 200 400 800 1 000 2 000 3 150 4 32 Model 8903E Performance Tests Table 4 1 Performance Test Record 8 of 10 AUDIO FILTE
34. Analyzer returns to local front panel control RL1 and local lockout is cleared when the REN bus control line goes false When entering local mode no instrument set tings or functions are changed but entries in progress are cleared In local triggering is free run only ET um The Distortion Analyzer sets the SRQ bus control line true if an invalid program code is received The Distortion Analyzer will also set SRQ true if enabled by the operator to do so when measurement data is ready or when an in strument error occurs Pass Control Take Control SRQ SR1 Require Service Commands Control lines and interface Functions are defined in IEEE Std 488 Knowledge of these might not be necessary if your controller s manual describes programming in terms of the twelve HP IB Messages shown in the left column 3 20 Model 8903 HP IB Message Applicable Yes Status Byte Operation x Table 3 3 Message Reference Table 2 of 2 Related Commands Interface and Functions Controls Response The Distortion Analyzer responds to a Serial Poll Enable T5 TEO SPE bus command by sending an 8 bit byte when ad dressed to talk If the instrument is holding the SRQ con trol line true issuing the Require Service message bit 7 RQS bit in the Status Byte and the bit representing the condition causing the Require Service message to be is sued will both be true The bits in the Status Byt
35. However with noisy input signals SINAD ratios less than 15 dB the signal is too noisy and unsettled for a good reading Consequently the notch filter jumps around trying to lock on to the input signal The resulting SINAD reading will probably be erroneous The following procedure will allow you to make stable SINAD measurements at any SINAD ratio First input a clean external source signal SINAD ratio greater than 20 dB with Notch Tune on automatic tuning NOTCH TUNE off Press S Shift SINAD This allows the Notch Filter to tune to the input frequency Freeze the notch filter by pressing the NOTCH TUNE key This locks the Notch Filter onto the input frequency Enter your desired signal to be measured SINAD less than 15 dB but at the same external source frequency The SINAD ratio measurement is read on the right display To select SINAD LOCAL NOTCH TUNE E keystrokes niue pc e ej B program codes Measurement __ Function M2 is the HP IB code for the SINAD measurement When the HP IB program code is entered both displays blank and four dashes are momentar ily displayed in the right display The displays then return to the normally displayed information for the currently selected measurement mode The LEDs in the DISTN SINAD and S keys light and the appropriate SINAD information for the input signal is displayed Model 8903E Operation SINAD cont d Measurement In the SINAD measurement mode t
36. IB The following discussion describes this function formode only Refer to Input Level Range Except DC Level for additionthe automatic operation mode the input level range is determined by both the dc and ac level if there is one of the input signal To set the input level range to a selected range or to re enter the automatic selection mode the corresponding HP IB program code Input Level Range Input Program Code Full Scale Attenuation HP IB Automatic Selection 300V range 64V range 16V range 4V range To set the input level range to the 16V range program codes For HP IB codes refer to Procedure above As the program code is entered it will flash on the left display which then temporarily blanks out Note that for all measurement modes except dc level the left display will return to show the input signal frequency after the HP IB code is entered When the Distortion Analyzer powers up or when Automatic Operation is selected the input level range is placed in the automatic selection mode If the input level range is set such that the input signal level causes the input overload detector to trip Error 30 will be displayed Manually selecting the gain of the input level circuitry can cause measurement error Measurement accuracy is not specified whenever the gain of the input level circuitry is manually selected because the selected gain setting may be less than optimum It is important to note tha
37. LIN key The right display should show 0 00 dB Filter Check 10 11 12 13 14 Adjust the frequency but not the level of the audio oscillator to approximately 80 kHz until the right display reads 3 dB The left display should show between 72 and 88 kHz Press the LOW PASS 30 kHz key The LOW PASS 30 kHz key light should light Adjust the frequency but not the level of the audio oscillator to approximately 30 kHz until the right display reads 3 dB The left display should show between 26 and 34 kHz Press the LOW PASS 30 kHz key again to turn it off Set the audio oscillator to 100 kHz The right display should show between 1 and 1 dB If the instrument has option 010 or 050 installed press 400 Hz HIGH PASS The 400 Hz HIGH PASS key light should light Adjust the frequency of the audio oscillator to approximately 400 Hz until the right display reads 3 dB The left display should show between 360 and 440 Hz Press the filter key listed in the following table for the filter option installed in the instrument The respective key hght should light For each filter set the audio oscillator frequency as shown in the following tables Verify that the level ratio in the right display is within the limits shown for each frequency Table for CCITT Weighting Filter Option O11 or 051 Oscillator Frequency Hz Ratio Limits dB 12 1 to 0 4 to 7 1 to 11 5 to 40 0 to Table for CCIR
38. Measurements AC Level Common Mode DC Level Detector Selection Distortion Distortion Level HP IB controlled only SINAD oa Ro B a 5 amp nmn b 59 Fe P P B B e 9 9 9 9 5 e a 9 9 9 92 R FE Aa 9g 5 Nw m P a 4 P 9 7 Filters Filters Low Pass High Pass Bandpass Notch Tune Post Notch Detector Filtering Data Manipulation Display Level in Watts HP IB controlled only Hold Decimal Point HP IB controlled only Ratio and Log Linear eee 9 Errors Error Disable Error Message Summary He 9 9 c8 9 Inputs and Outputs Float Monitor g 4 b BP P n 9 9 9 amp m 3 6 Page Section Special Functions Detector Selection Display Level in Watts HP IB controlled only Error Disable Hold Decimal Point HP IB controlled only Hold Settings HP IB controlled only HP IB Address Input Level Range DC Level HP IB controlled only Input Level Range Except DC Level HP IB controlled only Notch Tune Post Notch Detector Filtering
39. Recommendation 468 2 DIN 45405 NOTCH TUNE key switches the Notch Filter tune control between Auto Tuned and Hold mode locking the Notch Filter at its current frequency setting MONITOR OUTPUT in ac level mode provides a scaled voltage output representing the input signal In SINAD distortion and distortion level modes provides a scaled voltage output of the input signal with fundamental removed Output impedance is 6000 LINE switch applies power to the Distortion Analyzer when set to ON Figure 3 1 Front Panel Features Model 8903 Operation SIMPLIFIED OPERATION Measurement For ac level or distortion measurements press For dc level and SINAD measurements press Filters HP BP Filter Corresponding Filter To activate any of the optional plug in filters press LP Filter LOW PASS 30 To activate the LOW PASS 30 kHz filter press RATIO and LOG LIN RATIO To set the displayed measurement as the ratio reference press Jaro LOG LIN To convert from linear to logarithmic or from logarithmic to linear measurement units press Jase RATIO on RATIO off Measurement AC LEVEL dBm into 6002 DC LEVEL dBm into 6009 SINAD dB DISTN dB NOTE During power up the Distortion Analyzer is initialized and set to automatic operation 3 5 Operation Model 8903 Table 3 2 Detailed Operating Instructions Table of Contents Functional Listing Section
40. Special Display is active or enter the HP IB code SS If the Special Display described above is not in effect press the above mentioned keys twice to get this display The digit position corresponds to the function prefix and the number displayed in that digit corresponds to the function suffix Examples Entering Special Functions To set the post notch gain to 40 dB lt gt program codes Special Display When the S Shift and NOTCH TUNE keys are pressed the following display results SUFFIXES PREFIXES 1 2 3 4 5 6 7 8 3 83 Operation Model 8903E Special Functions Cont d Examples This display indicates that the following Special Functions were selected by the operator cont d Special Function User Requested Setting Input Level Range Except DC Level 0 189V range Input Level Range DC Level only Automatic Selection Post Notch Gain Automatic Selection Hold Decimal Point DD DD mV range right display only Post Notch Detector Fast RMS Detector Filtering Except in SINAD Notch Tune Hold notch tuning Error Disable Disable analyzer errors Special Special Display When the S Shift and NOTCH TUNE keys are pressed again while the Special Display is active and the following display results the actual instrument settings are tabulated below SUFFIXES PREFIXES 1 2 3 4 5 6 7 8 Actual Instrument Setting Input Level Range Except DC Level 0 189V range Input Level Range DC Le
41. This product has autoranging line voltage input be sure the supply voltage is within the specified range Chapter 1 3 a Regulatory Information Updated March 1999 To prevent electrical shock disconnect instrument from mains line before cleaning Use a dry cloth or one slightly dampened with water to clean the external case parts Do not attempt to clean internally Ventilation Requirements When installing the product in a cabinet the convection into and out of the product must not be restricted The ambient temperature outside the cabinet must be less than the maximum operating temperature of the product by 4 C for every 100 watts dissipated in the cabinet If the total power dissipated in the cabinet is greater than 800 watts then forced convection must be used Product Markings CE the CE mark is a registered trademark of the European Community A CE mark accompanied by a year indicated the year the design was proven CSA the CSA mark is a registered trademark of the Canadian Standards Association 4 Chapter 1 Model 8903 Safety Considerations SAFETY CONSIDERATIONS GENERAL This product and related documentation must be re viewed for familiarization with safety markings and instructions before operation This product is a Safety Class I instrument provided with a protective earth terminal BEFORE APPLYING POWER Verify that the product is set to match the available line voltage and t
42. be 726 All HP IB commands are given in BASIC High Level High input AC Level Accuracy 1 Connect the HP IB controller to the Distortion Analyzer Key in and execute the following command OUTPUT 728 41 0SP LO to initialize the instrument and set the 80 kHz LOW PASS filter off NOTE If a controller is not being used switch the Distortion Analyzer to off then back on After power up press the 60 kHz LOW PASS to turn it off 4 2 8903 Performance Tests PERFORMANCE TESTS ae ca d 2 Set the Distortion Analyzer s INPUT switch to ground Connect the ac calibrator to the Distortion Ana lyzer s INPUT 3 Set the ac calibrator to the level indicated in the table Use the high voltage amplifier where needed Using the controller key in and execute the Special Function and ratio commands indicated in the table below Now set the ac calibrator to the frequency indicated in the table The right display of the Distortion Analyzer should read within the limits indicated NOTE If a controller is not being used proceed as follows a Set the ac calibrator level and frequency as indicated b Press S Shift NOTCH TUNE S Shift NOTCH TUNE In the left display the digit or digits displayed in position 1 and the digit preceding it if not blanked should agree with the Special Function suffix of the controller command in the table For example the display for 1 2SP should 2 in position 1 the preced
43. can be prevented by disabling the Distortion Analyzer s front panel keys entirely using the Local Lockout message 3 26 Model 8903E 3 24 Receiving the Local Lockout Message The Local Lockout message is the means by which the controller sends the Local Lockout LLO bus command If in remote the Distortion Analyzer re sponds to the Local Lockout Message by disabling the front panel LCL local key and the Clear Key Function In remote the Clear Key Function initiates a Trigger with Settling cycle The local lockout mode prevents loss of data or system control due to someone accidentally pressing front panel keys If while in local the Distortion Analyzer is enabled to remote that is REN is set true and it receives the Local Lockout message it will switch to remote mode with local lockout the first time it is addressed to listen When in local lockout the Distortion Analyzer can be returned to local only by the controller using the Local or Clear Lockout Set Local messages or by setting the LINE switch to OFF and back to ON or by removing the bus cable 3 25 Receiving the Clear Lockout Set Local Message The Clear Lockout Set Local message is the means by which the controller sets the Remote Enable REN bus control line false The Distortion Analyzer returns to local mode full front panel control when it receives the Clear Lockout Set Local message No instrument settings are changed by the transition from re
44. cause degradation of device performance early failure or immediate destruction These charges are generated in numerous ways such as simple con tact separation of materials and normal motions of persons working with static sensitive devices When handling or servicing equipment containing static sensitive devices adequate precautions must be taken to prevent device dam age or destruction Only those who are thoroughly familiar with industry accepted techniques for handling static sensitive devices should attempt to service circuitry with these devices In all instances measures must be taken to prevent static charge build up on work surfaces and persons handling the devices For further information on ESD precautions refer to SPECIAL HANDLING CONSIDERATIONS FOR STATIC SENSITIVE DEVICES in Section VII Service Section Model 8903E ___ eee Model 8903 Table of Contents CONTENTS VOLUME 1 Page Page Section 1 Section 2 GENERAL INFORMATION INSTALLATION Introductio x eut exiens 1 1 IntrodUCtioH du E MANT DESI 2 1 SDecIBcAlloHS uu bob by eR UU ee De aero iei 1 1 Initial Inspection 2 1 Safety Considerations 1 1 Preparation for Use 2 Instruments Covered by Manual 1 1 Power Requirements pe ne e enne 2 1 Serial Numbers
45. connector c Remove the Distortion Analyzer top cover 1 Remove the two plastic feet from the rear of the top cover by removing the panhead Pozi driv screw within each foot 2 Unscrew the Pozidriv screw at the center of the rear edge of the top cover This is a captive screw and will cause the top cover to pull away from the front frame 3 Lift off the top cover To avoid the possibility of hazardous electrical shock do not operate this instrument at line voltages greater than 126 5 Vac with line fre quencies greater than 66 Hz leakage currents at these line settings may exceed 3 5 mA Open cover door pull the FUSE PULL lever and rotate to left Remove the fuse Remove the Line Voltage Selection Card Position the card so the line voltage appears at top left cover Push the card firmly into the slot Rotate the Fuse Pull lever to its normal position Insert a fuse of the correct value in the holder Close the cover door Figure 2 1 Line Voltage and Fuse Selection 2 2 Model 8903 Installation Cable Cable For Use 250V 8120 1351 Mint Gray United Kingdom 8120 1703 Mint Gray Cyprus Nigeria Rhodesia L N 250V 8120 1369 8120 0696 250V 8120 1689 8120 1692 Cable Length inches Plug Description Straight BS1363A 90 Singapore Straight NZSS198 ASC112 90 Australia New Zealand Straight CEE7 Y
46. detector Set the audio oscillator amplitude to 2 5V and key in S Shift NOTCH TUNE S Shift NOTCH TUNE The left display should read 11214 NOTE Do not press any additional keys until step 12 This display must present through step 11 Set the audio oscillator amplitude to Adjust A4R93 AVG SCALE for a reading on voltmeter that is the same as the reading on voltmeter A within 1 mV See Service Sheet 6 Set the audio oscillator to 150 mV Adjust A4R149 AVG OFFSET for a reading on voltmeter B that is the same as the reading on voltmeter within 0 5 mV See Service Sheet 6 Set the audio oscillator amplitude to 3V Repeat steps 9 and 10 until the readings for voltmeter A and voltmeter B agree within the limits stated for both 3V and 150 mV Press AC LEVEL Set the audio oscillator to at kHz Leave the Distortion Analyzer s detector in average Adjust 4 125 DC CAL until the right display of the Distortion Analyzer and voltmeter B agree within 0 5 mV
47. entry is given below followed by several examples illustrating various entries and the resulting data as received by the Distortion Analyzer General Numeric Data Input Format 00000 5 Digit Spica rm Magnitude Mantissa Indicates Exponent Follows Exponent Sign Example 12345E 01 issued 0 12340E 01 received by Distortion Analyzer Example 123456E 01 issued Example 123450E 01 received by Distortion Analyzer Example 00012345 issued 12000 Example received by Distortion Analyzer Example In general do not issue numeric data with more significant digits than can be displayed on the Distortion Analyzer s five digit left display Operation x Triggering Measurements with the Data Message feature that is only available via remote program ming is the selection of free run standby or triggered operation of the Distortion Analyzer During local operation the Distortion Analyzer is allowed to free run outputting data to the display as each measurement is completed In remote three addi tional operating modes are allowed Hold Trigger Immediate and Trigger with Settling In addition the Clear Key Function can act as a manual trigger while the instrument is in remote The trigger modes and use of the Clear Key Function are described below Free Run TO This mode is identical to local operation and is the mode of operation in effect when no other trigger mode has been selected
48. exceed 42V peak in the FLOAT mode In single ended FLOAT switch in grounded position or differential FLOAT switch in FLOAT position operation the input signal voltage is not to exceed 300V when referenced to ground on the high INPUT connector inside conductor of the BNC In differential FLOAT switch in FLOAT position operation the peak voltage on the low INPUT connector outer conductor of the BNC is not to exceed 42V Pa Paha Foe te Paro pase Pasa Ph T CAUTION Cis ia de da a aia da to Before the Distortion Analyzer is switched on it must be set to the voltage of the power source or damage to the instrument may result If the Distortion Analyzer is already plugged in set the LINE switch to ON If the power cable is not plugged in follow these instructions 1 Check that the line voltage setting matches the power source see Figure 2 1 2 Check that the fuse rating is appropriate for the line voltage used see Figure 2 1 Fuse Ratings are given under paragraph 3 8 Operator s Maintenance 3 Plug in the power cable 4 Set the LINE switch to ON NOTE When the LINE switch is set to ON all front panel indicators will light for approx imately 4 seconds after which the instru ment 15 ready to be operated 3 5 Local Operation Information covering front panel operation of the Distortion Analyzer is given in the sections described below To rapidly learn the operation of the ins
49. higher than at 40 kHz decrease A2C 102 by approximately 10 If the 40 kHz reading is higher than that at 100 kHz increase A2C 102 by approximately 10 29 On the Distortion Analyzer press RATIO to turn it off 30 Set the ac calibrator frequency to 1 kHz and level to 60 Vrms 31 The right display of the Distortion Analyzer should read between 58 8 and 61 2V Check that the input is on range 4 by pressing S Shift NOTCH TUNE S Shift NOTCH TUNE The first digit of the left display should be 4 Press AC LEVEL Press RATIO 32 Set the ac calibrator frequency to 40 kHz Adjust A2C110 HIGH 40 DB for a reading on the right display between 99 70 and 100 3 33 Set the ac calibrator frequency to 100 kHz Adjust A2C110 for a reading between 99 50 and 100 5 Repeat steps 32 and 33 as often as needed until the flatness at 40 kHz and 100 kHz is within the limits given 34 Perform the AC Level Accuracy Performance Test paragraph 4 6 5 7 Adjustments Model 8903E ADJUSTMENTS 5 9 COMMON MODE REJECTION ADJUSTMENT Reference Service Sheet 1 Description An audio oscillator set to 1 Vrms at kHz is connected to both the high and low that is the inner and outer conductor inputs of the Distortion Analyzer The low input is set to float The common mode ac level is then adjusted for minimum response Equipment Audio HP 8903B or HP 3336C Dual Banana to BNC
50. level using an external voltmeter with a very flat frequency response then the level of the second oscillator is attenuated to obtain a precise ratio EQUIPMENT Audio Oscillator Low Distortion HP 339A or HP 8903B Audio Oscillator oreca rier Ern EN DRE AS SS RAS HP 3336C True RMS Voltmeter HP 3403C PROCEDURE 1 Switch the Distortion Analyzer off then back on to initialize it Set the Distortion Analyzer controls as follows INPUT Switch 23 3 ected vba reb e E ground MEASUREMENT uo Rr o Raus DISTN LOGELIN LOG 2 Connect the equipment as shown in Figure 4 3 The output impedance of both oscillators should be 502 Set the voltmeter to read ac volts Set the output of the low distortion oscillator to 6V into an open circuit 8903E DISTORTION ANALYZER SECOND AUDIO OSCILLATOR OUTPUT LOW DISTORT ION AUDIO OSCILLATOR 50 OHM FEEDTHROUGH TERMINATION Figure 4 3 Distortion and SINAD Accuracy Test Setup 8903 Performance Tests PERFORMANCE TESTS 3 Set the oscillator frequencies as indicated below For each frequency setting perform the following pro cedure a Set the second oscillator level to minimum Note the level of the output of the low distortion oscil lator on the external voltmeter b Set the low distortion oscillator amplitude to OV Adjust the second oscillator s level for the same reading as in step a c Decr
51. measurements 1 x HP IB Not just IEEE 488 but the hardware documentation and support that delivers the shortest path to a measurement system Model 8903 RESIDUAL DISTORTION and NOISE dB 20 Hz 50 Hz 200 Hz 500 Hz 2 kHz 5 kHz 20 kHz FREQUENCY Figure 1 1 Typical Analyzer Residual Distortion 1 9 Transceiver Testing The Distortion Analyzer has several measurements and features specifically designed for transceiver test ing It has SINAD measurements for receiver testing optional internal plug in weighting filters for testing to international standards a reciprocal counter for measuring squelch tones and an optional internal plug in 400 Hz high pass filter for eliminating squelch tones when measuring transmitter audio distortion SINAD is one of the most basic receiver measure ments It must be made repeatedly when performing sensitivity or adjacent channel sensitivity tests In the Distortion Analyzer the SINAD measurement is more heavily filtered than the distortion measurement in order to smooth the noisy signals encountered in receiver testing The filtering is optimized for excel lent repeatability and speed 2 readings second typ ical Some automatic distortion analyzers have a tendency to become untuned when measuring SINAD on noisy signals The Distortion Analyzer overcomes this problem by providing a front panel key which locks the notch filter at the input frequency For SIN
52. of input signals and measurement modes Related Automatic Operation Sections Monitor Special Functions 3 69 Operation Model 8903E Rapid Frequency Count Rapid Frequency Count mode allows a remote controller to partially bypass the Distortion Analyzer s own internal controller The advantage is that frequency count measurements can then be obtained from the Distortion Analyzer much more quickly The data obtained however is in a packed binary form and thus requires additional processing to produce the final results in hertz Hz Once the Rapid Frequency Count mode is entered data will be placed on the bus in four byte sequences until the mode is terminated Rapid Frequency Count mode is terminated whenever the Distortion Analyzer receives a bus command or whenever it is sent new programming data Description Procedure To use the Rapid Frequency Count mode the remote controller must be able to read the four byte compacted frequency data using a binary specifier First place the Distortion Analyzer into the ac level measurement mode set it to measure the input signal that is the signal before the notch filter and to trigger with settling The HP IB codes for this configuration are M146 1SPT3 Next issue the HP IB code for Rapid Frequency Count RF and then read the frequency data from the Distortion Analyzer The Distortion Analyzer does not send carriage return line feed or any other characters as delimiters The
53. provides the information required to repair the instrument Sections 1 through 5 are bound in this volume the Operation and Calibration Manual Sections 6 through 8 are bound in two separate volumes the Service Man ual The Service Manual is comprised of an HP 8903E Service Supplement and an HP 8903B Service Manual Copies of the Service Manual are not supplied with the instrument unless specifically requested as option 915 at time of instrument order The Operation and Calibration Manual is supplied with the instrument order When option 915 is requested the complete service manual the HP 8903E Service Supplement and the HP 8903B Service Manual is supplied with the instrument order Copies of all volumes can be ordered through your nearest Hewlett Packard sales office The part num bers are listed on the title page of this manual Also listed on the title page of this manual below the manual part number is a microfiche part number This number may be used to order 100 150 mm 4 X 6 inch microfilm transparencies of this manual Each microfiche contains up to 96 photo duplicates of the manual s pages The microfiche package also includes the latest MANUAL CHANGES supple ments as well as all pertinent Service Notes 1 2 SPECIFICATIONS Instrument specifications are listed in Table 1 1 These are the performance standards or limits against which the instrument may be tested Characteristics listed under Supplementa
54. ratio reference value refer to RATIO and LOG LIN A distortion measurement can be made on signals from 20 Hz to 100 kHz and from 50 mV to 300V in the single ended mode FLOAT switch in the grounded position To make a distortion measurement press the DISTN key Use the filters to limit noise hum spurious signals etc The Distortion Analyzer powers up with the LOW PASS 80 kHz filter activated To measure the distortion of an external source in a 30 kHz bandwidth m M3L1 program codes E 3 jis Filter M3 is the HP IB code for the distortion measurement When distortion is selected the LED within the DISTN key will light The frequency and distortion of the input signal are displayed and the appropriate annunciators are lighted see Description above In the distortion measurement mode the controller automatically sets the input attenuation and the gain settings of various amplifiers This is accomplished by measuring the input signal with the ranging rms detector This control ensures that the signal amplitude is within the proper range for the input and output detectors The Input RMS AVG Detector converts the ac level of the combined signal noise distortion to dc The notch filter removes the fundamental signal The notch filter automatically tunes to the component whose frequency is measured by the counter usually the fundamental of the input signal The output detector converts the residual noise distortion to dc
55. the Detailed Operating Instructions and provides a 3 2 A l AA Model 8903E basis for applying the Distortion Analyzer to various measurement situations Basics of Audio Measure ments is a general discussion of audio measurements It is intended to provide an intuitive understanding of audio measurements rather than an in depth math ematical analysis 3 6 Remote Operation 42E The Distortion Analyzer is capable of remote opera tion via the Hewlett Packard Interface Bus HP IB Instructions pertinent to HP IB operation cover all considerations and instructions specific to remote op eration including capabilities addressing input and output formats the status byte and service requests At the end of the discussion is a complete summary of all codes and formats In addition to the section described above informa tion concerning remote operation appears in several other locations HP IB Address selection is discussed under paragraph 2 7 in Section 2 Numerous examples of program strings appear throughout the Detailed Operating Instructions described under Local Opera tion above 3 7 Operator s Checks Operator s checks are procedures designed to verify the proper operation of the Distortion Analyzer s main functions Two procedures are provided as de scribed below Basic Functional Checks This procedure requires an audio oscillator oscilloscope and inter connecting cables It assumes that most front panel
56. the common mode input is then measured for two different input ranges EQUIPMENT Audio HP 8903B or HP 3336C Controller with HP IB HP 85B Opt 007 Dual Banana to BNC Adapter HP 10110B B903E DISTORTION ANALYZER OUTPUT AUDIO OSCILLATOR HP 101108 ADAPTOR ae AUDIO BNC CONNECTOR CENTER OUTPUT CONDUCTOR CABLE FA KEEN ES Mea GROUND a TERMINAL BRAIDED BINDING OUTER POST CONDUCTOR Figure 4 5 Common Mode Rejection Ratio Test Setup PROCEDURE NOTE The Distortion Analyzer s HP IB address is assumed to be 726 All HP IB commands are given in BASIC 1 Connect the HP IB controller to the Distortion Analyzer Key in and execute the following command OUTPUT 728 41 0SP to initialize the instrument Set the Distortion Analyzer s INPUT switch to FLOAT EXEC a gt gt gt AC INC EDEN RI TIE I TT TE DU ICM ML A EN E I 4 24 8903 Performance Tests PERFORMANCE TESTS 2 Set the audio oscillator to 1 at 20 Hz The output impedance of the oscillator should be 6000 3 Connect the equipment as shown in Figure 4 5 Note the use of the dual banana to BNC adapters to tie the inner and outer conductors of the input connector together NOTE If desired the connections
57. the counter Refer to Service Sheet 14 Cannot confirm external This error indicates that in notch routine the frequency source frequency could not be measured and thus the notch could not be adjusted This usually indicates a counter problem Refer to Service Sheet 14 RATIO not allowed in This error code indicates that use of the RATIO key present mode does not make sense in the current mode Refer to RATIO and LOG LIN 3 49 Model 8903 Error Message Summary cont d Error Error Messages Action Required Comments cont d Operating Errors Cont d Input overload detector This error code indicates that the input signal is too tripped in range hold high for the selected range Use Special Function 1 to enter a more realistic range setting or enter AU over the HP IB to allow the Distortion Analyzer to seek the correct input range Refer to Automatic Operation Cannot make This error code indication occurs when the input signal measurement is changing too quickly for the Distortion Analyzer to make consistent measurements or when the common mode signal is too large for the Distortion Analyzer The display indicates that the instrument is trying to make a measurement After nine unsuccessful tries Error 31 is displayed HP IB only No signal This error is sent on the HP IB when the display sensed at input is shown Entered value out ee Re enter new value range Invali
58. the float mode the center conductor is the High Input and the outer conductor is the Low Input that is isolated from chassis ground In the single ended mode the FLOAT switch in the grounded position the outer conductor is connected directly to chassis ground The INPUT BNC connector allows the attachment of a shielded cable in the single ended mode which minimizes electromagnetic interference EMI This is important if the Distortion Analyzer is operated near a transmitter or in the presence of large RF signals When the FLOAT switch is in the grounded position the outer conductor of the connector is connected to chassis ground If EMI shielding is not critical banana type connectors can be used For Option 001 two BNC to banana adapters are supplied with the instrument to convert the BNC input and output to dual banana with standard 34 inch spacing The adapters connect the conductor of the banana connector to the center conductor of the BNC connector These adapters are normally used when the FLOAT switches are set in the FLOAT position DEVICE UNDER TEST COMMON CONDUCTOA LINE RESISTANCE Effect of Multipoint Ground System FLOAT Switch Closed 3 59 Operation Comments cont d 3 06 Model 8903E Float cont d One major source of error which must be considered when measuring low level ac signals or when making low distortion measurements is error introduced by ground loops The figure above illustra
59. the internal plug in HP BP Filters General Information When measuring SINAD distortion or distortion level the fundamental of the signal is removed by the Notch Filter The output from the filter is the distortion and noise of the signal In the ac level mode the Notch Filter is bypassed After amplifying and low pass filtering the output from the Notch Filter is converted to dc by the Output RMS Average Detector and measured by the dc voltmeter When measuring distortion distortion level or SINAD the Notch Filter is automatically tuned to the frequency counted at the input to the filter Coarse tuning is via the Controller Fine tuning and balance are via circuitry internal to the Notch Filter In SINAD mode a front panel key allows you to lock the notch at a given input frequency so that the notch will not become untuned in the presence of noise The two Programmable Gain Amplifiers following the Notch Filter amplify the low level noise and distortion signals from the Notch Filter The overall gain of the two amplifiers is normally set to maintain a signal level of 0 3 to 3V at the MONTIOR output The 30 kHz and 80 kHz LP Filters are selected from the Keyboard With no low pass filtering the 3 dB bandwidth of the measurement system is approxi mately 750 kHz The filters are most often used to remove the high frequency noise components in low frequency SINAD and distortion measurements The output from the second Progr
60. the table of step 6 which corresponds to the 4 7 Performance Tests Model 8903E PERFORMANCE TESTS ac calibrator setting of 0 007 Vrms at the current frequency Divide the result by 100 The computed ratio should be within the limits indicated below For example if the reading in step b was 5 03 and the corresponding reading of step 6 ts 101 5 the computed result is 5 03 x 101 5 100 5 11 Synthesizer Displayed Limits of Computed Result Frequency Reading of Hz Step b 20 2 000 20 000 100 000 Low Level High Input AC Level Accuracy 10 Remove the adapters from the Distortion Analyzer s INPUT Connect the audio synthesizer s output directly to the Distortion Analyzer Set the Distortion Analyzer s INPUT switch to ground 11 Set the audio synthesizer to the frequency indicated in the table below For each setting perform the following procedure a Press RATIO if it is on Set the audio synthesizer to 7 mVrms as read on the Distortion Analyzer Press RATIO b Decrease the level of the audio synthesizer by exactly 26 dB Note the reading of the right display of the Distortion Analyzer c Multiply the reading on the right display by the entry in the table of step 3 which corresponds to the ac calibrator setting of 0 007 Vrms at the current frequency Divide the result by 100 Synthesizer Displayed Limits of Computed Result Frequency Reading of H2 Step b 95 100 000 20 000 2 000
61. to freeze the instrument in the presently selected settings for the input level ranges the post notch gain the decimal point position and the notch tuning To hold the presently selected settings for the functions above enter the HP IB program code 9 0SP To hold the present settings of the specified functions x 9 0SP Codec program codes For HP IB code refer to Example above As the program code is entered both displays will blank and the entered code will appear in the left display The displays will then show the normal readings for the currently selected measurement mode Using Special Function 9 is equivalent to entering the following special functions through the HP IB bus 1 N Input Level Range Except DC Level 2 N Input Level Range DC Level Only 3 N Post Notch Gain 4 N Hold Decimal Point Right Display Only 6 1 Hold Notch Tuning For Special Functions 1 through 4 N is set equal to the currently selected value that the instrument is using for that function These values can be read by using the Special Special Display refer to Special Functions Note that using the Hold Settings Special Function can cause inaccurate measurements under some circumstances Once settings have been held by the Hold Settings Special Function one or more of them can be reset to their automatic modes by issuing the 0 suffix code of the corresponding Special Function code As an example Hold Settings place
62. to remote Address the Distortion Analyzer to listen wrt 728 T1 completing the Remote message then send a Data message placing the Distortion Analyzer in Hold mode OUTPUT 728 T1 Send the Trigger message TRIGGER 728 trg 728 Address the Distortion Analyzer to talk and red 728 V store the data in variable V ENTER 728 V Display the value of V dsp V PRINT V Check that both the Distortion Analyzers REMOTE and ADDRESSED annunciators are on The controller s display should read 9009600000 00 HPL or 9009600000 BASIC Address the Distortion Analyzer to talk and red 728 V ENTER 728 V store the data in variable V Check that the controller s run indicator is still on indicating that it has not received data from the Distortion Analyzer Press the Distortion Analyzer s S Shift AVG RMS keys instrument clear The controller s run indicator should turn off 8903 3 12 REMOTE OPERATION HEWLETT PACKARD INTERFACE BUS The Distortion Analyzer can be operated through the Hewlett Packard Interface Bus HP IB Bus compat ibility programming and data formats are described in the following paragraphs Except for the LINE switch the low terminal ground FLOAT switch and the Controller Reset Service Spe cial Function all Distortion Analyzer operations in cluding service related functions are fully programmable via HP IB In addit
63. to the Distortion Analyzer s INPUT 3 Set the audio synthesizer frequency and level open circuit as indicated below For each setting the Distortion Analyzer s left display should agree with the frequency setting of the synthesizer to within the limits indicated If needed the synthesizer level can be checked with the Distortion Analyzer in its ac level mode Audio Synthesizer Frequency Hz Level mV MEASUREMENT Frequency Limits Hz Mode Minimum Actual Maximum 20 5 LEVEL 19 99 20 01 20 50 DISTN 19 99 20 01 99 300 DISTN 99 895 99 905 99 900 AC LEVEL 99 895 99 905 150 000 AC LEVEL 149 980 150 020 4 14 Model 8903 Performance Tests PERFORMANCE TESTS 4 11 AUDIO FILTERS PERFORMANCE TEST SPECIFICATION Characteristic Performance Limits Conditions AUDIO FILTERS 30 KHz Low Pass Filter 3 dB Cutoff Frequency 30 kHz 2 kHz 80 kHz Low Pass Filter 3 dB Cutoff Frequency 80 kHz 4 kHz 400 Hz High pass Filter Option 010 or 050 3 dB Cutoff Frequency 400 Hz i40 Hz 20 to 55 80 relative humidity 50 to 300 Hz 300 Hz to 3 kHz 800 Hz 3 to 3 5 kHz 3 5 to 5 kHz CCITT Weighting Filter Option 011 or 051 Deviation from Ideal Response 20 to 55 80 relative humidity 20 to 31 5 Hz 31 5 to 200 Hz 0 2 to 6 3 kHz 6 3 kHz 6 3 to 7 1 kHz 7 1 to 10 kHz 10 to 20 kHz 20 to 31 5 kHz
64. total clock counts by bit manipulation and proper weighting Line 40 Calculate E total cycle counts by bit manipulation and proper weighting Line 50 Calculate the frequency F total cycle count total clock count X 2 106 Note that the value is multiplied by 100 to round the integer part and then divide by 100 to round the answer to 2 digits to the right of the decimal Line 60 Displays the frequency count result Line 70 Terminates the program Using a HPL controller such as the Hewlett Packard Model 9825A Desktop Controller the computation is set up in seven steps as shown below 0 e O 7 wrt 728 RF fmt 2 4b red 728 r1 r2 r3 r4 shf r2 4 16 band r2 15 band r4 28 1024 260 r1 r5 band r4 15 16 255 3 2e6r6 r5 B dsp B end Explanation Line 0 Place the Distortion Analyzer in the Rapid Frequency Count mode Steps 1 2 Establish a format suitable for reading four binary bytes from the Distortion Line 3 Line 4 Line 5 Line 6 Line 7 Analyzer Take the readings and store the value in four variables The value stored is the decimal equivalent of the binary word Shift various bytes around and weight their value by the proper amount in accordance with the routine given to obtain the number of Distortion Analyzer clock counts Assign that value to variable r5 Position bits correctly and
65. 0 120 220 240 Vac 5 to 10 48 to 66 Hz single phase or 100 120 Vac 5 to 10 48 to 440 Hz single phase Power consumption is 100 VA maximum This is a Safety Class I product that is provided with a protective earth terminal An uninterruptible safety earth ground must be provided from the mains power source to the product input wiring termi nals power cord or supplied power cord set Whenever it is likely that the protec tion has been impaired the product must be made inoperative and be secured against any unintended operation If this instrument is to be energized via an external autotransformer make sure the autotransformer s common terminal is connected to the earthed pole of the power source 2 5 Line Voltage and Fuse Selection CAUTION BEFORE PLUGGING THIS INSTRU MENT into the Mains line voltage be sure the correct voltage and fuse have been selected Verify that the line voltage selection card and the fuse are matched to the power source Refer to Figure 2 1 Line Voltage and Fuse Selection Fuses may be ordered under HP part numbers 2110 0059 1 5A 250V time delay for 100 120 Vac opera tion and 2110 0018 0 75A 250V time delay for 220 240 Vac operation 2 6 Power Cables BEFORE CONNECTING THIS IN STRUMENT the protective earth termi nals of this instrument must be connected to the protective conductor of the Mains power cord The Mains plug shall only be inserted in
66. 0 110 00 010 111 00 011 000 00 011 001 00 011 010 00 011 011 00 011 100 00 011 101 00 011 110 00 011 111 00 100 000 00 100 001 00 100 010 00 100 011 00 100 100 00 100 101 00 100 110 00 100 111 00 101 000 00 101 001 00 101 010 00 101 011 00 101 100 00 101 101 00 101 110 00 101 111 00 110 000 00 110 001 00 110 010 00 110 011 00 110 100 00 110 101 00 110 110 00 110 111 00 111 000 00 111 001 00 111 010 00 111 011 00 111 100 00 111 101 00 111 110 00 111 111 Table 3 9 Commonly Used Code Conversions NONA Cn amp h md oO cO Nx S2 lt CH DOV Ozzr R amp I ommo OwO J ova C CY f od lt co lt OX 01 000 000 01 000 001 01 000 010 01 000 011 01 000 100 01 000 101 01 000 110 01 000 111 01 001 000 01 001 001 01 001 010 01 001 011 01 001 100 01 001 101 01 001 110 01 001 111 01 010 000 01 010 001 01 010 010 01 010 011 01 010 100 01 010 101 01 010 110 01010 111 01011 000 01 011 001 01 011010 01 011 011 01 011 100 01 011 101 01 011 110 01 011 111 01 100 000 01 100 001 01 100 010 01 100 011 01 100 100 01 100 101 01 100 110 01 100 111 01 101 000 01 101 001 01 101 010 01 101 011 01 101 100 01 101 101 01 101 110 01 101 111 01 110 000 01 110 001 01 110 010 01 110 011 01 110 100 01 110 101 01 110 110 01 110 111 01 1
67. 00 meters 50 000 feet 2 15 Packaging Original Packaging Containers and materials identi cal to those used in factory packaging are available through Hewlett Packard offices If the instrument is being returned to Hewlett Packard for servicing please fill out one of the blue tags located at the end of this manual Include on the tag the type of service required return address model number and full serial number and attach it to the instrument Mark the container FRAGILE to assure careful handling In any correspondence refer to the instrument by model number and full serial number Other Packaging The following general instructions should be used for re packaging with commercially available materials a Wrap the instrument in heavy paper or plastic If shipping to a Hewlett Packard office or service center complete one of the blue tags mentioned above and attach it to the instrument b Use a strong shipping container A doublewall carton made of 2 4 MPa 350 psi test material is adequate c Use enough shock absorbing material 75 to 100 mm layer 3 to 4 inches around all sides of instrument to provide a firm cushion and prevent movement in the container Protect the front panel with cardboard d Seal the shipping container securely e Mark the shipping container FRAGILE to as sure careful handling 2 5 Model 8903 Installation SHIELD CONNECT TO ATN EARTH SIGNAL GROUND
68. 000 2 000 20 104 102 102 102 4 26 8903 Performance Tests Table 4 1 Performance Test Record 2 of 10 Para No Test Description AC LEVEL ACCURACY PERFORMANCE TEST Contd cont d High Level High Input AC Level Accuracy Cont d Controller AC Calibrator Commands OUTPUT 728 Level Frequency SP Vrms Hz 3 0 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 4 27 Performance Tests Model 8903E Table 4 1 Performance Test Record 3 of 10 Test Description ________ LEVEL ACCURACY PERFORMANCE TEST Cont d High Level Low input AC Level Accuracy Controller AC Calibrator Commands OUTPUT 728 Vrms Hz 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 SP 4 28 Model 8903E Performance Tests Table 4 1 Perform
69. 000 20 000 2 000 20 1 195 0 0791 20 2 000 20 000 100 000 0 00791 100 000 20 000 2 000 20 High Level Low Input AC Level Accuracy 4 On the Distortion Analyzer set the INPUT switch to FLOAT 5 Connect the equipment as shown in Figure 4 1 Note how the cable connects to the Distortion Analyzer s input through the two adapters The adapters reverse the outer and inner conductor connections to the cable 8903E DISTORTION ANALYZER OF TERMINAL GROUND NDICATOR Figure 4 1 High Level Low Input AC Level Accuracy Test Setup Performance Tests Model 8903E PERFORMANCE TESTS nn EEE 6 Set the ac calibrator to the level indicated in the table Use the high voltage amplifier as needed Using the controller key in and execute the Special Function and ratio commands indicated in the table below Now set the ac calibrator to the frequency indicated in the table The right display of the Distortion Analyzer should read within the limits indicated NOTE If a controller is not being used follow the procedure of the Note in step 3 AC Calibrator Ratio Limits Controller Commands OUTPUT 728 1 6SP 30R1 Mmm _ 100 000 20 000 2 000 20 Level Vrms 0 20 2 000 20 000 100 000 1 7SP 15R1 100 000 20 000 2 000 20 1 85 1091 20 2 000 20 000 100 000 1 95 791 100 000 20 000 2 000
70. 1 Factory Selected Components Reference Service Range of Basis of Designator Values Selection A2C4 and A2C89 43 to 56 pF See Input Flatness Adjustment paragraph 5 8 A2C9 and A2C102 6 2 to 7 5 pF See Input Flatness Adjustment paragraph 5 8 A4R143 and A4R144 147 to infinity See Voltmeter Adjustment paragraph 5 13 or 14 Table 5 2 Post Repair Tests Adjustments and Checks Assembly Repaired Test Adjustment or Check A1 Keyboard and Dispiay Assembly Power Up Checks Service Special Functions Use 60 0 SPCL Key Scan and exercise all keys AC Level Accuracy Performance Test DC Leve Accuracy Performance Test Distortion and Noise Performance Test Audio Filters Performance Test Common Mode Rejection Ratio Performance Test Input Flatness Adjustment Common Mode Rejection Adjustment 400 Hz High Pass and Weighting Bandpass Filters Adjustment A3 Notch Filter Assembly Distortion and Noise Performance Test MENON Per Assem oren Fiter Tone and Saree ____ A4 Output Amplifier Voltmeter AC Level Accuracy Performance Test Assembly DC Level Accuracy Performance Test Distortion and Noise Performance Test Distortion and SINAD Accuracy Performance Test Voltmeter Adjustment Basic Functional Checks Frequency Accuracy and Sensitivity Performance Test Power Up Checks Basic Functional Checks Frequency Accuracy and Sensitivity Performance Test Internal Reference Frequency Adjustment Power Up Checks HP IB
71. 11 90 East and West Europe Saudi Arabia Egypt So Africa India unpolarized in many nations Mint Gray Mint Gray 125V 8120 1378 Straight NEMA5 15P 80 Black United States 8120 1398 90 80 Black Canada 8120 1754 Straight NEMA5 15P 36 Black Japan 100V or 8120 1378 Straight NEMA5 15P 80 Jade Gray 200V Mexico 8120 1521 90 80 Jade Gray Phillipines 8120 1676 Straight NEMA5 15P 36 Jade Gray Taiwan Straight SEV101 1 Gray Switzerland 1959 24507 Type 12 Straight NEMA6 15P United States Canada 79 Denmark 79 Gray Part number shown for plug is industry identifier for plug only Number shown for cable is HP Part Number for com cable including plug E Earth Ground L Line Neutral 250V 8120 2104 E 250V 8120 0698 220V 8120 1957 8120 2956 8120 1860 Straight DHCK107 90 Straight CEE22 VI Systems Cabinet use Figure 2 2 Power Cable and Mains Plug Part Numbers 2 3 Installation d Locate the HP IB address switch accessable through a hole near the center rear of the internal shield cover e Use a pencil to set the switches to the desired HP IB address and Talk Only TON or Listen Only LON condition The switch is illustrated in Figure 2 3 Facing the board the left hand switch marked with 5 is the most significant address bit A5 in Table 2 1 Setting a switch toward the pri
72. 11 000 01 111 001 01 111 010 01 111011 01 111 100 01 111 101 01 111 110 01 111 111 Model 8903E Model 8903B Description Procedure Example Program Code indications Measurement Technique Operation AC Level The Distortion Analyzer contains a wideband true rms or average responding voltmeter with high accuracy and sensitivity Pressing the AC LEVEL key causes the Distortion Analyzer to measure the differential ac voltage between the center and outer conductor of the INPUT connector or for Option 001 only the center conductors of the rear panel INPUT connectors Signals common to both high and low inputs are rejected See the following Warning and Caution To avoid the possibility of hazardous shock on standard instruments those without Option 001 do not apply more than 42V peak to the outer conductor of the BNC INPUT connector when the FLOAT switch is in the FLOAT position CAUTION Do not apply more than 300 Vrms either differential common mode a combination to the INPUT connector s To make an ac level measurement press the AC LEVEL key AC level results can be displayed in V mV dBm watts or as the ratio to an entered or measured value The Distortion Analyzer powers up displaying ac level in linear units mV or V To obtain a display in dBm that is dB relative to 1 milliwatt into a 600 ohm load equivalent to dBre 0 775V press the LOG LIN key T o return to linear simp
73. 2 Note how the cable connects to the Distortion Analyzer s input through the two adapters The adapters reverse the outer and inner conductor connections to the cable 4 9 Performance Tests Model 8903E PERFORMANCE TESTS 8903E DISTORTION ANALYZER DC STANDARD NOTE THE ORIENTATION OF THE GROUND TERMINAL GROUND INDICATOR Figure 4 2 Low Input DC Level Accuracy Test Setup 6 Set the dc standard to give the output voltage indicated below For each setting the right display on the Distortion Analyzer should read within the limits indicated Voltage Vdc 0 04 0 4 3 30 DC Voltage Limits Vdc 4 10 8903 Performance Tests PERFORMANCE TESTS 4 8 RESIDUAL DISTORTION AND NOISE PERFORMANCE TEST SPECIFICATION Characteristic Performance Limits Conditions DISTORTION AND SINAD Residual Noise and The higher of 80 dB 20 Hz to 20kHz Distortion or 15 uV 80 kHz bandwidth The higher of 70 dB 20 kHz to 50 kHz or 45 uV 500 kHz bandwidth The higher of 68 dB 50 kHz to 100 kHz or 45 uV 500 kHz bandwidth DESCRIPTION The output of a low distortion audio oscillator is connected to the Distortion Analyzer s input and the com bination of distortion and noise is measured at various frequencies and levels The test measures the distortion and noise of the oscilllator and analyzer simultaneously If either instrument is out of specification a known good osci
74. 20 1 10SP 4 581 20 2 000 20 000 100 000 1 115 3R1 100 000 20 000 2 000 20 1 128P 1 58 1 20 1 135 191 Model 8903 Performance Tests PERFORMANCE TESTS Controller Commands OUTPUT 728 1 14SP 0 7R1 AC Calibrator Ratio Limits 96 100 000 20 000 2 000 20 20 2 000 20 000 100 000 1 15SP 0 45R1 100 000 20 000 2 000 20 1 165 0 3R1 20 2 000 20 000 100 000 4 17 SP 0 15R1 100 000 20 000 2 000 20 1 185 0 1891 20 2 000 20 000 100 000 1 19 0 0791 100 000 20 000 2 000 20 0 00791 Low Level Low Input Level Accuracy 1 8 On the Distortion Analyzer press the LCL key and set RATIO Replace the ac calibrator with the audio synthesizer Leave the adapters as they are Set the audio sythesizer s level to approximately 7 mVrms as read on the Distortion Analyzer set the audio synthesizer to the frequency indicated in the table below For each setting perform the following procedure a Press RATIO if it is on Set the audio synthesizer to 7 mVrms as read on the Distortion Analyzer Press RATIO b Decrease the level of the audio synthesizer by exactly 26 dB Note the reading of the right display of the Distortion Analyzer c Multiply the reading on the right display by the entry in
75. 20 kHz to 100 kHz 20 Hz to 20 kHz 80 kHz BW 20 kHz to 50 kHz 500 kHz BW 50 kHz to 100 kHz 500 kHz BW Except on the 300 0V range 50 mV to 300V 20 Hz to 20 kHz 50 mV to 300V 20 kHz to 100 kHz 0 3 mV to 50mV 20 Hz to 100 kHz Except on the 300 0V range 600 mV to 300V Vin 600 mV Model 8903E General Information Table 1 1 Specifications 2 of 4 MEASUREMENT Cont d FREQUENCY Measurement Range 20 Hz to 150 kHz In ac level mode 20 Hz to 100 kHz In distortion and SINAD modes Resolution 5 digits Frequencies gt 100 Hz 0 01 Hz Frequencies lt 100 Hz Accuracy 0 004 1 digit Sensitivity 50 mV Distortion and SINAD modes only 5 0 mV In ac level mode only STANDARD AUDIO FILTERS 30 kHz Low pass Filter 3 dB Cutoff Frequency 30 2 kHz Rolioff 3rd order response 18 dB octave or 60 dB decade 80 kHz Low pass Filter 3 dB Cutoff Frequency 80 4 kHz Rolloff 3rd order response 18 dB octave or 60 dB decade PLUG IN AUDIO FILTERS 400 Hz Highpass Filter 3 dB Cutoff Frequency 400 40 Hz Rolloff 7th order response 42 dB octave or 140 dB decade CCITT Weighting Filter CCITT Recommendation P53 Deviation from Ideal 20 to 55 C 80 relative humidity Response At 800 Hz 300 Hz to 3 kHz 50 Hz to 3 5 kHz 3 5 kHz to 5 kHz CCIR Weighting Filter CCIR Recommendation 468 2 DIN 45405 Deviation from Ideal 20 to 55 C 8096 relative humidity Response At 6 3 kHz 6 3 kHz to 7 1 kHz 7 1 kHz to 10 kHz 200 Hz to
76. 3 Temperature 0 C to 55 Homidiy 4 obe EP bU Evae lt 95 relative Altitude lt 4570 meters 15 000 feet 2 11 Bench Operation The instrument cabinet has plastic feet and foldaway tilt stands for convenience in bench operation The plastic feet are shaped to ensure self aligning of the instruments when stacked The tilt stands raise the front of the instrument for easier viewing of the front panel 2 12 Rack Mounting The Distortion Analyzer is heavy for its size 11 8 kg 26 b Care must be exercised when lifting to avoid personal injury Use equipment slides when rack mounting CAUTION DO NOT BLOCK the ventilation holes in the bottom panel Since this instrument does not use a cooling fan it is important that good ventilation be provided Allow for 1 to 2 inches clearance around the bottom panel Rack mounting information is provided with the rack mounting kits If the kits were not ordered with the instrument as options they may be ordered through the nearest Hewlett Packard office Refer to para graph 1 13 Mechanical Options in Section 1 2 13 STORAGE AND SHIPMENT 2 14 Environment The instrument should be stored in a clean dry environment The following environmental limita tions apply to both storage and shipment Oe Installation Temperature 55 C to 75 C Humidity eee hie lt 95 relative Altitude 15 3
77. 5 Observe the right display of the Distortion Analyzer It should read 90 dB or less Readjust the two adjustments to minimize the reading on the display which must be 90 dB or less NOTE If the reading of step 5 cannot be brought within limit it may be that the source has excessive distortion 8903 Adjustments ADJUSTMENTS 5 13 VOLTMETER ADJUSTMENT USING AN HP IB CONTROLLER Reference Service Sheets 6 and 7 Description The Distortion Analyzer is set to measure the ac level from an audio oscillator The internal ac to dc converter as yet uncalibrated produces a dc voltage that is read by the internal dc voltmeter and monitored by an external dc voltmeter The sensitivity of the internal dc voltmeter is adjusted so that the amplitude display of the Distortion Analyzer agrees with the level measured by the external dc voltmeter The ac level from the audio oscillator is then monitored by an external ac voltmeter The ac to dc converter is adjusted so that the amplitude display of the Distortion Analyzer agrees with the level measured by the external ac voltmeter at two different levels Since there are two ac to dc converters one true rms responding and one average responding two separate adjustments are made NOTE If an HP IB controller is not available use the next adjustment procedure Voltmeter Adjustment Not Requiring an HP IB Controller Equipment Audio
78. 5V or 0 596 high Thus the measurement result would be 9 95 distortion instead of the true 10 Actually you can see that the distortion must really be excessive to affect the measurement significantly Now consider the case where other types of impurities are significant Suppose the actual total harmonic distortion is 196 but that there 1s an additional hum component that has a level that is 1 of the funda mental level T he distortion measured by a distortion analyzer wil be 1 4 that is 40 or 3 dB high How then can you be sure that the result is a valid measurement of distortion One way is to observe the MONITOR output with an oscilloscope If the waveform is clean and harmonically related to the fundamental the measurement is actual total har monic distortion If it is not selectable filters are provided to remove unwanted signals Use the op tional 400 Hz High Pass Filter to remove line hum Use the 30 kHz or 80 kHz Low Pass Filter to remove out of band noise However select only filters that do not affect the fundamental and the harmonics of interest Sometimes it is desired to include hum and noise as part of the distortion measurement For 1 10 eS eS eee Model 8903E this reason the measurement is often referred to as a THD N total harmonic distortion plus noise measurement 1 36 SINAD For most practical purposes the SINAD measurement as made by the Distortion Analyzer is equal to th
79. 6 3 kHz 31 5 Hz to 200 Hz 10 kHz to 20 kHz 20 kHz to 31 5 kHz General Information PLUG IN AUDIO FILTERS Cont d C MESSAGE Weighting Filter Deviation from Ideal Response CCIR ARM Weighting Filter Deviation from Ideal Response A Weight Filter Deviation from Ideal Response TEMPERATURE Operating Storage INPUT TYPE MAXIMUM INPUT INPUT IMPEDANCE Resistance Shunt Capacitance COMMON MODE REJECTION RATIO REMOTE OPERATION 1 14 8903 Table 1 1 Specifications 3 of 4 MEASUREMENT Cont d 0 1 dB 1 0 dB 0 1 dB 0 2 dB 0 4 dB 0 5 dB 1 0 dB 2 0 dB 0 1 dB 0 5 dB 1 0 dB 0 to 55 C 55 to 75 C Balanced 42V Peak 42V Peak 100 1 101 1 lt 300 gt 60 dB gt 45 dB gt 30 dB HP IB STD 488 1978 Compatibility Code SH1 AH1 T5 L3 LEO SR1 RL1 PPO DC1 DT1 CO E1 Per BSTM 41004 20 to 55 C 80 relative humidity At 1 kHz 60 Hz to 5 kHz CCIR Recommendation 486 2 averaging responding meter Dolby Labs bulletin No 19 4 20 to 55 C 80 relative humidity At 6 3 kHz 6 3 kHz to 7 1 kHz 7 1 kHz to 10 kHz 200 Hz to 6 3 kHz 31 5 Hz to 200 Hz 10 kHz to 20 kHz 20 kHz to 31 5 kHz IEC Recomendation 179 and ANSI 51 4 type 1 sound level meter 20 to 55 C 80 relative humidity At 1 kHz 20 Hz to 10 kHz 10 kHz to 20 kHz Full differential Differentially applied or between high input an
80. AD ratios less than 25 dB a Special Function can be used to round the digital display to the nearest 0 5 dB to reduce digit flicker For accurate noise ratio measurements the Distortion Analyzer uses true rms detection for SINAD Most older instruments employ average detection which reads low for noise The discrepancy can be 1 5 dB or greater and varies with the ratio being measured For correlating results with past test data the Distortion Analyzer s detector can be switched via a front panel key to an average responding configuration For transceivers the Distortion Analyzer has an op tional internal plug in seven pole 400 Hz high pass filter for rejecting squelch tones Rejection of squelch General Information tones up to 250 Hz is greater than 40 dB Therefore audio distortion measurements to 196 residual distortion can be made without disabling the trans mitter squelch tones Under remote control the Distortion Analyzer can count burst tone sequences Typically the maximum count rate is 8 ms reading 1 10 Systems The Distortion Analyzer features capabilities for gen eral systems applications The distortion measure ments are fully automatic programmable and fast The typical time to tune and return the first distortion measurement is 1 5 seconds with a measurement rate of 2 readings second thereafter The residual distortion of the analyzer is typically 0 003 90 dB between 20 Hz and 20 kHz Often syst
81. ATIO key can be used to compare the measured results to a predetermined ratio reference refer to RATIO and LOG LIN To make a distortion level measurement you must use the HP IB Distortion Level program code 53 The filters are used to limit the bandwidth The Distortion Analyzer powers up with the LOW PASS 80 kHz filter activated measure distortion level on an external source signal in a 30 kHz bandwidth um 5311 program codes Measurement p Filter S3 1s the HP IB code for distortion level When distortion level is selected the frequency and amplitude of the input signal are displayed and the appropriate annunciators and DISTN key light will light see Description above In the distortion level measurement mode the controller automatically sets the input attenua tion and the gain settings of various amplifiers This control ensures that the signal amplitude is within the proper range for the output detector The notch filter removes the fundamental from the input signal The notch filter automatically tunes to the component whose frequency is measured by the counter usually the fundamental of the input signal The output detector converts the residual noise distortion to dc The dc voltmeter measures the signal and the controller corrects for the programmed gain and attenuation The results are then displayed in the appropriate units The frequency of the input is also measured and displayed Distortion Level Me
82. Data values never exceed 4 000 000 000 Operation lt p Data Output Format DDDDDE NNCRLFE Line Feed Carriage Return Signed Mantissa Indicates Exponent Follows Exponent Sign Exponent Magnitude NOTE For the only exception to the above format refer to Rapid Frequency Count in the Detailed Operating Instructions When an error is output to the bus it follows the same twelve byte format described above except most of the numeric digits have predetermined values as shown below Error outputs always exceed 9 000 000 000 The two digit error code is represented by the last two digits of the five digit mantissa The error code can be derived from the string by subtract ing 9 X 103 then dividing the results by 100 000 Error Output Format 900DDE 05CRLFE Line Feed Error Code Carriage Return 3 20 Receiving the Clear Message The Distortion Analyzer responds to the Clear message by assuming the settings detailed in Table 3 5 The Distortion Analyzer responds equally to the Selected Device Clear SDC bus command when addressed to listen and the Device Clear DCL bus command whether addressed or not The Clear message clears any pending Require Service message and resets the Service Request Condition Special Function 22 such that the Require Service message will be issued on HP IB code errors only Special Function 22 2 Table 3 5 Response to a Clear Message Sm Measurement Low Pass
83. E dB Operation Filters cont d High Pass Bandpass Low Pass re aie ee eee E NEN aaa ee Weighting tH A poe ee E A Weighting Filter C Message Weighting Filter ae NE NE l l et D tT tt dL Ll 1 kHz 100 kHz FREQUENCY Hz A Weighting and C Message Weighting Filter Plot 3 53 Model 8903E Filters cont d High Pass Bandpass Low Pass Related AC Level Sections Distortion Distortion Level SINAD 3 54 Model 8903E Description Procedure Comments Operation Float To minimize measurement errors caused by ground loops the analyzer input can be floated Floating the input improves rejection of low frequency and common mode signals for example line related hum and noise The front panel FLOAT switch determines whether the input is floating or single ended When in the float mode the analyzer input is fully balanced To avoid the possibility of hazardous shock on standard instruments those without Option 001 do not apply more than 42V peak to the outer conductor of the BNC INPUT connector when the FLOAT switch ts in the FLOAT position Do not apply more than 300 Vrms either differential common mode or a combination to the INPUT connector s To float the analyzer input set the FLOAT switch to the FLOAT position In
84. Errata Title amp Document Type 8903E Operation amp Calibration Manual Manual Part Number 98903 90053 Revision Date 1985 HP References in this Manual This manual may contain references to HP or Hewlett Packard Please note that Hewlett Packard s former test and measurement semiconductor products and chemical analysis businesses are now part of Agilent Technologies We have made no changes to this manual copy The HP XXXX referred to in this document is now the Agilent XX XX For example model number HP8648A is now model number Agilent 8648A About this Manual We ve added this manual to the Agilent website in an effort to help you support your product This manual provides the best information we could find It may be incomplete or contain dated information and the scan quality may not be ideal If we find a better copy in the future we will add it to the Agilent website Support for Your Product Agilent no longer sells or supports this product You will find any other available product information on the Agilent Test amp Measurement website www tm agilent com Search for the model number of this product and the resulting product page will guide you to any available information Our service centers may be able to perform calibration if no repair parts are needed but no other support from Agilent is available 225 Agilent Technologies e PM e e 9 70 HP 8903E Distortion Analyzer Ope
85. FORMANCE TEST SPECIFICATION Characteristic Performance Limits Conditions AC LEVEL Accuracy 50 mV to 300V 20 Hz to 20 kHz 50 mV to 300V 20 kHz to 100 kHz 0 3 mV to 50 mV 20 Hz to 100 kHz DESCRIPTION For each ac range ac level accuracy is determined by measuring the output of an ac calibrator In addition for the lowest range the output of an audio synthesizer is set to the lowest level of the just completed calibration This level is established as a ratio reference then the signal is attenuated by a precise amount The procedure is run with the outer conductor of the input connector grounded then with the inner conductor grounded and the signal applied to the ungrounded outer conductor A controller with HP IB is recommended for this test since it provides the most convenient method for setting level ranges However an alternate method not requiring a controller is also mentioned in the procedure Voltages up to 300 Vrms will be applied to the Distortion Analyzer s input connector EQUIPMENT AC Calibrator HP 754A and HP 746A Datron 4200 ee EEE eee E or Fluke 5200A and Fluke 5215 Audio Synthesizer RIPE RAE Rau ERES HP 3336C Controller with HP IB HP 85B Opt 007 Dual Banana to BNC Adapter 10110B Dual Banana to BNC Adapter HP 1251 2277 PROCEDURE NOTE The Distortion Analyzer s HP IB address is assumed to
86. Functional Checks Power Up Checks A2 Input Amplifier Assembly A7 Latch Assembly A8 Controller Counter Assembly A9 Remote Interface Assembly A10 Remote Interface Connector Assembly A11 Series Regulator Socket Assembly A12 Connector Filter Assembly A13 Power Supply and Mother Board Assembly A14 Line Power Module These paragraphs are found in the HP 8903B Service Manual Basic Functional Checks Power Up Checks 5 2 Model 8903 Adjustments ADJUSTMENTS 5 7 INTERNAL REFERENCE FREQUENCY ADJUSTMENT Reference Service Sheet 15 Description An oscilloscope triggered by an external reference is used to monitor the internal reference frequency while it is adjusted Equipment Frequency Standard House Standard OSCINOSCODG Card wise HP 1740A 15 EXTERNAL TRIGGER VERTICAL INPUT OUTPUT FREQUENCY STANDARD 8903E DISTORTION ANALYZER Figure 5 1 Internal Reference Frequency Adjustment Test Setup Procedure Allow the equipment to warm up for 15 minutes 2 Connect the equipment as shown in Figure 5 1 The figure shows the setup for house standard frequencies of 2 MHz or lower If the frequency of the frequency standard is 5 or 10 MHz reverse the vertical input and external trigger connections on th
87. IB codes for re entering ratio or for reading the reference are given above The HP IB codes for the RATIO and LOG LIN keys are given below LOG LG LIN LN RATIO Off RO RATIO On R1 When the instrument is displaying a ratio measurement the RATIO key lights The status of the LOG LIN key can be determined by observing the the current measurement mode the measurement unit lights and the table above The ratio mode can also be used to view an extra digit of resolution when the right display is only showing three digits Depending upon the current value displayed entering either 100R1 or 1R1 will cause an unscaled right display readout that is the numbers are correct but the decimal point may not be in the correct position However an extra digit of resolution is displayed for example if 1 58 was originally displayed the new display might indicate 1 576 Note that the units annunciator will change to and should be interpreted properly Ratio cannot be used with a frequency measurement Also if a negative reference is entered the ratio indication will be displayed in absolute unsigned value The LOG function cannot be used with a reference that is zero or negative If the reference is zero Error 20 entered value out of range is displayed If the reference is negative Error 11 calculated value out of range is displayed AC Level DC Level Distortion Distortion Level Error Message Summary SINAD Special F
88. Model 8903E x OPERATOR S CHECKS Send the serial poll enable bus command wti 0 7 wti 6 24 SENDBUS 728 1 24 SPE through the interface to place the Distortion Analyzer in mode Send Special Function 61 3 wrt 728 61 35 OUTPUT 728 61 3SP OPERATOR S On the Distortion Analyzer the right display should show 1 0 This indicates the Distortion RESPONSE Analyzer is in serial poll mode indicated by the 1 Send the Abort message removing the cli 7 ABORTIO 7 Distortion Analyzer from serial poll mode OPERATOR S Check that the Distortion Analyzer s right display shows 0 0 This indicates the Distortion RESPONSE Analyzer properly left serial poll mode upon receiving the Abort message Status Byte Message NOTE This check determines whether or not the Distortion Analyzer sends the Status Byte message in both the local and remote modes This check assumes that the Distortion Analyzer is able to handshake recognize its own address and make the remote local changes Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON es _ Place the Distortion Analyzer serial poll rds 728 V STATUS 728 V mode and address it to talk causing it to send the Status Byte message Display the value of V dsp V PRINT V OPERATOR S Check that Distortion Analyzers REMOTE annunciator is off Depending upon the RESPONSE vintage
89. NTER LEFT DISPLAY FREQUENCY LI CC C INTERNAL HP BP OUTPUT INPUT FILTERS RMS AVE VOLTMETER TT 7 LOW PASS RIGHT DISPLAY ATTENUATOR FILTERS grids AMPLITUDE EH rE 48889 PROGRAMABLE PROGRAMABLE Lim INPUT AMPLIFIER GAIN AMPLIFIER GAIN AMPLIFIER MONITOR AC Level Measurement Block Diagram The Distortion Analyzer powers up in the ac level measurement mode with the 80 kHz low pass filter activated The 80 kHz low pass filter reduces the measurement bandwidth from 750 kHz to 80 kHz Two ac level detectors are available true rms and average responding but rms calibrated See the section Detector Selection for details Common Mode Detector Selection Display Level in Watts Filters Monitor RATIO and LOG LIN Special Functions Model 8903E Operation Automatic Operation Description The Automatic Operation code sets the instrument functions to automatic that is each function is allowed to automatically range to the appropriate setting It also cancels all of the special functions Procedure To set the Distortion Analyzer to automatic operation you must use HP IB Example To set the Distortion Analyzer to automatic operation x T program codes Function Program Code AU is the HP IB code for Automatic Operation Indications When the HP IB program code is entered the left and right displays blank the right display shows four dashes then both displays show the current measurem
90. Pass Setting Hz Filter Minimum 400 Hz HP 30 kHz LP 80 kHz LP Option 010 or 050 4 Key in and execute the following command on the controller OUTPUT 728 48 1SP to enable up ranging of the output gain Press LCL Set the audio synthesizer s frequency as indicated below in the table appropriate for the installed weighting filter For each setting perform the following procedure a Set all filters off Set RATIO off b Set RATIO on Select the appropriate weighting filter The displayed ratio should be within the limits indicated Table for CCITT Weighting Filter Option O11 or 051 SOURCE Ratio Limits dB Frequency Hz 4 17 Performance Tests Model 8903 PERFORMANCE TESTS Table for CCIR Weighting Filter Option 012 or 052 SOURCE Ratio Limits dB Frequency 4 18 Model 8903 PERFORMANCE TESTS Table for C Message Weighting Filter Option 013 or 053 SOURCE Frequency Hz Performance Tests Performance Tests Model 8903E PERFORMANCE TESTS Table for CCIR ARM Weighting Filter Option 014 or 054 SOURCE Frequency 4 20 8903 Performance Tests PERFORMANCE TESTS Table for A Weighting Filter Option 015 or 055 SOURCE Ratio Limits dB Frequency 4 21 Performance Tests Model 8903E PERFORMANCE TESTS 4 12 INPUT IMPEDANCE PERFORMANCE TEST SPECIFICATION Characteristic Performance Limits Conditions
91. RS PERFORMANCE TEST Cont d CCIR Weighting Filter Option 012 or 052 Cont d 4 000 5 000 6 300 7 100 8 000 9 000 10 000 12 500 14 000 16 000 20 000 31 500 110 0 dB 11 2 dB 12 1 dB 11 8 dB 11 0 dB 19 7 7 7 dB 1 0 dB 6 3 dB 12 7 dB 23 2 dB 44 7 dB 11 0 dB 12 2 dB 12 3 dB 12 2 dB 11 8 dB 10 5 dB 8 5 dB 1 0 dB 4 3 dB 10 7 dB 21 2 dB 40 7 dB C Message Weighting Filter Option 013 or 053 60 100 200 300 400 500 600 700 800 900 1 000 1 200 1 300 1 500 1 800 2 000 2 500 2 800 3 000 3 300 3 500 4 000 4 500 5 000 CCIR ARM Weighting Filter Option 014 or 054 31 5 63 100 200 400 800 1 000 4 33 Performance Tests Model 8903E Table 4 1 Performance Test Record 9 of 10 SOURCE Frequency Hz Cont d CCIR ARM Weighting Filter Option 014 or 054 Cont d 2 000 3 150 4 000 5 000 6 300 7 100 8 000 9 000 10 000 12 500 14 000 16 000 20 000 31 500 A Weighting Filter Option 015 or 055 20 25 31 5 40 50 63 80 4 34 Model 8903 Table 4 1 Performance Test Record 10 of 10 b3 Test Description INPUT TEST High Input Low Input 49 00 MODE REJECTION RATIO TEST Controller Commands Oscillator F OUTPUT 728 scillator Frequency SP Hz Performance Tests 4 35 Model 8903E Adjustments Section 5 ADJUSTMENTS 5 1 INTRODUC
92. S Indicates instrument damage can occur if indicated operating limits are exceeded Indicates hazardous voltages L Indicates earth ground terminal WARNING A WARNING note denotes a hazard It calls attention to a procedure practice or the like which if not correctly performed or adhered to could result in personal injury Do not proceed beyond a WARNING sign until the indicated conditions are fully understood and met CAUTION A CAUTION note denotes a hazard It calls attention to an operation procedure practice or the like which if not correctly performed or adhered to could result in damage to or destruction of part or all of the product Do not proceed beyond an CAUTION note until the indicated conditions are fully understood and met 2 Chapter 1 es o Regulatory Information Updated March 1999 Safety Considerations for this Instrument WARNING This product is a Safety Class I instrument provided with a protective earthing ground incorporated in the power cord The mains plug shall only be inserted in a socket outlet provided with a protective earth contact Any interruption of the protective conductor inside or outside of the product is likely to make the product dangerous Intentional interruption is prohibited Whenever it is likely that the protection has been impaired the instrument must be made inoperative and be secured against any unintended operation If this instrument is to be energized via
93. STRUCTIONS 3 33 222p et 3 33 Automatic Operation 3 35 Common Mode 3 36 3 39 Default Conditions and Power up Sequence 3 40 Detector Selection 3 41 Display Level in Watts 3 42 Distortion visse WS RE Sees 3 43 Distortion Level 3 45 Error 3 47 Error Message Summary 3 48 Filters 3 51 Float 3 55 Hold Decimal Point 3 57 Hold Settings 3 58 HP IB Address 3 59 Input Level Range DC Level 3 61 Input Level Range Except DC Level 3 62 MONOT ess dex Aree iate eda 3 64 Notch Tune 3 67 Post Notch Detector Filtering Except SINAD 3 68 Post Notch Gain 3 69 Rapid Frequency Count 3 70 RATIO and LOG LIN 3 73 Read Display to HP IB 3 75 Service Request Condition 3 76 SINAD os dcr 3 78 Special Functions 3 80 Time Between Measurements 3 86 Section 4 PERFORMANCE TESTS Introduction e ed te EE SS E head 4 1 Equipment Required 4 1 Test Record eoo der ou en xtv e xui dps oe 4 1 Calibration Cycle
94. Shift NOTCH TUNE The left display should read 11214 NOTE Do not press any additional keys until step 8 This display must be present through step in order to prevent instrument ranging Set the audio oscillator to 3 Vrms at 1 kHz Adjust A4R91 RMS SCALE for a reading on voltmeter B that is the same as the reading on voltmeter A within 1 mV See Service Sheet 6 Set the audio oscillator amplitude to 150 mV Adjust A4R85 RMS OFFSET for a reading on voltmeter B that is the same as the reading on voltmeter A within 0 5 mV See Service Sheet 6 If A4R85 does not have sufficient range add or alter A4R143 or A4R144 as follows a Unsolder A4R143 or 4 144 if present b With a dc voltmeter measure the voltage at the junction of A4R72 and A4C46 c If the voltage ignoring polarity is greater than 2 mV compute R 1500 V where is the voltage measured in volts d Select a resistor which has a standard value resistance nearest R If the measured voltage is negative solder the new resistor in the location for A4R143 if positive replace A4R144 e After a five minute warm up measure the voltage again which should be between 2 and 2 mV dc f Repeat the adjustment of A4R85 Set the audio oscillator amplitude to 3V Repeat steps 5 through 7 until the readings for voltmeter A and voltmeter B agree within the limits stated for both 3V and 150 mV On the Distortion Analyzer select the averaging
95. TERNAL FUSES BNC TO BANANA PLUG ADAPTER OPTION 909 OPTION 907 RACK FLANGE AND FRONT FRONT HANDLE KIT HANDLE COMBINATION KIT OPTION 908 RACK FLANGE KIT NOTE Refer to ACCESSORIES SUPPLIED for more details Figure 1 2 HP Model 8903E Accessories Supplied and Options 907 908 and 909 General Information 1 21 Rear to Front Panel Connectors Retrofit Kit This kit contains all the necessary components and full instructions for converting instruments with rear panel connections for INPUT and MONITOR to front panel connections Order HP part number 08903 60178 After installation and calibration performance will be identical to the standard HP 8903E 1 22 MECHANICAL EQUIPMENT AVAILABLE 1 23 Chassis Slide Mount Kit This kit is extremely useful when the Distortion Analyzer is rack mounted Access to internal circuits and components or the is possible without removing the instrument from the rack Order HP part number 1494 0060 for 431 8 mm 17 in fixed slides and part number 1494 0061 for the correct adapters for non HP rack enclosures 1 24 Chassis Tilt Slide Mount Kit This kit is the same as the Chassis Slide Mount Kit above except it also allows the tilting of the instru ment up or down 90 Order HP part number 1494 0062 for 431 8 mm 17 in tilting slides and number 1494 0061 for the correct adapters for non HP rack enclosures DIFFERENTIAL TO SINGLE PROGRAMMABLE
96. TION This section contains adjustments and checks that assure peak performance of the Distortion Analyzer The instrument should be readjusted after repair or failure to pass a performance test Allow a 30 minute warm up prior to performing the adjustments Removing the instrument top cover and the internal shield cover ts the only disassembly required for all adjustments To determine which performance tests and adjustments to perform after a repair refer to paragraph 5 5 Post Repair Tests Adjustments and Checks 5 2 SAFETY CONSIDERATIONS This section contains information cautions and warnings which must be followed for your protection and to avoid damage to the equipment Adjustments described in this section are performed with power Supplied to the instrument and with protective covers removed Maintenance should be performed only by service trained personnel who are aware of the hazard involved for example fire and electrical shock Where maintenance can be performed without power applied the power should be removed 5 3 EQUIPMENT REQUIRED Most adjustment procedures contain a list of required test equipment The test equipment is also identified by callouts in the test setup diagrams where included If substitutions must be made for the specified test equipment refer to Table 1 3 in Section 1 of this manual for the minimum specifications It is important that the test equipment meet the critical specifications listed in
97. The measurement result data available to the bus are constantly being updated as rapidly as the Distortion Analyzer can make measurements Device Clear message or entry into remote from local sets the Distortion Analyzer to the Free Run mode Hold T1 This mode is used to set up triggered measurements initiated by program codes T2 or the Trigger message or the Clear Key Function ex plained below In Hold mode internal settings can be altered by the instrument itself or by the user via the bus Thus the signal at the MONITOR output can change However the instrument is inhibited from outputting any data to the front panel key lights and display or to the HP IB except as follows The instrument will issue the Require Service message or if an HP IB code error occurs The instrument will issue the Status Byte message if serial polled A serial poll however will trigger a new measurement update displays and return the instrument to Hold Upon leaving Hold the front panel indications are updated as the new measurement cycle begins The Status Byte will be affected and the Require Service message issued by the events that occur during the new measurement cycle The Distortion Analyzer leaves Hold when it receives either the Free Run Trigger Immediate Trigger with Settling codes or the Trigger Message when the S Shift AVG RMS keys the Clear Key Function are pressed if not in Local Lockout or when it returns to lo
98. Weighting Filter Option 012 or 052 Oscillator Frequency Hz Ratio Limits dB Operation Model 8903E OPERATOR S CHECKS Table for C Message Weighting Filter Option 013 or 053 Oscillator Frequency Hz Ratio Limits dB 44 0 to 9 0 to 0 2 to 4 0 to 30 0 to Table for CCIR ARM Weighting Filter Option 014 or 054 Oscillator Frequency Hz Ratio Limits dB Table for A Weighting Filter Option 015 or 055 Oscillator Frequency Hz Ratio Limits dB Distortion Check 15 Set all filters on the Distortion Analyzer off Press the LOW PASS 80 kHz key Press the DISTN key The DISTN key light should light 16 Set the audio oscillator frequency to 1 kHz The right display should show 0 01 or less SINAD Check 17 Press the S Shift SINAD keys The SINAD key light should light The right display should show 80 dB or more 18 Press the Notch Tune key The NOTCH TUNE KEY light should light 19 Set the audio oscillator frequency to 890 Hz The right display should show between 12 and 19 dB DC Level Check 20 Press the S Shift and DC LEVEL keys The DC Level light should light The right display should show between 10 and 10 mV With an ac voltage applied to the input the reading will not be steady rp ER POV 3 10 c Model 8903E Operation x OPERATOR S CHECKS 3 11 HP IB Functional Checks DESCRIPTION The following ten procedure
99. a Data message enabling a Require Service message to be sent upon Instrument Error Make the controller wait 2 seconds to allow wait 2000 WAIT 2000 time for the Distortion Analyzer to send the Require Service message This step is not necessary if sufficient time is allowed Read the binary status of the controller s rds 7 V STATUS 7 V HP IB interface and store the data in varia ble V in this step 7 is the interface s select code Display the value of the SRQ bit in in this dsp SRQ bit PRINT SRQ BIT V 7 step 7 is the SRQ bit numbered from 0 7 V OPERATOR S Check that the SRQ value is 1 indicating the Distortion Analyzer issued the Require RESPONSE Service message Trigger Message and Clear Key Triggering NOTE This check determines whether or not the Distortion Analyzer responds to the Trigger message and whether the CLEAR key serves as a manual trigger in remote This check assumes that the Distortion Analyzer is able to handshake recognize its own address make the remote local changes and send and receive Data messages Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON then when the power up sequence is complete press the DISTN key 3 17 Operation x Model 8903E OPERATOR S CHECKS OPERATOR S RESPONSE OPERATOR S RESPONSE HPL BASIC Send the first part of the Remote message REMOTE 7 enabling the Distortion Analyzer
100. a socket outlet provided with a protective earth contact The protective action must not be negated by the use of an extension cord power cable without a protective conductor grounding 2 1 Installation This instrument is equipped with a three wire power cable When connected to an appropriate ac power receptacle this cable grounds the instrument cabinet The type of power cable plug shipped with each instrument depends on the country of destination Refer to Figure 2 2 for the part numbers of the power cables available 2 7 HP IB Address Selection 4E This task should be performed only by serv ice trained persons who are aware of the potential shock hazard of working on an instrument with protective covers removed To avoid hazardous electrical shock the line Mains power cable should be discon nected before attempting to change the HP IB address In the Distortion Analyzer the HP IB talk and listen addresses are selectable by an internal switch The Model 8903E following procedure explains how the switches are to be set Refer to Table 2 1 for a listing of the talk and listen addresses The address is factory set for a Talk address of and a listen address of lt In binary this is 11100 in decimal it is 28 To change the HP IB address the top cover of the Distortion Analyzer must be removed a Disconnect the line Mains power cable b Remove any HP IB cables or connectors from the HP IB
101. ad resistance in ohms must be an integer for example a resistance of 5 80 cannot be entered The decimal point has already been used when entering the Special Function An attempt to enter a second decimal point is ignored Remember that the instrument assumes that the input voltage is being developed across the specified external load resistance If an incorrect resistance is entered the readout in watts is shown for the resistance entered Zeros immediately following the decimal point are optional For example when setting the load resistance to 1 ohm 19 1 is equivalent to 19 01 and 19 001 However 19 1 is not equivalent to 19 10 or 19 100 Note that 19 19 0 and 19 8 are equivalent that is they both specify an 80 load resistance The displayed power level is accurate regardless of distortion unless the Distortion Analyzer s audio detector is set to average responding Neither the RATIO nor the LOG function can be used with this Special Function AC level Detector Selection Model 8903 Description Procedure Example Program Code Indications Measurement Technique Operation Distortion The Distortion Analyzer measures distortion by first determining the following value _ noise distortion signal noise distortion It then converts D into the appropriate measurement units as follows units D X 100 dB units 20log D The RATIO key can be used to compare the measured results to a predetermined
102. al dc voltmeter The sensitivity of the internal dc voltmeter is adjusted so that the amplitude display of the Distortion Analyzer agrees with the level measured by the external dc voltmeter NOTE If an HP IB controller is available this adjustment can be simplified using the previous adjustment procedure Voltmeter Adjustment Using an HP IB Controller Equipment Audio HP 8903B or HP 339A Digital Voltmeter A e u 3468 Digital Voltmeter arses HP 3455A NOTE Voltmeter A is optional If one voltmeter is used connect it as required between the points indicated in the procedure and Figure 5 7 Set it to read dc volts when connected to A4TPI and ac volts when connected to the tee at the Distortion Analyzer s INPUT Record the readings for comparison in subsequent steps Procedure 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground 2 Connect the equipment as shown in Figure 5 7 Connect voltmeter B to A4TP1 DC OUT and set it to measure dc volts Set voltmeter A to measure ac volts Set the audio oscillator to 2 5 Vrms at 1 kHz AATP 1 DC OUT p E VOLTMETER A 8903E DISTORTION ANALYZER AUDIO OUTPUT DIGITAL OSCILLATOR E VOLTMETER B Figure 5 7 Voltmeter Adjustment Test Setup 5 16 8903 Adjustments ADJUSTMENTS 10 11 Press S Shift NOTCH TUNE
103. ammable Gain Amplifier drives the front panel MONITOR output connector The frequency of this signal is also measured by the Counter in the ac level mode because of the increased sensitivity at this point The Output Detector is read by the dc voltmeter in the ac level SINAD the denominator distortion the numerator and distortion level modes It is also used to set the gain of the two Programmable Gain Amplifiers Both the input and output detectors can be configured via front panel keys to respond to the absolute average of the signal instead of the true rms value The Voltage to Time Converter converts the dc inputs into a time interval which is measured by the Counter 1 28 Counter The Counter is a reciprocal counter To measure frequency it counts the period of one or more cycles of the signal at its input then the Controller divides the number of periods by the accumulated count The reference for the Counter is the 2 MHz Time Base which also is the clock for the Controller The Counter has three inputs and two modes of operation 1 7 General Information Voltage Measurement The time interval from the Voltage to Time Converter is counted The accumu lated count is proportional to the dc voltage For direct measurements ac level dc level and distortion level the count is processed directly by the Controller and displayed on the right display For ratio measure ments SINAD and distortion the counts of t
104. an auto transformer for voltage reduction make sure the common terminal is connected to the earth terminal of the power source If this product is not used as specified the protection provided by the equipment could be impaired This product must be used in a normal condition in which all means for protection are intact only No operator serviceable parts in this product Refer servicing to qualified personnel To prevent electrical shock do not remove covers Servicing instructions are for use by qualified personnel only To avoid electrical shock do not perform any servicing unless you are qualified to do so The opening of covers or removal of parts is likely to expose dangerous voltages Disconnect the product from all voltage sources while it is being opened The power cord is connected to internal capacitors that my remain live for 5 seconds after disconnecting the plug from its power supply For Continued protection against fire hazard replace the line fuse s only with 250 V fuse s or the same current rating and type for example normal blow or time delay Do not use repaired fuses or short circuited fuseholders Always use the three prong ac power cord supplied with this product Failure to ensure adequate earth grounding by not using this cord may cause product damage This product is designed for use in Installation Category and Pollution Degree 2 per IEC 1010 and IEC 664 respectively FOR INDOOR USE ONLY
105. ance 49 90 50 40 Display with 500 Impedance 49 00 51 00 4 On the Distortion Analyzer set the INPUT switch to FLOAT 5 Connect the equipment as shown in Figure 4 4 Note how the cable connects to the Distortion Analyzer s input through the two adapters The adapters reverse the outer and inner conductor connections to the cable 4 22 Model 8903 Performance Tests PERFORMANCE TESTS B903E DISTORTION ANALYZER GROUND INDICATOR Figure 4 4 Input Impedance Test Setup 6 Press RATIO twice to establish a new reference 7 Insert the 100kQ resistor in series with the inner conductor of the audio oscillator s output The right display should read between 49 90 and 50 40 if the audio oscillator has 6000 output impedance or between 49 00 and 51 0096 if the audio oscillator has 500 output impedance Display with 6000 Impedance 49 90 50 40 Display with 500 Impedance 49 00 51 00 4 23 Performance Tests Model 8903E PERFORMANCE TESTS 4 13 COMMON MODE REJECTION RATIO PERFORMANCE TEST SPECIFICATION Characteristic Performance Limits Conditions GENERAL Common Mode Rejection Differential input lt 2V 20 to 1000 Hz Ratio Differential input gt 2V 20 to 1000 Hz 1 to 20 kHz DESCRIPTION The output from an external audio oscillator is connected to both inner and outer conductors of the Distortion Analyzer s input connector The outer conductor is set to float The ac level of
106. ance Test Record 4 of 10 AC LEVEL ACCURACY PERFORMANCE TEST Cont d cont d High Level Low Input AC Level Accuracy Cont d Level Low input High Level Low Input AC Level Accuracy Cont d Level Accuracy Cont d AC Calibrator Commands OUTPUT 728 Frequency SP Hz 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 Synthesizer Displayed Frequency Reading of Hz Step b Low Level Low Input AC Level Accuracy 2 b 20 000 100 000 Low Level High input AC Level Accuracy 100 000 20 000 2 000 20 4 29 Performance Tests Model 8903E Table 4 1 Performance Test Record 5 of 10 DC LEVEL ACCURACY PERFORMANCE TEST High Input DC Level Accuracy DC Standard Voltage 300 Vdc 297 75 Vdc 302 25 Vdc 30 Vdc 29 775 30 225 Vdc 3 Vdc 2 9775 Vdc 3 0225 Vdc 0 4 Vdc 0 397 Vdc 0 403 Vdc 0 04 Vdc 0 037 Vdc 0 043 Vdc Low Low nput DC Level Accuracy DC Level Low nput DC Level Accuracy DC Standard Voltage 0 04 0 054 0 043 Vdc 0 4 Vdc 0 594 0 403 Vdc 3 2 9775 3 0225 30 Vdc 29 775 30 225 Vde 300 297 75 Vde 302 25 Vdc Audio Oscillator Oscillator LOW En PASS Hz FILTER 1 in 1 000 1 000 1 000 20 000 50 000
107. and indicators remote and local opera tor s checks operating instructions and operator s maintenance 3 3 Operating Characteristics Table 3 1 briefly summarizes the major operating characteristics of the Distortion Analyzer The table is not intended to be an in depth listing of all opera tions and ranges but gives an idea of the instrument s capabilities For more information on the Distortion Analyzer capabilities refer to the description in Sec tion 1 Table 1 1 Specifications and Table 1 2 Sup plemental Information For information on HP IB capabilities refer to the summary contained in Table 3 3 Message Reference Table N 3 4 Turn On Procedure Before the Distortion Analyzer is switched on all protective earth terminals extension cords auto transformers and devices con nected to it should be connected to a pro tective earth socket Any interruption of the protective earth grounding will cause a potential shock hazard that could result in personal injury In addition verify that common ground exists between the unit under test and the Distortion Analyzer prior to energizing either unit For continued protection against fire haz ard replace the line fuse with a 250V time delay fuse of the same rating Do not use repaired fuses or short circuited fuseholders To avoid the possibility of hazardous elec trical shock the input signal voltage on the outer connector referenced to ground is not to
108. and some safeguards remain in effect unless the operator disables them These Special Functions are described below Prefixes 40 to 99 These are the Service Special Functions used to assist in troubleshooting an instrument fault The functions available are quite diverse special internal measurements software control and special service tests and configurations Most instrument safeguards are relinquished These Special Functions are discussed in detail in Section 8 If a Service Special Function is entered inadvertently enter Automatic Operation AU over the HP IB Viewing Special Function States The operator requested settings of Special Functions prefixed 1 through 8 may be viewed by pressing the S Shift Notch Tune keys once This display is called the Special Display If some of these Special Functions are in automatic modes generally the O suffix setting the actual instrument settings of these functions may be displayed by pressing the S Shift Notch Tune keys a second time while the Special Display is active This display is called the Special Special Display If desired these displays can be cleared by pressing any key except the LCL or S Shift keys A summary of User Special Functions is given on the following pages Following the summary are procedures for using Special Display These displays are also illustrated and explained NOTE The following special functions are ignored 7 0SP 7 1SP 8 2SP 10 0SP 12 1SP throug
109. andle kit and a rack flange kit packaged together it is composed of a unique part which combines both functions Order HP part number 5061 9683 1 14 HEWLETT PACKARD INTERFACE BUS HP IB 1 15 Compatibility The Distortion Analyzer is compatible with HP IB to the extent indicated by the following code SH1 AH1 T5 L3 LEO SR1 RL1 DT1 CO El The Distortion Analyzer interfaces with the bus via open collector TTL circuitry explanation of the compatibility code can be found in IEEE Standard 488 IEEE Standard Digital Interface for Programmable Instrumentation or the identical ANSI Standard MC1 1 For more detailed information relating to programmable control of 1 4 Model 8903E the Distortion Analyzer refer to Remote Operation Hewlett Packard Interface Bus in Section 3 of this manual 1 16 Selecting the HP IB Address The HP IB address switches are located within the Distortion Analyzer The switches represent a five bit binary number This number represents the talk and listen address characters which an HP IB controller is capable of generating In addition two more switches allow the Distortion Analyzer to be set to talk only or listen only table in Section 2 shows all HP IB talk and listen addresses Refer to HP IB Address Selection in Section 2 of this manual 1 17 ACCESSORIES SUPPLIED The accessories supplied with the Distortion Analyzer are shown in Figure 1 2 Tim
110. asurement Block Diagram on next page 3 45 Operation Model 8903E Distortion Level cont d Measurement Technique cont d COUNTER LEFT DISPLAY ee FREQUENCY MONITOR HP BP OUTPUT INPUT FILTERS NOTCH RMS AVG NPUT ATTENUATOR AMPLIFIER T LP VOLTMETER RIGHT DISPLAY pas p ert CONTROLLER BAA AMS DETECTOA Distortion Level Measurement Block Diagram Related Detector Selection Sections Distortion Filters Monitor Notch tune RATIO and LOG LIN 3 46 4 8903 Description Procedure Example Program Code indications Comments Related Sections Operation Error Disable Special Function 8 The Error Disable Function is used to selectively disable operating error messages Using the 8 N Special Function allows the user to enable all operator error messages or disable analyzer errors measurement related errors To selectively disable or enable operator error messages enter the corresponding HP IB code Error Message Status 4 ode All error messages enabled 8 0SP Disable analyzer error messages 8 1SP or 8 3SP To disable the analyzer error messages x 8 1SP Code NR M m program codes For HP IB codes refer to Procedure above the program code is entered both displays will blank and the entered code will flash in the left display Both displays return to the display that is appropriate for the currently selected measureme
111. cal operation Trigger Immediate T2 When the Distortion Analyzer receives the Trigger Immediate code it akes one measurement in the shortest possible time he instrument then waits for the measurement results to be read While waiting the instrument can 3 23 Operation ex process most bus commands without losing the measurement results However if the instrument re ceives GTL Go To Local GET Group Execute Trigger or its listen address or if it is triggered by the Clear Key Function a new measurement cycle will be executed Once the data measurement results are read onto the bus the Distortion Analyzer reverts to the Hold mode Measurement results obtained via Trigger Immediate are normally valid only when the instrument is in a steady settled state Trigger with Settling T3 Trigger with Settling is identical to Trigger Immediate except the Distortion Analyzer inserts a settling time delay before taking the requested measurement This set tling time is sufficient to produce valid accurate measurement results Trigger with Settling is the trig ger type executed when a Trigger message is received via the bus Triggering Measurements with the Clear Key Function When the Distortion Analyzer is in remote Hold and not in Local Lockout the front panel Clear Key Function may be used to issue a Trigger with Settling instruction First place the instrument in Hold mode code T1 Trigger the measurement by
112. can also be made using a variety of adapters and Jumper cables in place of the stripped RF coaxial cable 4 Using the controller key in and execute the Special Function indicated in the table below Set the audio oscillator to the frequency listed For each setting the right display should read within the limits indicated Controller Oscillator AC Level Limits mV Commands Frequency OUTPUT 728 Hz 1 12SP 1 1 SP 4 25 Performance Tests Model 8903 Table 4 1 Performance Test Record 1 of 10 Hewlett Packard Company 8903E Tested by Audio Analyzer Serial Number Para No Test Description AC LEVEL ACCURACY PERFORMANCE TEST High Level High input AC Level Accuracy Controller AC Calibrator Commands Frequency Hz OUTPUT 728 SP 20 102 2 000 102 20 000 102 100 000 104 100 000 104 20 000 102 2 000 102 20 102 20 102 2 000 102 20 000 102 100 000 104 100 000 104 20 000 102 2 000 102 20 102 20 102 2 000 102 20 000 102 100 000 104 100 000 104 20 000 102 2 000 102 20 102 20 102 2 000 102 20 000 102 100 000 104 100 000 104 20 000 102 2 000 102 20 102 20 102 2 000 102 20 000 102 100 000 104 100 000 20
113. ckout entes Data Messages Receiving the Data Message Lasten Only Data Input Format Program Codes Turning Off Functions Programming Numeric Data General Numeric Data Input Format Triggering Measurements with the Data Message Special Considerations for Triggered Operation Reading Data from the Right or Left Display Program Order Considerations Sending the Data Message Talk Only Mode Talk Status Only Mode Data Output Format Data Output Format Error Output Format Receiving the Clear Message Receiving the Trigger Message Receiving the Remote Message Receiving the Local Message Receiving the Local Lockout Message Receiving the Clear Lockout Set Local Message Receiving the Pass Control Message Sending the Require Service Message Selecting the Service Request Condition ees Pao Sending the Status Byte Message Sending the Status Bit Message TECTA i D LL Receiving the Abort Message HP IB Syntax and Characteristics Summary Page Page DETAILED OPERATING IN
114. controlled functions are being properly executed by the Distortion Analyzer HP IB Functional Checks This series of procedures requires an HP IB compatible computing controller and an HP IB interface and connecting cable The HP IB Functional Checks assume that front panel operation has been verified for example by perform ing the Basic Functional Checks The procedures check all of the applicable bus messages summarized in Table 3 3 3 8 Operator s Maintenance For continued protection against fire haz ard replace the line fuse with a 250V time delay fuse of the same rating only Do not use repaired fuses or short circuited fuseholders ENDE eS SS SS ee Model 8903E Operation The only maintenance the operator should normally NOTE perform is the replacement of the primary power fuse located within the Line Power Module 14 For If the instrument does not operate properly and is being returned to Hewlett Packard for service please complete one of the blue repair tags located at the end of this man instructions on how to change the fuse refer to Figure 2 1 steps 1 and 3 in Section 2 Installation Fuses may be ordered by looking up the reference ual and attach it to the instrument Refer designator F1 in Section 6 Replaceable Parts and to paragraph 2 15 in Section 2 for packag ordering the correct part number for 100 120 Vac or ing instructions for 220 240 Vac operation both fuses are 250V time delay
115. ction fundamental removed 1 15 General Information Model 8903E Table 1 3 Recommended Test Equipment instrument Type Critical Specifications Suggested Model Use AC Calibrator Accuracy 0 5 7 mV to 300V 20 Hz to 100 kHz HP 745A and P A Flatness 0 196 20 Hz to 100 kHz lt 6V HP 746A Output Current 60 mA Datron 4200 or Frequency Accuracy 5 Fluke 5200A and Fluke 5215A Audio Synthesizer Frequency Range 20 Hz to 500 kHz HP 3336C Frequency Accuracy 4ppm Output Range into 6000 Output Attenuation Accuracy 0 075 dB to 0 3 mV range Computing HP IB compatibility as defined by IEEE Std 488 and the HP 9825A C T Controller DC Standard Digital Voltmeter identical ANSI Std MC1 1 SH1 AH1 2 L2 LEO SRO PPO DCO and C1 2 3 4 5 98034A 98213A or HP 85B Opt 007 Output Range 3 mV to 300V Accuracy 0 196 0 3 mV HP 740B or Datron 4000 or Fluke 893AR AC Accuracy 0 296 at 6 Vrms 1 kHz DC Accuracy 40 296 at 1V Frequency Standard Oscilloscope Power Supply Output to 15 HP 6215A Resistor 100k2 Accuracy 0 1 HP 0698 7497 EN HP 5005 HP 3310A 3403 7 Operator s Checks Performance Tests Adjustments Troubleshooting Frequency 0 1 1 2 5 or 10 MHz Accuracy 1 ppm Bandwidth lt 3 dB down 0 to 10 MHz Sen
116. d HP IB code Check for compatibility of functions selected sequence Invalid Special Function Check then re enter correct Special Function code prefix Refer to Special Functions Invalid Special Function Check then re enter correct Special Function code suffix Refer to Special Functions Invalid HP IB code Check then re enter correct HP IB code This error ex causes a Require Service message to be sent on the HP IB Refer to Table 3 4 and accompanying text 65 89 Refer to paragraph 8 12 Service Errors Related Automatic Operation Sections RATIO and LOG LIN 3 50 Model 8903 Description Procedure Example Program Codes Indications Comments Operation Filters High Pass Bandpass Low Pass The optional plug in high pass and weighting bandpass and the LP low pass FILTER keys cause the respective filters to be inserted into the audio signal path The filters limit the measurement bandwith The high pass and bandpass filters are inserted before the notch filter control of the notch filter is covered in the Notch Tune discussion The low pass filters are inserted after the notch filter When in use the high pass bandpass and low pass filters always affect the signal at the MONITOR output Select the desired signal filters by pressing the appropriate keys Only one high pass or bandpass and one low pass filter can be in use at a time To turn a filter off press the key again or selec
117. d ground Between low input and ground Except in dc leve mode In dc level mode only Each terminal to ground 20 Hz to 1 kHz Viu 2V 20 Hz to 1 kHz 20 Hz to 20 kHz The Hewlett Packard Interface Bus HP IB is Hewlett Packard Company s implementation of IEEE Std 488 1978 Digital Interface for Programmable Instrumentation All func tions except the line switch and the low terminal float ground switch are remotely controllable TT I LLNLLLIO Model 8903 General Information Table 1 1 Specifications 4 of 4 Performance Limits Sonton POWER REQUIREMENTS Line Voltage 100 120 220 240 Vac 5 10 48 to 66 Hz 100 120 Vac 5 10 48 to 440 Hz POWER DISSIPATION 100 V A maximum CONDUCTED AND MIL STD 461B Conducted and radiated interference is within the RADIATED requirements of methods CEO3 and REO2 of MIL STD 461B INTERFERENCE EMI and FTZ 526 527 CONDUCTED AND MIL STD 461B 1980 Conducted and radiated susceptiblity meets the requirements RADIATED of methods 501 CS02 and RS03 SUSCEPTIBILITY 1 volt meter of MIL STD 461B dated 1980 NET WEIGHT 11 8 kg 26 Ib Net 15 9 kg 35 Ib Shipping DIMENSIONS Full Envelope Height 146 mm 5 75 in Note For ordering cabinet accessories the module sizes are Width 425 mm 16 8 in 514H 1MW x 17D Depth 462 mm 18 2 in Table 1 2 Supplemental Information All parameters describe performance in automatic operation or with p
118. decrease A2C4 by approximately 10 If the 40 kHz reading is higher than that at 100 kHz increase A2C4 by approximately 10 On the Distortion Analyzer press RATIO to turn it off Set the ac calibrator frequency to 1 kHz and level to 15 Vrms The right display of the Distortion Analyzer should read between 14 7 and 15 3V Check that the input is on range 7 by pressing S Shift NOTCH TUNE Shift NOTCH TUNE The first digit of the left display should be 7 Press AC LEVEL Press RATIO Set the ac calibrator frequency to 40 kHz Adjust A2C10 HIGH 24 DB for a reading on the right display between 99 70 and 100 3 Set the ac calibrator frequency to 100 kHz Adjust A2C10 for a reading between 99 50 and 100 5 Repeat steps 10 and 11 as often as needed until the flatness at 40 kHz and 100 kHz is within the limits given NOTE If the flatness cannot be adjusted so that the 40 kHz and 100 kHz readings are both within the given limits change 2 9 as follows If the 100 kHz reading is higher than at 40 kHz decrease A2C9 by approximately 10 If the 40 kHz reading is higher than that at 100 kHz increase A2C9 by approximately 10 On the Distortion Analyzer press RATIO to turn it off Set the ac calibrator frequency to 1 kHz and level to 60 Vrms The right display of the Distortion Analyzer should read between 58 8 and 61 2V Check that the input is on range 4 by pressing S Shift NOTCH TUNE 5 Shift NOTCH TUNE The first digit of
119. e enter the corresponding HP IB program code As the program code is entered it will appear on the left display The display returns to show the input signal frequency 8903E Operation Input Level Range Except DC Level Cont d Special Function 1 Comments When the Distortion Analyzer is first powered up or when Automatic Operation is selected the input level range is placed in the automatic selection mode If the input level range is set such that the input signal level creates an overrange condition an error message will be displayed The error message generated depends on instrument settings and the input signal level For example if the input level range is set such that the input signal level causes the input overload detector to trip Error 30 will be displayed For a complete listing of the error messages refer to Error Message Summary Manually selecting the gain of the input level circuitry can cause measurement error Measurement accuracy is not specified whenever the gain of the input level circuitry is manually selected because the selected gain setting may be less than optimum It is important to note that error messages indicating invalid measurements due to incorrect gain settings are not generated unless overload conditions occur Automatic operation ensures accurate measurements for all combination of input signals and measurement modes Related AC Level Sections Automatic Operation I
120. e AVG RMS Detector Monitor etc Also included are in structions for using the many User Special Functions for example Hold Settings Error Disable Special Functions etc The Detailed Operating Instructions are indexed by function in Table 3 2 Each section contains a general description which covers signal levels ranges and other general informa tion Following the description are related procedures an operating example the relevant HP IB codes front panel indications and where pertinent a description of the technique the Distortion Analyzer uses to make the measurement t the end of each discussion are comments intended to guide the user away from measurement pitfals and to help get the most out of the Distortion Analyzer Also included are refer ences to other sections which contain related informa tion The Detailed Operating Instructions are de signed so that both casual and sophisticated users can rapidly find at one location all the information needed to apply the instrument to the task at hand Supplemental Information In addition to the infor mation described above several other discussions per tinent to the operating of the Distortion Analyzer to its fullest capabilities are contained in Section 1 of this manual Principles of Operation for a Simplified Block Diagram is a fundamental description of what the Distortion Analyzer is and how it works This information supplements the block diagrams given in
121. e reciprocal of the distortion measurement It is usually expressed indB The notch filter is coarsely pro grammed to the input frequency by the microproces sor but fine tuned to the signal at its input When measuring SINAD in the presence of large amounts of impurities a front panel key locks the coarse tuning of the notch filter at the correct input frequency SINAD is an acronym for SIgnal Noise And Distortion The ratio normally expressed in dB com puted in the SINAD measurement is rms value of signal noise and 1 rms value of noise and distortion The equation eliminates the two restrictions discussed connection with the distortion measurement SINAD is used most often in determining the sensitiv ity of a receiver Receiver sensitivity is defined as the RF level that when modulated in a specified manner with a pure audio tone creates a certain SINAD usually 10 or 12 dB at the receiver s audio output The tone can just be discerned in the noise Sometimes a noise weighting filter is required in the receiver sensitivity measurement Optional plug in Weighting Filters modify the frequency response of the Distortion Analyzer with a bandpass characteris tic that approximates the response of human hearing Weighting Filters which meet most international standards are available Model 8903 General Information SIN X AND 0 05 SIN 2X SIN X AND 0 05 COS 2X SIN X 0 05 SIN 2X SIN X
122. e Run All LP Filters off Hold 30 kHz LP Filter on Trigger Immediate 80 kHz LP Filter on Trigger with Settling AC Level minus SINAD 0 9 Distortion decimal point Automatic Notch Tuning Notch Hold Not to be confused with Clear message which is defined in Table 3 3 3 30 8903 Operation x Table 3 8 Distortion Analyzer Special Function to HP IB Code Summary Special Function Program Code Special Function Program Code Input Level Range except DC Level Automatic Selection 300V range 189V range 119V range 75 4V range 47 6V range 30 0V range 18 9V range 11 9V range 7 54V range 4 76V range 3 00V range 1 89V range 1 19V range 0 754V range 0 476V range 0 300V range 0 189V range 0 119VV range 0 0754V range Input Level Range DC Level only Automatic Selection 300V range 64V range 16V range 4V range Post Notch Gain Automatic Selection 0 dB 20 dB gain 40 dB gain 60 dB gain Hold Decimal Point Automatic Selection DDDD range DDD D range 00 00 range D DDD range 0 0000 range DD DD mV range D DDD mV range 0 DDDD mV range Post Notch Detector Response except in SINAD Fast RMS Detector Slow RMS Detector Fast AVG Detector Siow AVG Detector Notch Tune Automatic notch tuning Hold notch tuning Error Disable All errors enabled 8 0SP Disabled Analyzer errors 8 1SPor Errors 12 17 31 and 96 8 3SP Disable External Source errors 8 25 Error 19
123. e are latched but can be cleared by 1 removing the causing condition and 2 reading the Status Byte The Distortion Analyzer does not respond to a parailel poll Status Bit The Distortion Analyzer stops talking and listening pm IFC T5 TEO BEI Commands Control lines and Interface Functions are defined in IEEE Std 488 Knowledge of these might not be necessary if your controller s manual describes programming in terms of the twelve HP IB Messages shown the left column Complete HP IB capability as defined in IEEE Std 488 and ANSI Std 1 1 is SH1 AH1 5 L3 LEO SR1 RL1 DC1 DT1 1 Local Lockout When a data transmission is inter rupted which can happen by returning the Distortion Analyzer to local mode by pressing the LCL key the data could be lost This would leave the Distortion Analyzer in an unknown state To prevent this a local lockout is recommended Local lockout disables the LCL key and the Clear Key Function S Shift AVG RMS and allows return to local only under program control NOTE Return to local can also be accomplished by turning the Distortion Analyzer s LINE switch to OFF then back to ON However this technique has several disadvantages It defeats the purpose and advantages of local lockout that is the system control ler will lose control of a system element There are several HP IB conditions that reset to default state
124. e delay fuses with a 1 5A rating for 100 120 Vac operation HP 2110 0059 and a 0 75A rating for 220 240 Vac operation HP 2110 0018 are supplied One fuse is installed in the instrument at the time of shipment The rating of the installed fuse is selected according to the line voltage specified by the customer If the voltage is not specified the rating of the in stalled fuse will be selected according to the country of destination For Option 001 only two type BNC to banana plug adapters HP 5021 0844 are also supplied for use when double ended inputs or outputs are desired The conductor of the banana jack is connected to the center conductor of the BNC adapter connector These adapters are used when the front panel INPUT or OUTPUT FLOAT switches are set to FLOAT 1 18 ELECTRICAL EQUIPMENT AVAILABLE Also refer to Service Accessories Table 1 4 1 19 HP IB Controllers The Distortion Analyzer has an HP IB interface and can be used with any HP IB compatible computing controller or computer for automatic systems applications 1 20 Front to Rear Panel Connectors Retrofit Kit This kit contains all the necessary components and full instructions for converting instruments with front panel connections for INPUT and MONITOR to rear panel connections Order HP part number 08903 60177 After installation and calibration per formance will be identical to the HP 8903E Option 001 Model 8903E General Information SPARE IN
125. e oscilloscope 3 Set the oscilloscope s vertical sensitivity to view the Distortion Analyzer s time base reference or the frequency standard output Set the horizontal scale for 0 1 us per division Set the oscilloscope to trigger externally 4 Adjust A8C27 for a waveform movement of 10 divisions per second or less A totally non metallic adjustment tool is recommended NOTE A movement of the waveform to the right or left if the oscilloscope connections are reversed at rate of one division per second means that the Distortion Analyzer s time hase frequency 15 low by 0 1 ppm Adjustments Model 8903E ADJUSTMENTS 5 8 INPUT FLATNESS ADJUSTMENT Reference Service Sheet 1 Description An ac calibrator is connected to the input of the Distortion Analyzer The Distortion Analyzer is set to measure ac level The frequency of the calibrator is varied between 1 40 and 100 kHz and the flatness adjusted is for a constant level at all three frequencies The procedure is repeated for two other input ranges The entire procedure is run with the outer conductor of the input connector grounded then with the inner conductor grounded and the signal applied to the ungrounded outer conductor Voltages up to 60 Vrms will be applied to the Distortion Analyzer s input connector and will be present on the assembly being adjusted Do not extend the assembly or probe its circuitry when high voltage is applied to the input Equip
126. ement that is attenuate the second oscillator s output level as indicated d Set the low distortion oscillator level to 6V The display on the Distortion Analyzer should read within the limits indicated Second Oscillator Low Distortion Level dB Oscillator 4 On the Distortion Analyzer set the 80 kHz LOW PASS FILTER off Repeat step 3 for the settings indicated below Second Oscillator Level dB Low Distortion Oscillator Frequency Hz 100 000 100 000 200 000 10 60 60 10 200 000 100 000 100 000 300 000 300 000 4 13 Performance Tests Model 8903E PERFORMANCE TESTS 4 10 FREQUENCY ACCURACY AND SENSITIVITY PERFORMANCE TEST SPECIFICATION Performance Limits Conditions FREQUENCY Measurement 20 Hz to 150 kHz AC level mode Range 20 Hz to 100 kHz Distortion and SINAD modes Accuracy 0 004 1 digit Sensitivity 50 mV Distortion and SINAD modes 5 mV AC level mode DESCRIPTION The frequency of an audio synthesizer is measured at various levels with the Distortion Analyzer s counter EQUIPMENT Audio Synthesizer HP 3336C NOTE The audio synthesizer s time base accuracy must be 4 ppm or better PROCEDURE 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground Set the 80 kHz LOW PASS FILTER off 2 Connect the audio synthesizer s output
127. ems applications involve measuring low level ac signals The Distortion Analyzer features a full range ac level display of 0 3000 mV with an accuracy of 4 of reading 2 of reading for levels 250 mV and from 20 Hz to 20 kHz The ac detector is switchable between true rms and average respond ing detection The 3 dB measurement bandwidth for both detectors is greater than 500 kHz Since many systems have noise problems the Distortion Analyzer has both 30 and 80 kHz low pass filters to reject high frequency noise In addition the optional internal plug in 400 Hz high pass filter atten uates line related hum and noise by more than 68 dB special binary programming mode is available in remote operation The rapid frequency count mode provides a packed four byte output for fast counting over HP IB 1 11 OPTIONS 1 12 Electrical Options Electrical Option 001 This option provides a rear panel instead of front panel connection for the INPUT and MONITOR connectors Internal Plug in Filter Options The Distortion Analyzer has two internal plug in filter positions each position can be loaded with any one of six optional filters Each filter is referenced to its corre sponding filter position by one of two option numbers For example the 400 Hz High Pass Filter Option can be ordered as Option 010 which corresponds to the left most filter position or as Option 050 which corre sponds to the right most filter position These op ti
128. ent mode and input Comments The converse of the automatic operation mode is the Hold Settings Special prefixed 9 Refer to Hold Settings For information on which specific Special Functions are turned off by the Automatic Operation mode refer to Special Functions Since Automatic Operation affects Special Functions it is a good practice to place the AU code at the beginning of a program string when programming the instrument Related Hold Settings Sections Special Functions 3 35 Operation Description 3 36 Model 8903E Common Mode Common mode rejection ratio or common mode as it is usually referred to is a measure of the ability of an amplifier to reject signals that are common to both amplifier inputs while allowing the differential signals which may or may not be the weaker signal to be amplified and passed on to the measurement circuitry Since the analyzer input is fully balanced it can reject signals which are common to the High and Low Inputs with the INPUT FLOAT switch in the FLOAT position For standard instruments the High Input is the center conductor of the INPUT BNC connector the Low Input is its outer conductor For instruments with Option 001 the High and Low Inputs are the center conductors of the respective HIGH and LOW INPUT connectors However for valid measurement results there are limitations to the maximum level of common mode signals To avoid the possibility of hazardous shoc
129. equire Service message pending will be cleared if a Clear message is received If the instrument is set to Talk Only the Status Byte is cleared each time the one byte Data message is issued to the bus 3 30 Sending the Status Bit Message The Distortion Analyzer does not respond to a Paral lel Poll Enable PPE bus command and thus cannot send the Status Bit Message 3 31 Receiving the Abort Message The Abort Message is the means by which the control ler sets the Interface Clear IFC bus control line true When the Abort message is received the Distortion Analyzer becomes unaddressed and stops talking or listening 3 27 Operation lt lt START 8903E SET TRIGGER MODE TO HOLD HP 1B CODE T1 ENABLE SRQ ON DATA READY HP 1B CODE 22 3SP CONF GURE MEASUREMENT TRIGGER MEASUREMENT HP 18 CODE T2 OR T3 PROCESS OTHER ROUTINES UNTIL SRQ CAUSES INTERRUPT Figure 3 4 Example Flow Chart for Driving the Distortion Analyzer Using the Require Service Message SRQ 3 28 Model 8903E INTERRUPT ON SRQ READ STATUS BYTE FROM 8903E SRQ FROM 8903E TO OTHER INSTRUMENT SERVICE ROUTINES 8903E SRQ DUE TO DATA READY TEST OTHER 8903E SRQ CONDITIONS READ DATA FROM 8903E RETURN ERN ALME LC CL LLL 1L JA JUD Model 8903E Operation HP IB SYNTAX AND CHARACTERISTICS SUMMARY Address Set in binary by internal switches may be displayed on front pa
130. f 10V is on the analyzer s input with a 1V differential signal the ranging detector selects the 1 19V range The signal that is present at the input is actually 11V 10V common mode signal the 1V differential signal A voltage signal this large can exceed the input amplifiers operating range and cause erroneous measurements However the instrument will not be damaged because the Over voltage Protection circuitry will open whenever the combined common mode and differential signals exceed the instrument s safe operating range Setting Special Function 1 8 will set the input range to 11 9V Comments For error free measurements the Operating Region For Valid Measurements graphs shown below indicate the maximum allowable common mode input voltages for a given differential input voltage Case 1 is for a single ended source with a common mode signal present on both input lines Case 2 is for a balanced source with common mode signals on both input lines To obtain the maximum common mode input voltage level from the graphs select the desired value for the differential input voltage Then read the common mode input voltage level For example on the Case 1 graph for a differential input voltage level of 1V the maximum common mode input voltage level is 2 8V For a differential input voltage of 20V the maximum common mode input level is 20V OPERA VALID MEASUREMENTS INSTRUMENT IN AUTOMATIC OPERATION e lt H gt
131. frequency data will be in the form shown below BYTE 1 BYTE 2 BYTE 3 BYTE 4 BBBB BBBB BBBB BBBB BBBB BBBB XXBB BBBB ioni eee 260 minus _ 255 minus 2 number of Least significant number of Most significant clock carries digit LSD of cycle carries digit MSD of clock count clock count Second least significant Cycle count digit 2LSD of clock count To obtain the frequency compute Total clock counts LSD 16 2LSD 256 MSD 1024 260 BYTE 1 Total cycle counts Cycle count 16 255 BYTE 3 Total cycle counts 5 Total clock counts X 42 105 Frequency Where LSD Least significant digit of clock count 2LSD Second least significant digit of clock count MSD Most significant digit of clock count Using a BASIC controller such as the Hewlett Packard Model 85B Desktop Controller the computation is set up in seven steps as shown below 10 OUTPUT 728 USING 46 1SPT3 RF 20 ENTER 728 USING B A B C D 30 T IP B 16 16 BINAND B 15 16 BINAND D 48 1024 260 A 40 E BINAND D 15 16 255 C 50 F IP E T 200000000 100 60 DISP F 70 END 3 70 Model 8903 cont d Operation Rapid Frequency Count cont d Explanation Line 10 Places the Distortion Analyzer in the Rapid Count Mode 46 1SPT3 sets up the analyzer for transient free operation Line 20 Enter the four rapid count bytes using the Binary format B Line 30 Calculate T
132. front panel and includes the Input and Output RMS Average Detectors dc voltmeter the Voltage to Time Converter and Counter Measurements are made on HP BP FILTERS PROGRAMMABLE PROGRAMMABLE GAIN AMPLIFIER LP FILTERS AMPLIFIEA Fe MONITOA INPUT AMS DETECTOR OUTPUT RMS DETECTOR Figure 1 3 Simplified HP 8903E Distortion Analyzer Block Diagram 1 6 Model 8903E the difference between the signals on the inner conductor and shield of the INPUT connector or for option 001 the HIGH and LOW connectors Com bined differential and common mode levels can be as high as 300 However for safety purposes only 42V maximum is allowed on the outer conductor of the single BNC input connector when in the FLOAT position The input signal is ac coupled for all measurement modes except dc level The signal is scaled by the Input Attenuator to a level of or less protect the active circuits that follow the Over Voltage Pro tection circuit opens whenever its input exceeds 15V The differential signal is converted to a single ended signal that is a signal referenced to ground and amplified In the dc level mode the dc voltage is measured at this point by the dc voltmeter The signal is further amplified by a Programmable Gain Amplifier which is ac coupled The gain of this ampli fier and the Differential to Single Ended Amplifier are programmed to keep the signal level going into the Input Detector and Notc
133. ge DD DD mV Range D DDD mV Range 0 0000 mV Range The decimal point does not appear on the display It is shown to establish the position it would appear in the numeric value of the readout zero does not appear on the display It is shown to clarify the position of the decimal point Example To hold the decimal point after the first digit of a mV Range D DDD mV x 4 7SP Te PEDE NOS program codes Program Codes For HP IB codes refer to Procedure above Indications As the program code is entered both displays will blank and the entered code will flash in the left display The right display will show the amplitude with the decimal held in the position requested The left display provides the normal information associated with the selected measurement mode Comments It is possible to use the Hold Decimal Point Special Function to set the display for a readout that exceeds the resolution of the instrument For example in the dc level measurement mode 4 7SP will set the display to a mV range In this case the three digits following the decimal point will always be zeros and are not significant digits in the amplitude readout Related Automatic Operation Sections Special Functions 3 57 Operation Description Procedure Example Program Code Indications Comments Related Sections 3 58 Model 8903E Hold Settings Special Function 9 The Hold Settings Special Function is used
134. ger Immediate and Trigger with Settling T2 and T3 When either of the trigger codes T or T3 is received by the Distortion Analyzer a measurement is immediately initiated Once the measurement is complete some bus commands can be processed without losing the measurement results However any HP IB program code sent to the Distortion Analyzer before the triggered measurement results have been output will initiate a new measurement Thus trigger codes should always ap pear at the end of a program string and the triggered measurement results must be read before any addi tional program codes are sent 3 19 Sending the Data Message Depending on how the internal address switches are set the Distortion Analyzer can either talk only talk status only listen only or talk and listen both normal operation If set to both talk and listen the instru ment sends Data messages when addressed to talk The instrument then remains configured to talk until it is unaddressed to talk by the controller To unaddress the Distortion Analyzer the controller must send either an Abort message new talk ad dress or a universal untalk command 8903 Talk Only Mode If the internal address switches are set to a valid Talk address and the TON Talk Only switch is set to 1 the Distortion Analyzer is placed in the Talk Only mode In this mode instrument is configured to send Data messages whenever the bus is in the data mode Eac
135. gram Code Format x Binary 21 0 SP Decimal 21 1 SP As the program code is entered it will appear on the left display When the HP IB code is entered the top row measurement key lights and annunciators will turn off If the 21 0 Special Function was entered the left display will show a binary number of the form AAAAA where AAAAA is the HP IB address in binary The right display will show a binary number of the form TLS where the T L and S have the meaning indicated in the table on the following page LISTEN REQUESTING ONLY SERVICE ONLY ONLY SERVICE If T and L are both 1 the instrument is set to talk only talk overrides listen If all the digits are set to 1 and T is 1 the instrument will be in talk status only that 1s output the status byte only If all digits AAAAA TL are 1 but S is 0 the Remote Interface board is not installed If the 21 1 Special Function was entered the left display will show the statement Addr and the right display will show the decimal value of the instrument s HP IB address 28 if it has not been changed Remote Operation Hewlett Packard Interface Bus Special Functions Model 8903E Description Procedure Example Program Codes indications Comments Related Sections Operation Input Level Range DC Level Special Function 2 In all measurement modes the input level range can be set to a desired range by using Special Function 2 N through HP
136. h 12 9SP 13 0SP 13 1SP and 17 1SP through 17 9SP The instrument will accept the above HP IB codes with the possibility of an erroneous display but they will not result in a measurement Model 8903 Operation Special Function Summary 1 of 3 Special Function Disable Code Description Input Level Range except DC Level Automatic selection 300V range 189V range 119V range 75 4V range 47 6V range 30 0V range 18 9V range 11 9V range 7 54V range 4 76V range 3 00V range 1 89V range 1 19V range 0 754V range 0 476V range 0 300V range 0 189V range 0 119V range 0 0754V range Input Level Range except DC level LLK Input Level Automatic Selection Input Leve Range Range DC 300V range DC Level only Level only 64V range 16V range 4V range Automatic selection Post Notch Gain 0 dB gain 20 dB gain 40 dB gain 60 dB gain Post Notch Gain Automatic Selection Hold Decimal Point DDDD range Hold Decimal Point right display only DDD D range DD DD range Decimal Point not D DDD range displayed 0 0000 range DD DD mV range D DDD mV range 0 0000 mV range Leading zero not displayed Shown to clarify decimal point position Fast RMS Detector Slow RMS Detector Fast Average Detector Slow Average Detector Post Notch Detector Response Post No
137. h Filter between 1 7 and 3 Vrms This optimizes the effectiveness and accuracy of the amplifiers particularly in the distortion and SINAD modes The output from the first Programmable Gain Ampli fier is converted to dc by the Ranging RMS Detector and measured by the dc voltmeter The output of this detector is used to set the gain of the input circuits The signal then passes through the internal plug in HP BP filters to the input RMS Average detector and becomes the numerator of the SINAD measurement and the denominator of the distortion measurement refer to Basics of Audio Measurements The Input RMS Average Detector is not used to make the ac level measurement the Output RMS Average Detector is used for this measurement For dc level measurements the Ranging RMS Detector also monitors the ac component if there is one and lowers the gain of the input path if the signal will overload the input amplifiers otherwise the gain of the input path is determined by measuring the dc level At this point one of the two internal plug in filters can be inserted into the signal path The 400 Hz High Pass Filter is usually used to suppress line hum or the low frequency squelch tone used on some mobile transceivers The Weighting Filters have bandpass frequency responses that simulate the average re sponse of human hearing In the SINAD distortion and distortion level modes the frequency of the input signal is counted at the output of
138. h time the measurement is completed the measurement result will be output to the bus unless the listening device is not ready for data If the listener is not ready and the Distortion Analyzer is not in a trigger mode another measurement cycle is executed Talk Status Only Mode If all the internal address switches and the TON Talk Only switch are set to 1 but the LON Listen Only switch is set to 0 the Distortion Analyzer is placed in the Talk Status Only mode In this mode the instrument is configured to send a one byte data message whenever the bus is in the data mode The byte sent is an exact copy of the Status Byte Each time this byte is successfully sent on the bus the internal Status Byte is cleared The Data Valid DAV handshake line is pulsed each time the one byte Data message is sent Data Output Format As shown below the output data is usually formatted as a real constant in expo nential form first the sign then five digits leading zeros not suppressed followed by the letter E and a signed power of ten multiplier Refer to Rapid Frequency Count in the Detailed Operation Instruc tions for the only exception to this format The string is terminated by a carriage return CR and a line feed LF string positions 11 and 12 Data is always output in fundamental units for example Hz volts dB etc and the decimal point not sent is assumed to be to the right of the fifth digit of the mantissa
139. han 80 dB The output after the notch filter includes all harmonics of the fundamental plus any noise hum and other spurious signals that may be present These signal impurities are amplified and are available at the MONITOR output for further analysis The following equations express the MONITOR output level as a function of the parameter being measured the displayed reading Use linear Net Gain For distortion _ Displayed Reading in X Net Gain 100 or V 1 Reading in 08080 x X Net Gain ou in For distortion level Displayed Reading in volts X Net Gain or V 2 1ODisplayed Reading in dBm 20 x Net Gain out For SINAD s 00 X V X Net Gain Displayed Reading in 96 out Or V E 10 Displayed Reading in dB 1 20 x V x Net Gain In the above equations is the MONITOR output level as measured with a true rms voltmeter and is the input signal level The MONITOR output does not respond to dc signals presented at the INPUT In the dc level measurement mode only the ac components of the input signal are presented at the MONITOR output Related AC Level Sections DC Level Distortion Distortion Level Input Level Range DC Level Input Level Range Except DC Level 3 66 8903 Description Procedure Example Program Codes Indications Comments Related Sections Operation Notch Tune Special Function 6 In SINAD distortion and distortion leve
140. he controller automatically sets the input attenuation Technique and the gain of various amplifiers This is accomplished by measuring the signal with the ranging rms detector This control ensures that the signal amplitude is within the proper range of the input and output detectors The input detector converts the combined signal noise distortion ac signal to dc The notch filter then removes the fundamental signal and the output detector converts the noise distortion ac signal to dc The dc voltmeter measures both signals The controller then corrects for the programmed gain and attenuation computes the ratio and displays the results in the appropriate units The frequency of the input signal is also measured and displayed COUNTER LEFT DISPLAY FREGUENCY FREGUENCY LILI 9 VE 7 INTERNAL UCIN MONITOR HP BP OUTPUT FILTERS NOTCH RMS AVG LP VOLTMETER RIGHT OISPLAY ATTENUATOR FILTER OE TETOR CONTROLLER AMPLITUDE AMPLIFIER DETECTOR S N D RANGING RMS DETECTOR SINAD Measurement Block Diagram Comments During a SINAD measurement the output detector uses increased filtering to obtain more consistent readings in the presence of noise SINAD can be measured with either the true rms or average responding detector Most applications specify true rms detection The Distortion Analyzer powers up with Special Function 16 1 active for 0 0 dB resolution at all SINAD ratios Special Function 16 0 rounds the dig
141. he correct fuse is installed SAFETY EARTH GROUND An uninterruptible safety earth ground must be pro vided from the main power source to the product input wiring terminals power cord or supplied power cord set SAFETY SYMBOLS Instruction manual symbol the product will be marked with this symbol when it is necessary for the user to refer to the instruction manual refer to Table of Contents 2 Indicates hazardous voltages d Indicates earth ground terminal The WARNING sign denotes a hazard It calls attention to a procedure practice or the like which if not correctly performed or adhered to could result in personal in jury Do not proceed beyond a WARNING sign until the indicated conditions are fully understood and met The CAUTION sign denotes a haz ard It calls attention to an operating procedure practice or the like which if not correctly performed or adhered to could result in dam age to or destruction of part or all of the product Do not proceed beyond a CAUTION sign until the indi cated conditions are fully understood and met WARNING Any interruption of the protective ground ing conductor inside or outside the instru ment or disconnecting the protective earth terminal will cause a potential shock hazard that could result in personal injury Ground ing one conductor of a two conductor outlet is not sufficient protection Whenever it is likely that the protection has been impaired
142. hen Automatic Operation is selected NOTCH TUNE key light is off the Distortion Analyzer is placed in the automatic notch tuning mode In the automatic tuning mode the Distortion Analyzer counts the frequency of the input signal then coarsely tunes the notch filter to that frequency The notch filter is then fine tuned via circuitry internal to the notch filter In the hold tune mode the notch filter is no longer coarsely tuned however the fine tune circuitry still remains operational Thus the notch filter still automatically tunes but now over a limited range In the hold tuning mode the tuning or nulling range of the notch filter is approximately 5 of the frequency of the original notch filter setting Automatic Operation Distortion Distortion Level SINAD Special Functions 3 67 Operation Model 8903E Post Notch Detector Filtering Except SINAD Description Procedure Example Program Codes Indications Comments Related Sections 3 68 Special Function 5 The Distortion Analyzer normally makes audio measurements using a fast responding detector By means of HP IB program code entry additional Jow pass filtering can be added after the post notch detector The additional low pass filtering slow detector is useful in stabilizing measurements on unstable or noisy signals or whenever display jitter is considered excessive To change the Distortion Analyzer post notch filtering response from fast to sl
143. henever a Clear message is received and executed by the Distortion Analyzer or whenever a Controller Reset or Controller Clear Service Special Function is performed Automatic operation does not clear a Require Service message Procedure To enable one or more conditions to cause the Distortion Analyzer to issue a Require Service message sum the weights of the conditions to be enabled from the table below This sum becomes the code suffix of Special Function 22 Enter the special function code prefix decimal and suffix via the HP IB program code An HP IB code error weight 2 will always cause a Require Service message This condition cannot be disabled and if the weight is not summed in it will be assumed by the instrument Data ready HP IB code error Instrument error Example To set the Distortion Analyzer to send a Require Service message when an instrument error occurs or when an HP IB code error occurs first compute the special function suffix by summing the weights corresponding to those conditions 2 4 6 Then enter the code lt gt Function program codes Program Code Compute the special function code as described under Procedure above 3 76 Model 8903E indications Comments Related Sections Operation Service Request Condition cont d Special Function 22 As the HP IB program code is entered it will flash on the front panel display then the display returns to show the meas
144. ibed in IEEE Std 488 and ANSI Std MC1 1 SH1 T5 L3 LEO SR1 RL1 PPO DC1 DT1 El Instru ment Error For information on Rapid Frequency Count mode refer to it by name in the Detailed Operating Instructions 3 29 Operation Model 8903E Table 3 6 Distortion Analyzer Parameter to HP IB Code Summary Automatic Operation Ratio On SPCL Off SPCL SPCL Measurements Log Lin AC Level Log SINAD Lin Distortion DC Level Trigger Modes Free Run Hold Trigger Immediate Trigger with Settling Distortion Level RMS Detector AVG Detector Automatic Notch Tuning Notch Hold Miscellaneous Read Left Display Read Right Display Rapid Frequency Count Clear Key Function Internal Plug in HP BP Filters Left Plug in Filter on Right Plug in Filter on All Plug in HP BP Filters off LP Filters 30 kHz LP Filter on 80 kHz LP Filter on All LP Filters off Not to be confused with Clear message which is defined in Table 3 Table 3 7 Audio Analyzer HP IB Code to Parameter Summary RMS Detector Rapid Frequency Count AVG Detector Read Left Display Automatic Operation Read Right Display Ratio on Clear Key Function Ratio off All Internal Plug in HP BP Filters off SPCL Left Plug in Filter on SPCL SPCL Right Plug in Filter on DC Level Distortion Level Log Linear Fre
145. in the case of an ac to dc converter The Distortion Analyzer has dc level as one of its measurement modes 1 34 Signal impurities Distortion and SINAD are used to describe the impur ity content of a signal These terms are somewhat related and can often be confused pure signal is defined as a perfect sinusoid that is one whose frequency spectrum contains only a single spectral component Impurities are not always undesirable Impurities for example are what add character to the sound of musical instruments Pure signals in music sound monotonous However when testing a linear audio system if a pure signal is applied to the input anything but a pure signal at the output indicates that the system is degrading the signal There are several common classifications of impurities harmonic distortion har monics of the fundamental intermodulation distortion beat signals of two or more non related signals noise random signals and spurious signals for example line hum and interference All but intermodulation distortion are easily measured by the Distortion Analyzer 1 35 Distortion Harmonic distortion on a spectrally pure signal is created by non linearities in the circuit through which General Information it passes The non linearities can arise in the transfer characteristics of the active devices or by running the active device into saturation or cutoff Often distortion can be reduced by reducing the signa
146. ing digit blank The display for 1 12SP should be 12 with 2 in position 1 and 1 preceding it c Press AC LEVEL Compute the ratio of the reading in the right display to the calibrator setting The ratio should be within the limits indicated in the table Controller AC Calibrator Ratio Limits 96 Commands OUTPUT Level Vrms Frequency Hz Minimum Acus Maximum 1 15 300R1 20 2 000 20 000 100 000 4 2SP 150R1 100 000 20 000 2 000 20 1 35 100R1 20 2 000 20 000 100 000 1 4SP 70R1 100 000 20 000 2 000 20 1 55 45H1 20 2 000 20 000 100 000 1 65 30R1 100 000 20 000 2 000 20 Performance Tests PERFORMANCE TESTS Model 8903E 4 4 Controller Commands OUTPUT 728 1 7SP 15R1 1 85 10R1 1 95 7R1 1 10SP 4 5R1 1 11SP 3R1 1 128P 1 5R1 1 135 1R1 1 145 0 7R1 1 155 0 45R1 1 165 0 391 Frequency Hz 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 20 2 000 20 000 100 000 100 000 20 000 2 000 20 AC Calibrator Ratio Limits Model 8903 Performance Tests PERFORMANCE TESTS Commands OUTPUT 728 Level Vrms Frequency Hz 20 1 17SP 0 15R1 2 000 20 000 100 000 1 18SP 0 1R1 100
147. ion rapid frequency count capabilities not available from the front panel are provided in remote operation All the Special Functions and the distortion level measurement mode are available only through HP IB control A quick test of the HP IB I O is described under HP IB Functional Checks These checks verify that the Distortion Analyzer can respond to or send each of the applicable bus messages described in Table 3 3 For more information about HP IB refer to IEEE Standard 488 ANSI Standard MC1 1 the Hewlett Packard Electronic Systems and Instruments catalog and the booklet Improving Measurements in Engi neering and Manufacturing HP part number 5952 0058 3 13 HP IB Compatibility The Distortion Analyzer s complete bus compatibility as defined by IEEE Standard 488 and the identical ANSI Standard 1 1 15 described at the end of Table 3 3 Table 3 3 also summarizes the Distortion Analyzer s HP IB capabilities in terms of the twelve bus messages in the left hand column 3 14 Remote Mode Remote Capability In remote most of the Distortion Analyzer s front panel controls are disabled excep tions are the LCL key and the Clear Key Function S Shift AVG RMS However front panel displays and the signal at various outputs remain active and valid In remote the Distortion Analyzer may be addressed to talk or listen When addressed to listen the Distortion Analyzer will respond to the Data Trigger Clear SDC
148. irst time No instrument settings are changed by the transition from local to remote but the Trigger mode is set to Free Run code TO When actually in remote the Distortion Analyzer lights its front panel REMOTE annunciator When the Distortion Analyzer is being addressed whether in remote or local its front panel ADDRESSED annunciator turns on 3 23 Receiving the Local Message The Local message is the means by which the control ler sends the Go To Local GTL bus command If addressed to listen the Distortion Analyzer returns to front panel control when it receives the Local message If the instrument was in local lockout when the Local message was received front panel control is returned but lockout is not cleared Unless it re ceives the Clear Lockout Set Local message the Distortion Analyzer will return to local lockout the next time it goes to remote No instrument settings are changed by the transition from remote to local but all measurements are made in a free run mode When the Distortion Analyzer goes to local mode the front panel REMOTE annunciator turns off However when the Distortion Analyzer is being ad dressed whether in remote or local its front panel ADDRESSED annunciator lights If the Distortion Analyzer is not in local lockout mode pressing the front panel LCL local key might interrupt a Data message being sent to the instrument leaving the instrument in a state unknown to the controller This
149. ital display to 0 5 dB to reduce digit flicker for SINAD ratios less than 25 dB Related Detector Selection Sections Special Functions 3 79 Operation Description 3 80 Model 8903E Special Functions General Information Special Functions extend user control of the instrument beyond that normally available from dedicated front panel keys They are intended for the user who has an understanding of the instrument and the service technician who needs arbitrary control of the instrument functions Special Functions are accessed via HP IB entry of the appropriate numeric code refer to Procedures below The codes comprise a prefix decimal and suffix Special Functions are disabled by a variety of means depending upon the function Refer to the comprehensive listings below for actions which clear or disable any Special Function Special Functions are grouped by their prefixes into three categories as follows Prefix 0 This is the Direct Control Special Function and is intended for use in servicing the Distortion Analyzer All instrument error messages and safeguards are inactive This is discussed in detail in Section 8 If the Direct Control is entered inadvert ently enter Automatic Operation AU over the HP IB Prefixes 1 to 39 These are the User Special Functions which are used during normal instrument operation when a special configuration a special measurement or special informa tion is required All error messages
150. k on standard instruments those without Option 001 do not apply more than 42V peak to the outer conductor of the BNC INPUT connector when the FLOAT switch is the FLOAT position CAUTION Do not apply more than 300 Vrms either differential common mode or a combination to the INPUT connector s Common mode signal limitations exist because the instrument s ranging detector which determines the input voltage range is designed to read only the differential signal between the High and Low Inputs Thus the instrument can set an incorrect input range if a large common mode signal is present Erroneous measurements may be obtained as a result The Analyzer Input Block Diagram illustrates that the ranging detector senses the voltage difference between the High and Low Input lines Common mode signals are ignored by the ranging detector while the differential signals are measured The block diagram also illustrates that the High and Low Input lines have over voltage protection circuits that open when the input voltage single or combined common mode and differential exceeds the maximum safe limit OVEAR VOL TAGE PROTECTION HIGH INPUT DIFFERENTIAL TO ATTENUATOR SINGLE ENDED CONVERTER TO PROGRAMMABLE GAIN AMPLIFIER OVER VOLTAGE RANGING PROTECTION DETECTOR LOW INPUT ATTENUATOR Analyzer Input Block Diagram a Model 8903E Operation Common Mode cont d Example If a common mode signal o
151. l Information Table 1 2 are not warranted specifications but are typical char acteristics included as additional information for the user 1 3 SAFETY CONSIDERATIONS This product is a Safety Class I instrument that is provided with a protective earth terminal The Distortion Analyzer and all related documentation must be reviewed for familiarization with safety mark ings and instructions before operation Refer to the Safety Considerations page found at the beginning of this manual for a summary of the safety informa tion Safety information pertinent to the task at hand installation performance testing adjustment or service is found throughout the manual 1 4 INSTRUMENTS COVERED BY MANUAL Serial Numbers This instrument has a two part ser ial number in the form 0000A00000 which is stamped on the serial number plate attached to the rear of the instrument The first four digits and the letter constitute the serial number prefix and the last five digits form the suffix The prefix is the same for all identical instruments It changes only when a change is made to the instrument The suffix however is assigned sequentially and is different for each instru ment The contents of this manual apply directly to instruments having the same serial prefix es as listed under SERIAL NUMBERS on the title page 1 1 General Information Options Electrical Option 001 internal plug in filter options and various mechanical op
152. l level filtering or adding negative feedback According to Fourier mathematics the non linear terms in the circuit s transfer function give rise to harmonics of the signal Total harmonic distortion THD is usually defined as the ratio of the rms sum of the harmonics to the rms level of the fundamental The ratio is usually converted to or dB n oscilloscope gives only a rough indication of the amount of distortion present on a signal general rule of thumb is that if the non linearity causing the distortion is gentle for example not clipped a trained eye can discern distortion as low a 5 on an oscilloscope display Figure 1 4 shows several ex amples of waveforms with 5 THD and the compo nents that combined to produce them 596 distortion would be considered quite high in a quality hi fi amplifier audio spectrum analyzer which allows the user to see the magnitude of all harmonics is perhaps the best instrument to measure harmonic distortion The audio spectrum analyzer method however requires a fairly expensive instrument and some mathematical manipulation The traditional method of measuring distortion ac cepted by the Institute of High Fidelity and others is with a distortion analyzer The method is simple and adequate for most situations With a distortion analyzer you simply measure the signal level and set it up as a reference then you insert a notch filter tuned to the frequency of the fu
153. l line REN false If it is not in Local Lockout mode the Distortion Analyzer switches to local from remote whenever its front panel LCL key is pressed 3 16 Addressing The Distortion Analyzer interprets the byte on the bus eight data lines as an address or a bus command if the bus is in the command mode attention control line AT N true and interface clear control line IFC false Whenever the Distortion Analyzer is being ad dressed whether in local or remote the AD DRESSED annunciator on the front panel will turn on The Distortion Analyzer talk and listen addresses are switch selectable as described under paragraph 2 7 in Section 2 Refer to Table 2 1 for a comprehensive listing of all valid HP IB address codes To determine the present address setting refer to the discussion titled HP IB Address in the Detailed Operating In structions near the end of this section 3 19 Operation Model 8903E Table 3 3 Message Reference Table 1 of 2 HP IB Message Applicable Response All Distortion Analyzer operations except the LINE and Yes FLOAT switch functions are bus programmable All measurement results special displays and error outputs except the display are available to the bus Clear Yes DCL DC1 SDC the 22 2 state Responds equally to Device Clear DCL and Selected Device Clear SDC bus commands Remote Yes Remote mode is enabled when the REN bus control line is RL1 true However remote m
154. l modes the Distortion Analyzer automatically tunes the notch filter to the input frequency By means of keyboard entry using the NOTCH key the notch filter can be held to the current notch filter frequency setting To freeze the notch filter press the NOTCH TUNE key To return to the automatic tuning mode press the NOTCH TUNE key again or enter the HP IB program code 0 or 6 0SP Program Code Notch Tune x Automatic Notch Tuning 6 0SP or NO Hold Notch Tuning 6 1SP or N1 To freeze the notch filter press NOTCH TUNE LOCAL Notch Tune keystrokes ej m i 6 1SP program codes Function Function The above procedure gives the HP IB codes NO and 1 for the Notch Tuning function Notch Tuning may also be controlled over HP IB with Special Functions 6 0 and 6 1 When the NOTCH TUNE key is pressed the LED within the NOTCH TUNE key will light indicating the notch filter is on Pressing the NOTCH TUNE key again will turn off the key light indicating the notch filter is off When either HP IB program code 6 0SP or 6 1SP is entered the program code will flash on the left display The display blanks then shows the input signal frequency For HP IB program code 6 1SP the light within the NOTCH TUNE key will turn on The light will turn off for HP IB program code 6 08P When the HP IB program codes NO or N1 are used there is no numeric code shown in the left display When the Distortion Analyzer first powers up or w
155. lect the average responding detector Set the audio oscillator s level to 3V 5 14 Model 8903 Adjustments ADJUSTMENTS Fm BN EN a Rac NNN aN Sl 10 Adjust A4R93 AVG SCALE for a reading on the right display of the Distortion Analyzer that is the same as the reading on the ac voltmeter within 1 mV See Service Sheet 6 11 Set the audio oscillator s level to 150 mV On the Distortion Analyzer adjust 4 149 AVG OFFSET for a reading on the right display that is the same as the reading on the ac voltmeter within 0 5 mV See Service Sheet 6 12 Set AMPTD to 3V Repeat steps 10 through 2 until the right display of the Distortion Analyzer and the ac voltmeter are the same within the limits stated in steps 10 and 11 for both and 150 mV 5 15 Adjustments Model 8903E ADJUSTMENTS 5 14 VOLTMETER ADJUSTMENT NOT REQUIRING AN HP IB CONTROLLER Reference Service Sheets 6 and 7 Description The Distortion Analyzer is set to measure the ac level of an external audio oscillator The ac signal at the oscillator s output is monitored by an external ac voltmeter The ac to dc converter is adjusted so that its dc output agrees with the level measured by the external ac voltmeter at two different levels Both the rms responding and average responding ac to dc converters are calibrated The internal ac to dc converter produces a dc voltage that is read by the internal dc voltmeter and monitored by an extern
156. ll LEDs should light for approximately three seconds 2 After the turn on sequence the left display should show 0 000 kHz and the right display should show a low flickering value in mV In addition the measurement cycle annunciator in the upper left hand corner of the right display should be blinking and the AC LEVEL and LOW PASS 80 kHz keys should light 3 Connect the audio oscillator output to the INPUT of the Distortion Analyzer with a BNC to BNC cable Set the FLOAT switch to the ground position See Figure 3 3 4 Connect the oscilloscope to the MONITOR output See Figure 3 3 5 Set the audio oscillator to 1 Vrms at 1 kHz The left display should show the frequency of the audio oscillator at approximately 1 kHz The right display should show the amplitude of the audio oscillator at approximately 1V The oscilloscope should show a 1kHz 1 ms period sine wave of approximately 7 Vpp 6 Press the RATIO key The RATIO light should light The right display should show 100 NOTE In this and the following steps the displays may vary a few least significant digits 7 Press the AVG RMS key The AVG RMS key should light The right display should remain at approximately 100 3 8 Model 8903E Operation OPERATOR S CHECKS Press the AVG RMS key The AVG RMS key should light Set the FLOAT switch to FLOAT The right display should remain at approximately 100 Set the FLOAT switch back to ground Press the LOG
157. llator or analyzer can be substituted to determine which instrument is at fault EQUIPMENT Audio HP 339A or HP 8903B PROCEDURE 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground Connect the output of the audio oscillator to the Distortion Analyzer s INPUT 2 On the Distortion Analyzer press DISTN Set the audio oscillator frequency and level open circuit and the Distortion Analyzer s LP FILTER as indicated below For each setting the right display should be within the limits indicated Audio Oscillator LOW Limits 96 Low Frequency Hz Level Fitter Actual Maximum 20 1 000 1 000 1 000 1 000 20 000 50 000 50 000 100 000 100 000 100 000 4 11 Performance Tests Model 8903E PERFORMANCE TESTS 4 9 DISTORTION AND SINAD ACCURACY PERFORMANCE TEST SPECIFICATION Characteristic Performance Limits DISTORTION Accuracy 20 Hz to 20 kHz 20 kHz to 100 kHz SINAD Accuracy 20 Hz to 20 kHz 20 kHz to 100 kHz DESCRIPTION A signal with a known distortion level is created artificially by summing the outputs from two audio oscillators at the input of the Distortion Analyzer The artifical distortion is then measured by the Distortion Analyzer To calibrate the distortion the second oscillator is set to a harmonic of the low distortion oscillator the two signals are set to a common reference
158. ly press the LOG LIN key again If the ac level is to be displayed relative to a reference refer to Ratio and LOG LIN To measure the ac level of a signal at the INPUT connector Measurement LOCAL M keystrokes LEVEL e lt gt T program codes Measurement M1 is the program code for AC LEVEL When ac level is selected the LED within the AC LEVEL key will light The right display shows the ac level with the appropriate units The Distortion Analyzer automatically ranges for maximum resolution and accuracy The left display shows the input signal frequency If the input level to the frequency counter is too small the left display will show 0 000 kHz This will often occur when the signal is in the stop band of the optional plug in HP BP filters but not the low pass filters In ac level the Distortion Analyzer acts as an ac voltmeter The Distortion Analyzer automatically sets the input attenuation and the gain settings of the various amplifiers so that the input signal amplitude lies within the range of the output detector The output 3 33 Operation Model 8903B AC Level cont d Measurement detector converts the ac level to a dc voltage which is then measured by the dc voltmeter Technique cont d Comments Related Sections 3 34 and after correction for input gain and attenuation displayed in appropriate units The frequency of the input signal is also measured and displayed COU
159. lyzer by send wrt 729 OUTPUT 729 ing a different address Check that both the Distortion Analyzer s REMOTE and ADDRESSED annunciators are off Remote and Local Messages and the LCL Key NOTE OPERATOR S RESPONSE OPERATOR S RESPONSE OPERATOR S RESPONSE 3 12 This check determines whether the Distortion Analyzer properly switches from local to remote control from remote to local control and whether the LCL key returns the instrument to local control This check assumes that the Distortion Analyzer is able to both handshake and recognize its own address Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON Description WPL _ O send the Remote message by setting Re rem 728 REMOTE 728 mote Enable REN true and addressing the Distortion Analyzer to listen Check that both the Distortion Analyzers REMOTE and ADDRESSED annunciators are on Send the Local message to the Distortion icl 728 LOCAL 728 Analyzer Check that the Distortion Analyzer s REMOTE annunciator is off but its ADDRESSED annunciator is on Send the Remote message to the Distortion rem 728 REMOTE 728 Analyzer Check that both the Distortion Analyzers REMOTE and ADDRESSED annunciators are on Press the LCL key on the Distortion Analyzer Check that the Distortion Analyzer s REMOTE annunciator is now off but that its ADDRESSED annunciator remains on 8903 Operation x
160. m 3 1 Hewlett Packard Interface Operatingg Characteristics 3 1 Bus HP IB 1 4 Turn On Procedure 3 1 Compatibility 1 4 Local Operation ette EX EE 3 1 Selecting the HP IB Address 1 4 Simplified Operation Fide en 3 2 Accessories Supplied 1 4 Panel Features 3 2 Electrical Equipment Available 1 4 Detailed Operating Instructions 3 2 HP IB Controllers 21 1 4 Supplemental Information 3 2 Pand Connection Remote Operation HP IB 3 2 Operators Checks 3 2 1 4 Base 3 9 HP IB Functional Checks 3 2 Retrofit Kit 1 6 Operator s Maintenance 3 2 Mechanical Equipment Operators Checks 3 8 Available POTERE 1 6 Basic Functional Checks 3 8 Chassis Slide Mount Kit 1 6 Preliminary Check 3 8 Chassis Tilt Slide Mount Kit 1 6 Piller Check antes 3 9 Recommended Test Equipment 1 6 Distortion esu dar eoa 3 10 Principles of Operation for SINAD Check
161. m the display in the following format DDDDDE NNCRLFE Bytes 11 and 12 CR LF carriage return line feed Bytes 9 and 10 Two digit exponent Byte 8 Sign of exponent or Byte 7 E exponent Bytes 2 6 DDDDD reading from display where Byte 6 corresponds to the least significant digit of the reading in the display Byte 1 Sign tor F Data is always output in fundamental units that is Hz dB or V Error messages and the voltage value in dc level mode are always read out regardless of the status of the Read Display to HP IB commands Special Functions 3 15 Operation Model 8903E Service Request Condition Special Function 22 Description The Distortion Analyzer will issue a Require Service message under various circumstances For example a Require Service message will always be issued if an HP IB code error occurs Using HP IB program codes the operator may enable one or more conditions to cause the Require Service message to be issued Whenever the enabled condition occurs it sets both the bit corresponding to the condition and bit 7 RQS bit in the Status Byte The bits set in the status byte and the Require Service message are not cleared unless the status byte is read by serial polling a Clear message is received and executed by the Distortion Analyzer or a Controller Reset or Controller Clear Service Special Function is performed The enabled Service Request conditions are always disabled again w
162. measurement it is replaced by Error 31 which causes the Require Service message to be sent e Instrument Error When any Error is being displayed by the Distortion Analyzer including HP IB Code error Error 24 3 28 Selecting the Service Request Condition Use Special Function 22 Service Request Condition to enable the Distortion Analyzer to issue the Require Service message on any of the conditions above ex cept HP IB code errors which always cause the Re quire Service message to be sent The Service Request Condition Special Function is entered from HP IB The conditions enabled by Special Function 22 are always disabled by the Clear message A description of the Service Request Condition Special Function and the procedure for enabling the various conditions are given under Service Request Condition in the Detailed Operation Instructions Normally device subroutines for the Distortion Analyzer can be implemented simply by triggering measurements then reading the output data In certain applications the controller must perform other tasks while control ling the Distortion Analyzer Figure 3 7 illustrates a flow chart for developing device subroutines using the instrument s ability to issue the Require Service message when data is ready This sub routine struc ture frees the controller to process other routines until the Distortion Analyzer is ready with data 3 29 Sending the Status Byte Message The Status Byte message co
163. ment AC Calibrator HP 745A or Datron 4200 or Fluke 5200A Dual Banana to BNC Adapter HP 10110B Dual Banana to BNC Adapter 1251 2277 8903E DISTORTION ANALYZER T T p Ps CALIBRATIOR Figure 5 2 High Input Flatness Adjustment Test Setup Procedure High Input Flatness Adjustment l Set the ac calibrator to 1 kHz at 4 Vrms 2 Connect the equipment as shown in Figure 5 2 3 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground Set LP FILTER off 4 The right display of the Distortion Analyzer should read between 3 9 and 4 1V Check that the input is on range 10 by pressing S Shift NOTCH TUNE S Shift NOTCH TUNE The first two digits of the left display should be 10 Press AC LEVEL Press RATIO 5 Set the ac calibrator frequency to 40 kHz Adjust A2C3 HIGH 12 DB for a reading on the right display between 99 70 and 100 3 8903 ADJUSTMENTS Adjustments 6 10 11 12 13 14 15 16 Set the ac calibrator frequency to 100 kHz Adjust A2C3 for a reading between 99 50 and 100 5 Repeat steps 5 and 6 as often as needed until the flatness at 40 kHz and 100 kHz is within the limits given NOTE If the flatness cannot be adjusted so that the 40 kHz and 100 kHz readings are both within the given limits change A2C4 as follows If the 100 kHz reading is higher than at 40 kHz
164. mote Address the Distortion Analyzer to listen wrt 728 M3 OUTPUT 728 M3 completing the Remote message then send a Data message selecting the Distortion measurement Check that both the Distortion Analyzers REMOTE and ADDRESSED annunciators are on Check also that its Distortion key light is on Local Lockout and Clear Lockout Set Local Messages NOTE This check determines whether or not the Distortion Analyzer properly receives the Local Lockout message disabling all front panel keys The check also determines whether or not the Clear Lockout Set Local message is properly received and executed by the Distortion Analyzer This check assumes that the Distortion Analyzer is able to handshake recognize its own address and properly make the remote local transitions Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON Operation lt gt ae ee rE nee nee Model 8903E OPERATOR S CHECKS OPERATOR S RESPONSE OPERATOR S RESPONSE Clear Message NOTE OPERATOR S RESPONSE OPERATOR S RESPONSE 3 14 send the first part of the Remote message enabling the Distortion Analyzer to remote REMOTE 7 Send the Local Lockout message LOCAL LOCKOUT 7 Address the Distortion Analyzer to listen completing the Remote message OUTPUT 728 Check that both the Distortion Analyzer s REMOTE and ADDRESSED annunciators are o
165. mote with local lockout to local When the Distortion Analyzer goes to local mode the front panel REMOTE annunciator turns off 3 26 Receiving the Pass Control Message The Distortion Analyzer does not respond to the Pass Control message because it cannot act as a controller 3 27 Sending the Require Service Message The Distortion Analyzer sends the Require Service message by setting the Service Request SRQ bus control line true T he instrument can send the Require Service message in either local or remote mode The Require Service message is cleared when a serial poll is executed by the controller or if a Clear message is received by the Distortion Analyzer During serial poll the Require Service message is cleared immedi ately before the Distortion Analyzer places the Status Byte message on the bus An HP IB code error will always cause a Require Service message to be issued In addition there are two other conditions which can be enabled to cause the Require Service message to be sent when they occur All three conditions are described as follows Model 8903 Data Ready When the Distortion Analyzer is ready to send any information except error codes or the Status Byte e HP IB Code Error When the Distortion Analyzer receives an invalid Data message This condition always causes a Require Service message to be sent NOTE The display indicates a transient condition After nine attempts to make a
166. n Press the Distortion Analyzer s LCL key Both its REMOTE and ADDRESSED annunciators should remain on Send the Clear Lockout Set Local message LOCAL 7 Check that the Distortion Analyzer s REMOTE annunciator is off but its ADDRESSED annunciator is on This check determines whether or not the Distortion Analyzer properly responds to the Clear message This check assumes that the Distortion Analyzer is able to handshake recognize its own address make the remote local changes and receive Data messages Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON Send the first part of the Remote message enabling the Distortion Analyzer to remote REMOTE 7 Address the Distortion Analyzer to listen wrt 728 M3 completing the Remote message then send a Data message that selects the Distortion measurement OUTPUT 728 M3 Check that both the Distortion Analyzers REMOTE and ADDRESSED annunciators are on and that the Distortion key light is also on Send the Clear message setting the RESET 728 Distortion Analyzer s measurement to AC LEVEL Check that both the Distortion Analyzer s REMOTE and ADDRESSED annunciators are on and that the AC LEVEL key light is on uu Model 8903E Operation x OPERATOR S CHECKS Abort Message NOTE This check determines whether or not the Distortion Analyzer becomes unaddressed when it receives the Abort message This check ass
167. n Analyzer is connected to the input At various frequencies the ac level of the output is measured with the audio filters in and out The ratio of the two levels is the frequency response of the filter at that frequency EQUIPMENT Audio Synthesizer HP 3336C Controller with 1 85B Opt 007 PROCEDURE NOTE The Distortion Analyzer s HP IB address is assumed to be 728 All HP IB commands are given in BASIC 1 Connect the HP IB controller to the Distortion Analyzer Key in and execute the following command OUTPUT 728 41 0SP LO to initialize the instrument and set the 80 kHz LOW PASS FILTER off 2 Set the Distortion Analyzer s INPUT switch to ground Connect the audio synthesizer to the Distortion Analyzer s INPUT Press the LCL key then set LOG LIN to LOG 3 Set the audio synthesizer s level to 2V into an open circuit and set its frequency as indicated below For each setting perform the following procedure a Set all filters off Set RATIO off b Set RATIO on Set in the filter as indicated below b Note the dB ratio If it is not between 3 01 and 2 99 dB increment or decrement the audio synthesizer s frequency slightly until the indicated level is correct The displayed frequency should be within the limits indicated 4 16 Model 8903 Performance Tests PERFORMANCE TESTS Initial SOURCE High Pass Frequency Limits Hz Frequency or Low
168. n Analyzer is placed in the 3 21 Operation lt gt Listen Only mode when the remote enable bus control line REN is set true The instrument then responds to all Data messages and the Trigger Clear and Local Lockout messages However it is inhibited from responding to the Local or Abort messages and from responding to a serial poll with the Status Byte message Listen Only mode is provided to allow the Distortion Analyzer to accept programming from devices other than controllers for example card readers Data Input Format The Data message string or program string consists of a series of ASCII codes Each code is typically equivalent to a front panel keystroke in local mode Thus for a given operation the program string syntax in remote mode is the same as the keystroke sequence in local mode Example 1 shows the general case programming order for selecting Distortion Analyzer functions Specific program order considerations are discussed in following paragraphs under Program Order Consider ations All functions can be programmed together as a continuous string as typified in Example 2 The string in Example 2 clears most Special Functions with Automatic Operation selects a distortion measurement with 30 kHz low pass filtering and log units then triggers a settled measurement Program Codes All of the valid HP IB codes for controlling Distortion Analyzer functions are summa rized in Table 3 6 All fr
169. n be displayed using HP IB program code 11 1 To use the RATIO key set the display to the desired reference value This can be done by adjusting the signal parameter being measured to a reference setting or by entering the numeric reference via the HP IB followed by HP IB code R1 The entry must be made in fundamental units for example for a ratio reference of 60 mV enter 06 regardless of the displayed value The display will show the measurement result relative to the reference value The units used with the right display depend upon the setting of the LOG LIN key see table above Pressing the LOG LIN key alternates the display between the LOG and the LIN functions When the measurement mode is changed the last setting of the LOG LIN key for that mode is remembered and applied to the new measurement To re enter ratio with the previous ratio reference or to read the reference enter in the corresponding HP IB program code The special function codes are listed as follows Ratio Operation ode Re enter ratio with the pre vious reference Read ratio reference If the display shows 100 mV to enter this value as the RATIO reference for future measurements 3 73 Operation Examples contd Program Codes indications Comments Related Sections 3 74 Model 8903 RATIO and LOG LIN cont d Special Function 11 LOCAL keystrokes x program codes x program codes The HP
170. n be mathematically determined If the signal is sinusoidal for example the rms value is the peak amplitude divided by v2 This measurement is greatly simplified with an rms voltmeter which electronically measures the rms level and displays the result However no other informa tion about the signal is provided The Distortion Analyzer contains both an rms and an average re sponding voltmeter The rms level of the signal is displayed whenever the AC Level mode is selected The average level can be displayed by pressing the AVG RMS key When the LED is lit the analyzer is in Average mode A special function is also pro vided which converts the measurement result into watts for a specified external load resistance access able only through HP IB Another important ac signal characteristic is the vari ation in level vs frequency flatness Of course you can easily set a reference level such as 1V at a particular frequency such as 1 kHz and monitor the change in level as the input frequency is changed The external source s level is assumed to be flat otherwise it too must be checked The Distortion Analyzer makes this measurement easier in two ways First the reference can be set to 100 or 0dB by the press of a button the RATIO key Second the results can be logged into a controller over HP IB to be plotted on a printer or plotter An additional parameter related to ac level is gain and more often gain vs freq
171. nd 99 80 on the right display Set the audio oscillator s frequency to 1 kHz The right display should read between 99 00 and 101 096 CCITT Weighting Filter Option 011 or 051 a Set HIGH PASS 400 Hz or weighting filter off if on Set the audio oscillator s frequency to 800 Hz Set RATIO off Set RATIO on b Press CCITT WEIGHTING Adjust A2ZAIR4 or A2A2R4 CCITT for a steady reading of 100 0 on the right display CCIR Weighting Filter Option 012 or 052 a Set HIGH PASS 400 Hz or weighting filter off if on Set the audio oscillator s frequency to 6300 Hz Set RATIO off Set RATIO on b Press CCIR WEIGHTING Adjust A2AIR7 A2A2R7 CCIR for a steady reading of 407 4 12 20 dB on the right display 5 10 Model 8903 Adjustments ADJUSTMENTS C Message Weighting Filter Option 013 or 053 a Set HIGH PASS 400 Hz or weighting filter off if on Set the audio oscillator s frequency to 1 kHz Set RATIO Set RATIO on b Press C MESSAGE WEIGHTING Adjust AZAIR6 or A2A2R6 CMSG for a steady read ing of 100 0 on the right display CCIR ARM Weighting Filter Option 014 or 054 a Set HIGH PASS 400 Hz or weighting filter off if on Set the audio oscillator s frequency to 6300 Hz Set RATIO off Set RATIO on b Press CCIR ARM WEIGHTING Adjust A2AIR7 or A2A2R7 CCIR for a steady reading of 213 8 6 6 dB on the right display A Weighting Filter Option 015 or 055 a Set HIGH PASS 400 Hz
172. nd typically indicates a transitory state in instrument operation After nine successive occurrences the display changes to Error 31 Error 31 is output to the HP IB using the HP IB format shown above The table below describes all Operating and Entry errors The error code message and the action typically required to remove the error causing condition is given Additional information pertaining to particular errors is also given Error Code Action Required Comments Operating Errors Reading too large for This error code indicates that although the required display calculation is within the capability of the instrument the result of the calculation exceeds the display capabilities Calculated value out of Enter new RATIO reference Refer to RATIO and LOG LIN range Notch cannot tune to Adjust input frequency to within specified limits Refer input to Table 1 1 Input level exceeds This error code indicates that the input overload instrument specifications detector has tripped not in range hold This could be caused by too large an ac signal or too much ac ona signal NOTE Although error codes 17 and 19 are officially listed here under Operating Errors they should be considered rather as diagnostic indications Internal voltmeter cannot This error code indicates that the counter has failed to make measurement return a value This can only be caused by a malfunction in
173. ndamental and measure the output of the filter relative to the input This is the method used by the Distortion Analyzer in the DISTN mode where the tuning and measuring are done automatically When using the distortion analyzer method it is important to understand that the measurement result is not total harmonic distortion as defined above except under the condi tion that the distortion is not too excessive but that it does predominate over any other signal impurities Some examples will illustrate these restrictions Consider the case of excessive harmonic distortion Let us use the example of a signal with 10 actual total harmonic distortion in which all the distortion comes from the second harmonic The second har monic is then 20 dB below the fundamental as viewed 2The Institute of High Fidelity Inc Standard Methods Of Measurement For Audio Amplifiers The Institute of High Fidel ity Inc New York 1978 p 9 1 9 General Information on a spectrum analyzer When this signal is measured by a distortion analyzer an error results from the first part of the measurement measuring the input level because the input level is not quite the same as the level of the fundamental If the fundamental level were 1 Vrms the second harmonic level would be 0 1 Vrms one tenth of the fundamental The total input level measured with a true rms voltmeter is the rms sum of the two components namely Input 1 2 0 1 1 00
174. nel using S Shift LCL Factory set to 28 decimal General Operating Syntax Excluding Rapid Frequency Count modes Automatic Operation Measurement Filters Special Functions Log Lin Ratio Numeric Data Input Format Except in Rapid Source mode DDDDDEINN 5 Digit Signed Mantissa Exponent Magnitude leading decimal not allowed Exponent Sign Indicates Exponent Follows Output Formats Except in Rapid Frequency Count mode Data valid data output value always lt 4 X 10 and in fundamental units DDDDDEtNNCRLF Signed Mantissa Line Feed Indicates Exponent Follows Carriage Return Exponent Sign Exponent Magnitude Errors 900DDE 05CRLF Error Code Line Feed Carriage Return Return to Local Front panel LCL key if not locked out Manual Trigger Front panel S Shift AVG RMS the Clear Key Function keys initiate Trigger with Settling measurement NEAN 5 4 Status Byte L3 Ic uw 128 Service RQS Bit 0 always 0 always 0 always 0 always Request Require Condition Service The condition indicated in bits 1 and 3 must be enabled to cause a Service Request by Special Function 22 Service Request Condition 2 The RQS bit bit 7 is set true whenever an HP IB code error occurs or when any of the conditions of bits 1 and 3 are enabled and occur Bits set remain set until the Status Byte is cleared Complete HP IB Capability as descr
175. nput Level Range DC Level Monitor Special Functions 3 63 Operation Description Block Diagram Model 8903E Monitor The MONITOR output provides a means of monitoring the ac signal into the output rms detector The auto ranging MONITOR output level is normally a 0 3 to 3 Vrms signal which is proportional to the input signal In ac level and dc level the MONITOR output provides a scaled representation of the ac component of the input signal In SINAD distortion and distortion level the MONITOR output provides a scaled representation of the input signal with the fundamental removed The output is dc coupled with a 6000 output impedance and a BNC female connector The MONITOR output can be used to drive other test instruments such as an oscilloscope wave analyzer or spectrum analyzer for further analysis A simplified block diagram of the Distortion Analyzer measurement circuits illustrating the relationships between the MONITOR output and the other circuit blocks is shown below The MONITOR output block diagram illustrates the signal path from the INPUT to the MONITOR output The diagram is that of a programmable gain amplifier with a tunable notch filter In ac level and dc level the notch filter is bypassed In SINAD distortion and distortion level the notch filter is switched into the signal path removing the fundamental frequency INPUT STAGE GAIN gs POST NOTCH GAIN INPUT Comments 3 64
176. nserted in either the left most or right most key position according to the filter option number 3 51 Operation Comments cont d 3 52 Model 8903E Filters cont d High Pass Bandpass Low Pass Left Most Key Position Right Most Key Position Filter Option Number Filter Option Number 400 Hz high pass CCITT weighting bandpass filter CCIR weighting bandpass filter C Message weighting bandpass filter CCIR ARM weighting bandpass filter A weighting bandpass filter The selected filters are always in the path of the audio signal With all filters off the 3 dB measurement bandwidth is approximately 10 Hz to 750 kHz The high pass or bandpass filters affect the signal being counted however the low pass filters do not Repeating the HP IB command to turn on a specific filter has no effect that is the filters cannot be toggled on and off using the same HP IB command The individual filter characteristics are given in Table 1 1 Specifications and in Table 1 2 Supplemental Information The optional weighting bandpass plug in filter assemblies weights the frequency response of the Distortion Analyzer as shown in their respective curve plots Lu ae o ul a 400 Hz E X T Gs aL Li LT 1j 1 kHz 100 kHz FREQUENCY Hz CCITT and 400 Hz High Pass Filter Plot Model 8903 RESPONSE dB RESPONS
177. nsists of one 8 bit byte in which 3 of the bits are set according to the enabled conditions described above under Sending the Require Operation lt p gt Service Message If one or more of the three condi tions described above are both enabled and present all the bits corresponding to the conditions and also bit 7 the RQS bit will be set true and the Require Service message is sent If one of the above condi tions occurs but has not been enabled by Special Function 22 neither the bit corresponding to the condition nor the RQS bit will be set and the Require Service message will not be sent The bit pattern of the Status Byte is shown in the table labeled Status Byte on the following pages Once the Distortion Analyzer receives the serial poll enable bus command SPE it is no longer allowed to alter the Status Byte When addressed to talk following SPE the Distortion Analyzer sends the Status Byte message NOTE Since the Distortion Analyzer cannot alter the Status Byte while in serial poll mode it is not possible to continually request the Status Byte while waiting for a condition to cause a bit to be set After the Status Byte message has been sent it will be cleared if the Serial Poll Disable SPD bus com mand is received if the Abort message is received or if the Distortion Analyzer is unaddressed to talk Regardless of whether or not the Status Byte message has been sent the Status Byte and any R
178. nt mode HP IB codes 8 1SP and 8 3SP perform the same function HP IB code 8 2SP can be entered over the bus but is ignored The error messages can also be selectively disabled to prevent unwanted error interrupts to the HP IB bus controller Error messages are one means by which the instrument safeguards accurate measurements When these safeguards are disabled erroneous measurements can result under certain condi tions This should be kept in mind when operating the instrument with error messages disabled Automatic Operation Error Message Summary Special Functions 3 47 Operation Description HP IB Output Format Error Displays 3 48 Model 8903E Error Message Summary The instrument generates error messages to indicate operating problems incorrect HP IB entries or service related problems The error message is generally cleared when the error condition is removed Error 31 is an exception The Error Messages are grouped by error code as follows Error 10 through Error 39 and Error 90 through Error 99 These are Operating and Entry Errors that indicate that not all conditions have been met to assure a calibrated measurement or that an invalid HP IB code sequence entry has been made The Error Disable Special Function 8 N can be used to selectively disable certain operating error messages Entry Errors require that a new program code entry be made Error 65 through Error 89 These are Service Errors that pro
179. nted circuit board places it in its 1 position If the TON and LON switches are both set to 1 the Talk Only setting will override If the address switches and the TON switch are all set to 1 the Distortion Analyzer will output one byte the status byte each measurement cycle Setting all switches to 1 defeats HP IB operation Figure 2 3 The HP IB Address Switch Shown as Set by the Factory The Address Shown is 11100 in Binary with Both Talk Only and Listen Only Off f Reinstall the top cover by reversing the procedure in step c above g Connect the line Mains power cable to the Line Power Module and reconnect the HP IB cable to the HP IB connector h To confirm the setting refer to HP IB Address in the Detailed Operating Instructions in Section 3 of this manual 2 8 Interconnections Interconnection data for the Hewlett Packard Inter face Bus is provided in Figure 2 4 2 4 Model 8903E RED Tobie 2 1 Allowable HP IB Address Codes Talk Listen Address Address Char Char acter acter Address Switches 2 9 Mating Connectors Interface Connector The HP IB mating connector is shown in Figure 2 4 Note that two securing screws are metric Coaxial Connectors Coaxial mating connectors used with the Distortion Analyzer should be the 500 BNC male connectors 2 10 Operating Environment The operating environment should be within the following limitations 890
180. o range to include fundamentals up to 100 kHz Electronic instrumentation provides most of the tools for quantitative analysis of audio signals Thus if the signal is non electrical for example mechanical or acoustic it must be converted to an electrical signal by a transducer of some kind for example strain gauge or microphone before it can be analyzed Apart from attentive listening to a hi fi system the most intuitive way of analyzing an electrical signal in the audio range is visually with an oscilloscope Here you get a feeling for the signal s size loudness frequency pitch and shape timbre You can also determine if these parameters change with time or 1 8 OS a ee Model 8903E are stable and you can even make some quantitative measurements on it for example peak level dc offset period risetime etc Many times however the pa rameter sought does not lend itself to easy visual analysis Thus the Distortion Analyzer was designed It combines into one instrument a series of general and specialized instruments under microprocessor control that make it easy for you to obtain accurate quantitative measurements on audio signals of any general waveshape 1 31 AC Level Consider the very common measurement of a signal s ac rms level To make this measurement with an oscilloscope you must first decide the nature of the signal because from it the relationship of the peak level to the rms level ca
181. ode is not entered until the first time the Distortion Analyzer is addressed to listen The front panel REMOTE annunciator lights when the instrument is actually in the remote mode When entering remote mode no instrument settings or functions are changed but all front panel keys except LCL are disabled and entries in progress are cleared Related Commands Interface and Functions Controls If in remote and addressed to listen the Distortion Analyzer makes a settled measurement according to previ ously programmed setup It responds equally to bus com mand GET and program code T3 Trigger with Settling a Data message Sets MEASUREMENT to AC LEVEL with the 80 kHz LP FILTER on and sets the trigger mode to free run Resets many additional parameters as shown in Table 3 5 Clears Status Byte RQS bit Require Service message if issued and Local Lockout Sets the Service Request Condition to the front panel LCL key When entering local mode no in strument settings or functions are changed but entries in progress are cleared In local triggering is free run only The Distortion Analyzer returns to local mode front panel GTL RL1 control Responds equally to the GTL bus command and Local Lockout Disables all front panel keys including LCL Only the con LLO RL1 troller can return the Distortion Analyzer to local front panel control Clear Lockout Set Local The Distortion
182. of the HP IB interface HPL used the Distortion Analyzer s ADDRESSED annunciator may be either on or off The controller s display should read 0 00 HPL or 0 BASIC Send the Remote message rem 728 REMOTE 728 Place the Distortion Analyzer in serial poll rds 728 V STATUS 728 V mode and address it to talk causing it to send the Status Byte message Display the value of V dsp V PRINT V OPERATOR S Check that the Distortion Analyzers REMOTE annunciator is on Depending upon the RESPONSE vintage of the HP IB HPL interface used the Distortion Analyzer s ADDRESSED annunci ator may be either on or off The controller s display should read 0 00 HPL or 0 BASIC 3 16 8903 Operation x OPERATOR S CHECKS Require Service Message NOTE This check determines whether or not the Distortion Analyzer can issue the Require Service message set the SRQ bus control line true This check assumes that the Distortion Analyzer is able to handshake recognize its own address make the remote local changes and receive Data messages Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON then after the power up sequence is complete press the DISTN key Send the first part of the Remote message REMOTE 7 enabling the Distortion Analyzer to remote Address the Distortion Analyzer to listen wrt 728 722 4SP OUTPUT 728 22 4SP completing the Remote message then send
183. on Special Function 5 The Distortion Analyzer contains a wideband true rms or average responding voltmeter with high accuracy and sensitivity The Distortion Analyzer can be switched to have either a true rms or averaging detector response To select the AVG Detector press the AVG RMS key The key light will light to indicate average detection To select the RMS Detector press the AVG RMS key again The key light will extinguish indicating true rms detection Program Code Detector x rms or 5 0SP average A1 or 5 25 Code AO is the HP IB code for RMS Detector Al is the HP IB code for AVG Detector For fast or slow detection selection either rms or average enter the following HP IB codes 5 0SP for fast rms detection or 5 1SP for slow rms detection For average detection enter the following HP IB codes 5 2SP for fast average detection or 5 3SP for slow average detection When 5 0SP or 5 1SP is entered the light in the AVG RMS key will go out if it is on When 5 2SP or 5 3SP is entered the light in the AVG RMS key will light indicating average detection has been selected When measuring complex waveforms or noise a true rms detector will provide a more accurate rms measurement than an average responding detector which has been calibrated to indicate the rms value of a sine wave For a sine wave both the true rms and the average responding detectors give correct rms readings However when the signal is a com
184. onal plug in filters can be configured in any combination desired If there is no filter ordered for a position a jumper wire is loaded and a label marked 1 3 General Information No Filter is placed above the filter key on the front panel The following list includes the name and option numbers for each available filter 400 Hz High Pass Filter Option 010 050 CCITT Weighting Filter Option 011 051 CCIR Weighting Filter Option 012 052 C MESSAGE Weighting Filter Option 013 053 CCIR ARM Weighting Filter Option 014 054 A Weighting Filter Option 015 055 Specific information on each plug in filter option can be found in the Detailed Operating Instructions in Section 3 under Filters 1 13 Mechanical Options The following options may have been ordered and received with the Distortion Analyzer If they were not ordered with the original shipment and are now desired they can be ordered from the nearest Hewlett Packard office using the part number included in each of the following paragraphs The mechanical options are shown in Figure 1 2 Front Handle Kit Option 907 Ease of handling is increased with the front panel handles Order HP part number 5061 9689 Rack Flange Kit Option 908 The Distortion Analyzer can be solidly mounted to the instrument rack using the flange kit Order HP part number 5061 9677 Rack Fiange and Front Handie Combination Kit Option 909 This is not a front h
185. onnectors operating environment instrument mounting storage and shipment In addi tion this section also contains the procedure for set ting the internal HP IB talk and listen address switches 2 2 INITIAL INSPECTION To avoid hazardous electrical shock do not perform electrical tests when there are signs of shipping damage to any portion of the outer enclosure covers panels meters Inspect the shipping container for damage If the shipping container or cushioning material is damaged it should be kept until the contents of the shipment have been checked for completeness and the instru ment has been checked mechanically and electrically Procedures for checking electrical performance are given in Section 4 If the contents are incomplete if there is mechanical damage or defect or if the instrument does not pass the electrical performance test notify the nearest Hewlett Packard office If the shipping container is damaged or the cushioning ma terial shows signs of stress notify the carrier as well as the Hewlett Packard office Keep the shipping materials for the carrier s inspection 2 3 PREPARATION FOR USE 2 4 Power Requirements To avoid the possibility of hazardous elec trical shock do not operate this instrument at line voltages greater than 126 5 Vac with line frequencies greater than 66 Hz Leakage currents at these line settings may exceed 3 5 mA The Distortion Analyzer requires a power source of 10
186. ont panel keys except the LCL key have corresponding program codes Table 3 4 shows the Distortion Analyzer s response to various ASCII characters not used in its code set The characters in the upper table will be ignored EXAMPLE 1 General Program Syntax and Protocol Controller Talk Audio Analyzer Listen Model 8903E unless they appear between two characters of a program code The characters in the lower table if received by the Distortion Analyzer will always cause Error 24 invalid HP IB code to be displayed and a Require Service message to be generated The con troller recognizes the invalid code entry and clears the Require Service condition Thereafter the invalid code entry is ignored and subsequent valid entries are processed in normal fashion As a convenience all lower case alpha characters are treated as upper case In addition to the ignored codes given in Table 3 4 codes used in the HP 8903A and 8903B Audio Analyz ers but not common to the Distortion Analyzer are ignored They do not generate an error message For example the output code AP1VL which sets the audio analyzer s source to 1V will be ignored Table 3 4 Distortion Analyzer Response to Unused ASCII Codes when inserted between two characters of a program code Automatic Operation Measurement Filters Special Functions Log Lin Ratio Trigger Excluding Rapid Frequency Count Mode EXAMPLE 2 Typical P
187. ontains information required to install operate test adjust and service the Hewlett Packard Model 8903E Distortion Analyzer This manual docu ments options installed in the Distortion Analyzer such as rear panel connections and internal plug in filters This section of the manual describes the instruments documented by the manual and covers instrument description options accessories specifications and other basic information This section also contains principles of operation on a simplified block diagram level and basic information on audio measurements The other sections contain the following information Section 2 Installation provides information about initial inspection preparation for use including ad dress selection for remote operation and storage and shipment Section 3 Operation provides information about panel features and includes operating checks opera ting instructions for both local and remote operation and maintenance information Section 4 Performance Tests provides the informa tion required to check performance of the instrument against the critical specifications in Table 1 1 Section 5 Adjustments provides the information required to properly adjust the instrument Section 6 Replaceable Parts provides ordering in formation for all replaceable parts and assemblies Section 7 Instrument Changes provides instrument modification recommendations and procedures Section 8 Service
188. or weighting filter off if on Set the audio oscillator s frequency to 1 kHz Set RATIO off Set RATIO on b Press WEIGHTING Adjust 2 1 or A2A2R3 A WTD for a steady reading of 100 0 on the right display 4 Perform the Audio Filters Performance Test paragraph 4 11 Adjustments Model 8903E ADJUSTMENTS 5 12 NOTCH FILTER TUNE AND BALANCE ADJUSTMENT Reference Service Sheet 4 Description The Distortion Analyzer is set to measure the distortion from a clean audio oscillator The output from the notch filter is observed on an oscilloscope while the tuning and balance are adjusted for a minimum The measured distortion is also monitored on the amplitude display Equipment Audio HP 8903B or HP 339A Oscilloscope EL Se Sees HP 1740A OSCILLOSCOPE EXTERNAL TRIGGER AUDIO OSCILLATOR OUTPUT TEE Figure 5 5 Notch Filter Tune and Balance Adjustment Test Setup Procedure 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to FLOAT Set MEASUREMENT to DISTN Set LOG LIN to LOG 2 Set the audio oscillator to 2 8V at 1 kHz Connect the equipment as shown in Figure 5 5 3 Set the oscilloscope to view the ac signal at the MONITOR output Set the oscilloscope s trigger to external 4 Adjust A3R62 TUNE OFFSET and A3R63 BAL OFFSET for minimum signal and noise on the oscilloscope display
189. ow or vice versa enter the corresponding HP IB program code Post Notch Program Code Detector Response Fast RMS Detector Slow RMS Detector Fast AVG Detector Slow AVG Detector To enter a slow rms detector response mode x 5 1SP program codes Code Function For HP IB codes refer to the Procedure above As the HP IB program code is entered it will flash on the left display with the display returning to show the input signal frequency When HP IB program code 5 2SP or 5 35 is entered the LED within the AVG RMS key will light if not already on If the light is already on it will remain on When HP IB program code 5 0SP or 5 1SP is entered the LED within the AVG RMS key will turn off if not already off When the Distortion Analyzer is first turned on or when Automatic Operation is selected the fast rms detector is selected In SINAD additional low pass filtering is always used Fast detection either rms or avg cannot be selected by means of HP IB entry when in SINAD Slow detection can be used when in SINAD Automatic Operation Special Functions oO O D LLL 8903E Operation Post Notch Gain Special Function 3 Description The overall stage gain of the post notch circuit can be manually set by HP IB program code entry The gain is selectable from 0 dB to 60 dB in 20 dB steps In automatic operation mode the instrument will automatically select the optimum post notch gain
190. plex waveform or when significant noise is present the average responding detector reading can be in error The amount of error depends upon the particular signal being measured For noise an average responding detector reads low Many ac voltmeters employ an average responding detector For those applications requiring the use of an average responding detector press the AVG RMS key for average detection AC Level Distortion Distortion Level SINAD 3 41 Operation Description Procedure Example Program Code Indications Comments Related Sections 3 42 Model 8903 Display Level in Watts Special Function 19 The measurement mode can be set to read the ac input power level in watts into a specified external load resistance by using Special Function 19 through HP IB The range of the selectable load resistance in ohms is an integer value from 1 to 999 To set the measurement to display the ac level in watts into a specified resistance enter the corresponding HP IB code Resistance 0 Program Code 8 19 0SP 1 999 19 NNNSP where NNN corresponds to the load resistance in ohms To set the right display to read INPUT signal level in watts into an external 16Q speaker x 19 16SP program codes Saja pa For HP IB codes refer to Procedure above The right display shows a four digit readout of the ac power in watts but no units are indicated All measurement LEDs go off The lo
191. pressing the S Shift and AVG RMS keys Each time this key sequence is entered the Distortion Analyzer performs one Trigger with Settling Measurement cycle then waits for the data to be read Once the data is read out to the bus the instru ment returns to Hold mode If data is not read between trigger cycles it will be replaced with data acquired from subsequent measurements Special Considerations for Triggered Operation When in free run mode the Distortion Analyzer must pay attention to all universal bus commands for example serial poll enable SPE local lockout 110 etc In addition if it is addressed to listen it must pay attention to all addressed bus commands for example Go To Local GTL Group Execute Trigger GET etc As a consequence of this the Distortion Analyzer must interrupt the current measurement cycle to determine whether any action in response to these commands is necessary Since many elements of the measurements are transitory the measurement must be re initiated following each interruption Thus if much bus activity occurs while the Distortion Analyzer is trying to take a measurement that measurement may never be completed Trigger Immediate and Trigger with Settling provide a way to avoid this problem When the Trigger Imme diate T2 and Trigger with Settling T3 codes are received the Distortion Analyzer will not allow its measurement to be interrupted Indeed handshake 3 24 Model 8903E
192. quences 3 72 8903 Description Procedure Examples Operation RATIO and LOG LIN Special Function 11 The RATIO key can be used to compare any measurement except frequency and power to a reference value The reference value can be the result of a previous measurement The LOG LIN logarithmic linear key can be used to express the results in logarithmic or linear units The following table shows which units are applicable to the individual measurement modes Measurement RATIO On RATIO Off Mode LN toc LN AC LEVEL dBm into 6009 DC LEVEL dBm into 6000 SINAD dB DISTN dB DISTN LEVEL dBm into 6009 After initial power on switching measurement mode results in the configuration indicated by the asterisks In subsequent operations the last setting of the LOG LIN key is remembered for each measurement mode and applied to the new measurement When the RATIO LED is on the measurement result is compared to a reference value The reference value can be the result of a previous measurement The LOG LIN key allows any measurement result to be viewed in linear or logarithmic format The Distortion Analyzer stores only one ratio reference at a time When in ratio if a new measurement is selected ratio is disabled When returning to the previous measurement it is possible to re enter the ratio mode with the same factor as before using HP IB program code 11 0 Additionally the ratio reference ca
193. ration and Calibration Manual Agilent Technologies HP 8903E DISTORTION ANALYZER Including Option 001 SERIAL NUMBERS This manua applies directly to instruments with serial numbers prefixed 2507A and 2516A For additional important information about serial numbers see Instruments Covered by Manual in Section 1 First Edition HEWLETT PACKARD COMPANY 1985 EAST 24001 MISSION AVENUE TAF C 34 SPOKANE WASHINGTON U S A 99220 Operation and Calibration Manua Part No 08903 90053 Operation and Calibration Manua Microfiche Part No 90069 Printed JULY 1985 LA 1 Regulatory Information Updated March 1999 ig a c cx Regulatory Information Updated March 1999 Safety Considerations GENERAL This product and related documentation must be reviewed for familiarization with safety markings and instructions before operation This product has been designed and tested in accordance with IEC Publication 1010 Safety Requirements for Electronic Measuring Apparatus and has been supplied in a safe condition This instruction documentation contains information and warnings which must be followed by the user to ensure safe operation and to maintain the product in a safe condition SAFETY EARTH GROUND uninterruptible safety earth ground must be provided from the main power source to the product input wiring terminals power cord or supplied power cord set SAFETY SYMBOL
194. rogram String Controller Talk Audio Analyzer Listen AUM3L1LGT3 Automatic Operation ae S LL Trigger With Settling Distortion Log 30 kHz Low Pass Filter 3 22 Model 8903E Turning off Functions When operating in local mode the High Pass Bandpass optional plug in filters and Low Pass Filters and the Notch Tune the AVG RMS and Ratio functions toggle on and off with successive keystrokes In remote mode these func tions do not toggle on and off Instead each of the above groups has a specific code which turns off all the keys in the group The HP IB codes for turning off these functions are given in the table below HP IB Code Average off returns to RMS mode HP BP FILTERS all off HO LP FILTERS all off LO NOTCH HOLD off NO RATIO off RO Programming Numeric Data When entering ratio references to the Distortion Analyzer certain precau tions should be observed Numeric data may be entered in fixed floating point or exponential for mats Usually numeric data consists of a signed man tissa of up to five digits including leading zeros one decimal point and one or two digit signed expo nent The decimal point may fall between any two digits of the mantissa but should not appear ahead of the first digit If it does a leading zero will be automatically inserted by the Distortion Analyzer Any digit beyond the five allowed for the mantissa will be received as zero The general format for nu meric data
195. roperly set manual controls MEASUREMENT SINAD AC LEVEL cont d Detection true rms or rms calibrated average 3 dB Measurement Bandwidth gt 500 kHz Resolution 0 01 dB For ratios less than 25 dB Spe Mu Peu typical cial Function 16 0 will round the display to the s 93 5 nearest half dB to reduce digit flickering with noisy signals DC LEVEL Time to Return First Measurement lt 1 5s typical Tuning notch filter is tuned to counted input Measurement Rate 3 reading s frequency Time to Return First Measurement 1 5s typical FREQUENCY MEASUREMENT Measurement Rate 2 0 readings s typical Measurement Rate same as measurement mode DISTORTION erii NN 3 dB Measurement Bandwidth 10 Hz to 500 kHz pni xL C MU Detection true rms or rms calibrated average Displayed Resolution 0 000196 0 196 distortion 0 001 0 1 to 3 distortion 0 01 3 to 30 distortion 0 1 gt 30 distortion Time to Return First Measurement 1 5s typical Measurement Rate 2 readings s typical AUDIO FILTERS 400 Hz High Pass Filter Rejection gt 40 dB at 240 Hz gt 65 dB at 60 Hz Monitor Output Output Impedance 6000 In ac level mode provides scaled output of AC LEVEL measured input signal AC Converter true rms responding for signals with SINAD distortion and distortion level modes crest factor of lt 3 or rms calibrated average provides scaled output of input signal with the dete
196. rtion Ana Fuse 1 50A 250V time delay for 100 120 Vac lyzer to the Hewlett Packard Interface Bus for 0 75A 250V time delay for 220 240 Vac remote operations When in remote mode the front panel REMOTE annunciator lights Serial Number Plate First four numbers and Line Power Module permits operation from letter comprise the prefix that denotes the in 100 120 220 or 240 Vac The number visible strument configuration The last five digits form in window indicates nominal line voltage to the suffix that is unique to each instrument which instrument must be connected see Fig ure 2 1 Center conductor is safety earth ground Figure 3 2 Rear Panel Features 3 7 Operation Model 8903E OPERATOR S CHECKS 3 9 OPERATOR S CHECKS 3 10 Basic Functional Checks DESCRIPTION Using only an oscilloscope and an audio oscillator the overall operation of the Distortion Analyzer is verified OSCILLOSCOPE EQUIPMENT PROCEDURE 8903E DISTORTION ANALYZER VERTICAL NPUT OUTPUT gt c e MONITOR OSCILLATOR OUTPUT Figure 3 3 Basic Functional Checks Setup Audio Oscillator HP339A or HP 8903B OSCIIGSCODE Sareea weeded ei HP1740A Preliminary Check 1 Remove any cables from the Distortion Analyzer s INPUT Set the LINE switch to OFF and then back to ON and note that the front panel LED annunciators display segments and decimal points and key lights turn on A
197. s at turn on 3 17 Data Messages The Distortion Analyzer communicates on the inter face bus primarily with data messages Data messages consist of one or more bytes sent over the 8 data bus lines when the bus is in the data mode attention control line false Unless it is set to Talk Only the Distortion Analyzer receives data messages when addressed to listen Unless it is set to Listen Only the Distortion Analyzer sends data messages or the Status Byte message if enabled when ad dressed to talk Virtually instrument operations available in local mode may be performed in remote mode via data messages The only exceptions are changing the LINE switch and the FLOAT switch In addition the Distortion Analyzer may be triggered via data messages to make measurements at a particu lar time 3 18 Receiving the Data Message Depending on how the internal address switches are set the Distortion Analyzer can either talk only talk status only listen only or talk and listen both normal operation The instrument responds to Data mes sages when it is enabled to remote REN control line true and it is addressed to listen or set to Listen Only If not set to Listen Only the instrument re mains addressed to listen until it receives Abort message or until its talk address or a universal unlisten command is sent by the controller Listen Only If the internal LON Listen Only switch is set to 1 the Distortio
198. s check the Distortion Analyzer s ability to process or send all of the applicable HP IB messages described in Table 3 3 In addition the Distortion Analyzer s ability to recognize its HP IB address is checked and all of the bus data handshake and control lines except DIO8 the most significant data line which is not used by the Distortion Analyzer are set to both their true and false states These procedures do not check whether or not all Distortion Analyzer program codes are being properly interpreted and executed by the instrument however if the front panel operation is good the program codes in all likelihood will be correctly implemented The validity of these checks is based on the following assumptions e The Distortion Analyzer performs properly when operated via the front panel keys that is in local mode This can be verified with the Basic Functional Checks e The bus controller properly executes HP IB operations The bus controller s HP IB interface properly executes the HP IB operations If the Distortion Analyzer appears to fail any of these HP IB checks the validity of the above assumptions should be confirmed before attempting to service the instrument The select code of the controller s HP IB interface is assumed to be 7 The address of the Distortion Analyzer is assumed to be 28 its address as set at the factory This select code address combination that is 728 is not necessary for these checks to be valid
199. s the instrument in hold notch tuning mode Use 6 0 SP to re enter the automatic notch tuning mode Automatic Operation Special Functions Model 8903 Description Procedure Indications 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 wt es OOO c ccc Operation HP IB Address Special Function 21 The Distortion Analyzer s present HP IB address can be displayed by using the front panel S Shift LCL keys for the decimal display This display is of the form Addr in the left display NN in the right display where is the HP IB decimal address The address set at the factory is 28 11100 in binary The HP IB address can also be displayed using Special Function 21 Information on Special Function 21 is found in Comments below To display the HP IB address in decimal key in the S Shift LCL keys To display the HP IB address in decimal LOCAL keystrokes Assuming the same address the following will be displayed A list of the allowable addresses for the Distortion Analyzer is given below Talk Listen Decimal Talk Listen Address Switches Address Address Equiva Address Switches Address Address Equiva OO CO CO m w CO Cc Char Char lent Char Char acter acter acter acter O CO o B CO O O O CO gt OZ Zr 4
200. sitivity 5 mV per division minimum Input Impedance 1 MQ Triggering Internal and External Signature Analyzer Because the signatures documented are unique to a given signature analyzer type no substitution of types is recommended Test Oscillator Frequency 1 kHz Output 30 Vpp True RMS Voltmeter Type true rms responding Level Range 100 mV to 10V Frequency Range 20 Hz to 500 kHz Accuracy 0 296 of range 0 2 of reading Coupling ac 1 16 Model 8903E General Information Table 1 4 Service Accessories Accessory Specifications Suggested Model Digital Test No substitution recommended HP 08903 60018 Extender Board Extender Board 44 contacts 2 X 22 3 required HP 08901 60084 Extender Board 30 contacts 2 X 15 2 required HP 08901 60085 Foam Pad Conductive polyurethane foam 12 12 0 25 inches nonmagnetic HP 4208 0094 NOTE The performance tests adjustments and troubleshooting procedures are based on the assumption that the recommended test equipment is used Substituting alternate test equipment may require modification of some procedures Model 8903 Installation Section 2 INSTALLATION 2 1 INTRODUCTION This section provides the information needed to in stall the Distortion Analyzer Included is information pertinent to initial inspection power requirements line voltage and fuse selection power cables intercon nection mating c
201. ss otherwise noted no warm up period is required for these tests Line voltage must be within 5 and 10 of the specified input voltage 100 120 220 or 240 Vac if the performance tests are to be considered valid 4 2 EQUIPMENT REQUIRED Equipment required for the performance tests is listed in Table 1 3 Recommended Test Equipment in Section 1 of this manual Any equipment that satisfies the critical specifications in the table may be substituted for the recommended model s NOTE The performance tests are hased on the assumption that the recommended test equip ment is used Substituting alternate test equipment may require modification of some procedures 4 3 TEST RECORD Results of the performance tests may be tabulated on the Test Record shown in Table 4 1 at the end of the procedures The Test Record lists all of the tested specifications and their acceptable limits The results recorded at incoming inspection can be used for comparison in periodic maintenance and troubleshooting and after repairs or adjustments 4 4 CALIBRATION CYCLE This instrument requires periodic verification of performance Depending on the use and environmental con ditions the instrument should be checked using the following performance tests at least once every year 4 5 ABBREVIATED PERFORMANCE TESTING No abbreviation of performance testing is recommended Performance Tests Model 8903E PERFORMANCE TESTS 4 6 AC LEVEL ACCURACY PER
202. t another filter in the same group HP IB codes for the different filter keys shown below turn on the selected filter defeating others in the group if on To turn a high pass bandpass or low pass filter off via HP IB use code HO or LO respectively or select the alternate filter in the pair To select the left high pass or bandpass filter and the 30 kHz low pass filter y High Pass Filter Low Pass Filter LOCAL HIGH PASS LOW PASS keystrokes 400 Hz 30 kHz x H1L1 program codes High Pass F ilter Low Pass Filter Program Program High Pass Bandpass Filter Code Low Pass Filter Code Both off Both off 750 kHz low pass Left High Pass or Bandpass Filter Low Pass 30 kHz Right High Pass or Bandpass Filter Low Pass 80 kHz When a filter is activated by either automatic or manual selection the LED within that filter key will light Two plug in positions within the instrument permit the Distortion Analyzer to be configured with various high pass and band pass filter combinations The optiona plug in filter assem blies include a 400 Hz High Pass used to filter out 50 60 Hz hum and squelch signals and CCITT CCIR CCIR ARM Weighting and C Message Weighting Bandpass Filters These weighting bandpass filters are all psophometric in nature each filter characteristic approximates the response of human hearing according to separately established standards These optional plug in filter assemblies may be i
203. t error messages indicating invalid measurements due to incorrect gain settings are not generated unless overload conditions occur Automatic operation ensures accurate measurements for all combinations of input signals and measurement modes Automatic Operation DC Level Input Level Range Except DC Level Monitor Special Functions 3 61 Operation Description Procedure Example program codes Input Level Range Except DC Level Special Function 1 Input Level Range Program Code Full Scale x Automatic Selection 300V 189V 119V 75 4V 47 6V 30 0V 18 9V 11 9V 7 54V 4 76V 3 00V 1 89V 1 19V 0 754V 0 476V 0 300V 0 189V 0 119V 0 0754V To set the input level range to the 30 0V range Program Code For HB IB codes refer to Procedure above Indications 3 62 Model 8903E In all measurement modes the input level range can be set to a desired range by using Special Function 1 NN through HP IB The following discussion describes this function for function for all measurement modes except DC Level mode Refer to Input Level Range DC Level for additional information The input circuitry consists of a programmable attenuator and two programmable amplifiers In automatic operation mode the gain of the attenuator amplifier section of the input is automatically set according to the level of the To set the input level range to a selected range or to re enter the automatic selection mod
204. tch Detector Filtering except in SINAD Not Applicable Y Yes Except the LCL Keys The Clear Key Function 3 81 Operation Model 8903E Special Function Summary 2 of 3 Special Function 1 Diae x Description __ a AUTO OP CLEAR mens aM 98 Tune 6 0SP Automatic notch tuning Notch Tune 6 1SP Hold notch tuning Error Disable All errors enabled Error Disable 1 or Disable Analyzer errors Errors 12 17 31 and 96 Settings Hold input level ranges Hold Settings post notch gain decimal point and notch tuning at present settings N RATIO and LOG LIN Re enter Ratio 11 0SP Restore last RATIO reference and enter RATIO mode if allowed 11 1 11 1SP Display RATIO reference Mode Time Between 14 0 14 0SP Measurements Time Between Measurement Minimum time between measurements Add 1s between measurements 14 4 14 1SP SINAD Display 16 0 16 0SP Resolution 16 1 16 1SP Display Level 19 0 19 0SP Display level as watts in Watts into 8Q 19 NNN 19 NNNSP Display level as watts into NNNQ Read Display 20 0 20 0SP Read right display to 20 1 20 1SP Read left display HP IB Address 21 0 21 0SP 21 1 21 1SP SINAD 0 01 dB above 25 dB 0 5 dB below 25 dB 0 01 dB all ranges Watts Read Display to HP IB a Y Y Display Level in Y Y Displays HP IB address in binary in left display
205. tes a typical measurement setup using the Distortion Analyzer In the figure the system common line is connected to chassis or earth ground at two separate points the chassis of the Distortion Analyzer and the common point of the device under test Since two physically separate ground points are seldom at the same ground potential current will flow in the system common line Due to conductor resistance RC in the system common line the current causes a voltage drop This voltage drop a common mode voltage sums with the signal under measurement and can cause erroneous readings Grounding the system common line at a single point minimizes the effect of common mode voltages caused by ground loops Floating the Distortion Analyzer input circuitry isolates the outer conductor of the Distortion Analyzer from chassis ground Thus the Distortion Analyzer input circuits are grounded only through the device under test Note that the system common line is now grounded at a single point Model 8903 Hold Decimal Point Special Function 4 Description The position of the decimal point in the right display can be held in a specific location by using Special Function 4 Procedure To hold the decimal point in the right display to a specific position enter the corresponding HP IB program code Program Decimal Code Hold Position Automatic Selection DDDD V Range DDD D V Range DD DD V Range D DDD V Range 0 0000 V Ran
206. the ac calibrator frequency to 100 kHz Adjust A2C90 for a reading between 99 50 and 100 5 Repeat steps 22 and 23 as often as needed until the flatness at 40 kHz and 100 kHz is within the limits given NOTE If the flatness cannot be adjusted so that the 40 kHz and 100 kHz readings are both within the given limits change A2C89 as follows If the 100 kHz reading is higher than at 40 kHz decrease 2 89 by approximately 10 If the 40 kHz reading is higher than that at 100 kHz increase A2C89 by approximately 1090 On the Distortion Analyzer press RATIO to turn it off Set the ac calibrator frequency to 1 kHz and level to 15 Vrms The right display of the Distortion Analyzer should read between 14 7 and 15 3V Check that the input is on range 7 by pressing S Shift NOTCH TUNE S Shift NOTCH TUNE The first digit of the left display should be 7 Press AC LEVEL Press RATIO Set the ac calibrator frequency to 40 kHz Adjust A2C110 HIGH 24 DB for a reading on the right display between 99 70 and 100 3 5 6 8903 Adjustments ADJUSTMENTS 28 Set the ac calibrator frequency to 100 kHz Adjust A2C110 for a reading between 99 50 and 100 5 Repeat steps 27 and 28 as often as needed until the flatness at 40 kHz and 100 kHz is within the limits given NOTE If the flatness cannot be adjusted so that the 40 kHz and 100 kHz readings are both within the given limits change A2C102 as follows If the 100 kHz reading is
207. tions are docu mented in this manual The differences are noted under the appropriate paragraph such as Options in Section 1 the Replaceable Parts List and the sche matic diagrams 1 5 MANUAL CHANGES SUPPLEMENT An instrument manufactured after the printing of this manual may have a serial prefix that is not listed on the title page An unlisted serial prefix indicates that the instrument differs in some way from those documented in this manual A Manual Changes Supplement is shipped with this manual to provide you with the most current change information available at the time of shipment In addition to change information the supplement may contain information for correcting errors in the manual To keep this manual up to date and as accurate as possible Hewlett Packard recommends that you peri odically request the latest Manual Changes Supple ment The supplement is identified with the print date and part number that appears on the title page Complimentary copies of the supplement are available from Hewlett Packard 1 6 DESCRIPTION 1 7 General The HP Model 8903E Distortion Analyzer is an audio measurement system covering the frequency range of 20 Hz to 100 kHz The analyzer can perform distortion analysis frequency count ac level dc level and SINAD measurements The Distortion Analyzer reduces the number of instruments required in many applications involving audio signal characterization The Distortion Anal
208. tmeter to read ac volts On the Distortion Analyzer press the LCL key then set the MEASURE MENT mode to AC LEVEL Adjust A4R91 RMS SCALE for a reading on the right display of the of the Distortion Analyzer that is the same as the reading on the ac voltmeter within 1 mV See Service Sheet 6 Set the audio oscillator level to 150 mV On the Distortion Analyzer adjust A4R85 RMS OFFSET for a reading on the right display that is the same as the ac reading on the ac voltmeter within 0 5 mV See Service Sheet 6 If A4R85 does not have sufficient range add or alter A4R143 or A4R 144 as follows a Unsolder A4R143 or A4R144 if present b With a dc voltmeter measure the voltage at the junction of A4R72 and A4C46 c If the voltage ignoring polarity is greater than 2 mV compute R 1500 V where V is the voltage measured in volts d Select a resistor which has a standard value resistance nearest R If the measured voltage is negative solder the new resistor in the location for A4R143 if positive replace A4R 144 e After a five minute warm up measure the voltage again which should be between 2 and 2 mVdc f Repeat the adjustment of A4R85 Set the audio oscillator s level to 3V Repeat steps 6 through 8 until the right display of the Distortion Analyzer and the ac voltmeter readings are the same within the limits stated in steps 6 and 7 for both 3V and 150 mV On the Distortion Analyzer press AVG to se
209. to ground Set MEASUREMENT to DC LEVEL 2 Connect the 6000 feedthrough or a short circuit or a 500 load the INPUT 3 Adjust A2R44 OFFSET for a steady reading of 0 00V on the right display 5 9 Adjustments Model 8903E ADJUSTMENTS 5 11 400 HZ HIGH PASS AND WEIGHTING BANDPASS FILTERS ADJUSTMENT Reference Service Sheet 2 2A and 2B Description An audio oscillator is connected to the input of the Distortion Analyzer The oscillator is set to a specified frequency and a level reference is set The filter to be adjusted is then inserted and its gain is adjusted for a level equal to the reference Equipment Audio HP 8903B or HP 3336C Procedure NOTE In the following procedures the left most filter circuit board is designated 2 1 and the right most board A2A2 The board location corresponds to option series 010 and 050 respectively 1 Switch the Distortion Analyzer off then back on to initialize it Set the INPUT switch to ground 2 Set the audio oscillator amplitude to Vrms and connect its output to the Distortion Analyzer s INPUT 3 Perform the following steps for each filter installed 400 Hz High Pass Filter Option 010 or 050 Set the weighting filter off if on Set RATIO off Set the audio oscillator s frequency to 2 kHz Set RATIO on b Press HIGH PASS 400 Hz Adjust A2AIR6 or A2A2R6 400 HZ for a reading between 99 60 a
210. tru ment begin with the Simplified Operation and Opera tor s Checks Once familiar with the general operation of the instrument use the Detailed Operating Instruc tions for in depth and complete information on opera ting the Distortion Analyzer 3 1 Operation Simplified Operation Information on subsequent pages under Simplified Operation provides a quick introduction to front panel operation of the Distortion Analyzer It is designed to rapidly orient the novice user with basic procedures and therefore is not an exhaustive listing of all Distortion Analyzer functions However an index to the Detailed Opera ting Instructions appears in Table 3 2 to guide the operator to the more complete discussion of the topic of interest Panel Features Front panel controls indicators and connectors are illustrated and described in Figure 3 1 This figure describes the functions of the various key groups and summarize briefly how to use them Rear panel features are shown in Figure 3 2 Detailed Operating Instructions The Detailed Oper ating Instructions provide the complete operating reference for the Distortion Analyzer user The in structions are organized alphabetically by subtitle Not only do the instructions contain information on the various measurements that can be made listed under titles such as AC Level Distortion etc but there are also individual discussions of nearly all controls inputs and outputs for exampl
211. uency To make a gain measurement measure the input to the device then the output and take the ratio You first set an external source as desired then either measure it or set it as a reference press RATIO Then measure the output The result can be expressed in either or dB If desired an external source can be swept and the gain plotted as a function of frequency Mode 8903 1 32 Frequency Another common and basic measurement is frequency With an oscilloscope you simply determine the time interval between like points on the repetitive waveform and take the reciprocal With a frequency counter frequency is measured electronically and displayed The measurement is easier and usually much more accurate than could be made visually with an oscilloscope The Distortion Analyzer contains a counter which displays the frequency of the input signal for all ac measurements It should be noted that the counter is a reciprocal type it measures the period of the signal as you do with an oscilloscope and computes the reciprocal to obtain the frequency The advantage of this technique is that for low audio frequencies higher resolution is obtained in a shorter measurement time 1 33 DC Level Although not part of an audio signal dc level is a quantity often encountered in audio equipment for example bias voltages and outputs from ac to dc con verters Sometimes plots of dc level vs frequency are desired as
212. umes that the Distortion Analyzer is able to handshake recognize its own address make the remote local changes and enter serial poll mode Before beginning this check set the Distortion Analyzer s LINE switch to OFF then to ON HPL BASIC Send the Remote message to the Distortion rem 728 REMOTE 728 Analyzer OPERATOR S Check that both the Distortion Analyzer s REMOTE and ADDRESSED annunciators RESPONSE are on Send the Abort message unaddressing the cli 7 ABORTIO 7 Distortion Analyzer to listen OPERATOR S Check that the Distortion Analyzers ADDRESSED annunciator is off Note that the RESPONSE BASIC ABORTIO statement sends both the Abort message and the Local message Thus if HPL is being used the Distortion Analyzer s REMOTE annunciator should remain on If BASIC is being used the Distortion Analyzer s REMOTE annunciator should turn off Send the Local message HPL only The Local message was already sent with the ABORTIO 7 statement above Address the Distortion Analyzer to talk and 728 V ENTER 728 V store its output data in variable V OPERATOR S Check that the Distortion Analyzers REMOTE annunciator is off but that its AD RESPONSE DRESSED annunciator is on Send the Abort message unaddressing the cli 7 ABORTIO 7 Distortion Analyzer to talk OPERATOR S Check that both the Distortion Analyzer s REMOTE an ADDRESSED annunciators are RESPONSE off 3 15 Operation
213. unctions Model 8903E Description Procedure Example Program Code Indications HP IB Output Related Sections Operation Read Display to HP IB Special Function 20 The Distortion Analyzer can be set to read the information shown in either the left or right display to the HP IB bus Using Special Function 20 through HP IB allows the operator to manually determine which display s information will be placed on the HP IB bus This capability is typically used in the Talk Only Mode when logging data to a monitoring device Note that when set to Listen Only the Distortion Analyzer cannot place data on the bus If it is set to talk and listen both front panel control is relinquished and HP IB codes RR and RL determine the data output To set the Distortion Analyzer to output data to the HP IB from either the left or right display enter the corresponding HP IB program code Display Program Code Right 20 0SP or RR Left 20 1SP or RL To read the left display to the HP IB x 20 1SP RL program codes Code T ranenon For HP IB codes refer to the table in the Procedure above As the program code is entered both displays will blank the entered code will flash in the left display and four dashes will momentarily appear in the right display Both displays then return to the display that is appropriate for the current measurement mode The instrument outputs data fro
214. urement previously selected When any enabled condition occurs both the RQS bit and the bit corresponding to the enabled condition are set in the status byte and the SRQ control line on the HP IB will be set true The Distortion Analyzer s status byte is shown below for reference Distortion Analyzer s Status Byte Instru ment Error For more information on HP IB operation serial polling and the Status Byte message refer to the HP IB discussion titled HP IB Operation appearing earlier in Section 3 of this manual The HP IB Address Special Function provides a convenient means to determine at any time whether a Require Service message is being issued by the Distortion Analyzer HP IB Address HP IB Operation appears earlier in Section 3 3 77 Operation Description Procedure Example Program Code Indications 3 78 Model 8903 SINAD The Distortion Analyzer measures SINAD SIgnal to Noise And Distortion by first determin ing the following value signal noise and distortion noise and distortion S is then converted into the appropriate measurement units as follows units S X 100 dB units 20log S SINAD measurement can be made on signals from 20 Hz to 100 kHz and from 50 mV to 300V in the single ended mode FLOAT switch in grounded position SINAD measure ments are generally made to determine the sensitivity of a receiver In SINAD mode the Notch Filter tunes to the Counter Frequency
215. vel only 300V range Post Notch Gain 60 dB Range Hold Decimal Point DD DD mV range Post Notch Detection Filtering Fast RMS Detector Except in SINAD Notch Tune Hold notch tuning Error Disable Disable analyzer errors Program Code HP IB Codes for the special functions are summarized in the Special Function Summary above Indications Entering Special Functions As the HP IB program code is entered both displays will blank and the entered code will flash in the left display Four dashes will momentarily appear in the right display then are replaced with the appropriate reading for the selected measurement mode 3 84 Model 8903E Operation Special Functions Cont d Comments If a User Special Function prefixes 1 to 39 has a suffix of zero the zero need not be entered For example 5 0 SP equals 5 SP However 1 1 SP does not equal 1 10 SP If when entering an HP IB program code Error 21 invalid key sequence is displayed the special function requested has not been executed Entry of invalid special function suffixes results in display of Error 23 For additional information on Direct Control Special Functions prefix 0 or Service Special Functions prefixes 40 to 99 refer to Section 8 Related Automatic Operation Sections Default Conditions and Power up Sequence Special Function Summary table under Description above 3 85 Operation Description Procedure Example Program Codes Indications Related
216. vide additional service related information Service Errors must be enabled to appear and do not necessarily represent failures within the instrument Service Errors are discussed in the Service Section 8 of this manual The HP IB output format for errors is shown below 900DDE 05CRLF Fixed NES Line Feed Error Code Carriage Return Fixed Exponent For example Error 10 is output to the HP IB as 90010E 05CRLF This format differs from normal data outputs since normal data outputs will never exceed 4 X 109 Once an error has been input to the computing controller the error code is simply derived by subtracting 9 X 10 from the input number then dividing the result by 100 000 Shown below and on the next page are three types of error displays The first is typical of most error displays and is shown as a general case The second and third have specific meaning and occur often This display shows the general error display format These errors are output to the HP IB as shown under the HP IB format above This display means that no signal has been sensed at the input This display is output to the HP IB as Error 96 using the HP IB format shown above Model 8903 Error Displays cont d Error Messages Operation Error Message Summary cont d This display means that a signal has been detected but for various reasons a measurement result is not yet available This display is never output to the HP IB a
217. weight appropriately to determine the number of cycle counts Assign that value to variable Since the Distortion Analyzer uses a reciprocal counter the frequency of the input signal equals the number of input cycles r6 divided by total time elapsed during these input cycles The denominator is determined by counting the number of 2 MHz clock counts that occur during these input cycles and multiplying by the frequency of the clock 2 MHz Total time equals number of clock counts divided by 2 105 r5 Total time seconds 2 106 Thus r6 r6 Input frequency 2 e 2 106 15 2 106 rb Displays the frequency count result Terminates the program 3 71 Operation Model 8903E Rapid Frequency Count cont d Program Code Program Code RF is the HP IB code that initiates the Rapid Frequency Count mode indications When in Rapid Frequency Count mode the Distortion Analyzer s left display will show lt e a aes a Comments The major advantage of Rapid Frequency Count mode is that data can be taken in rapid sequence and stored in an array in the computing controller Then at a later time when operations do not require immediate controller attention the packed binary data can be converted into decimal frequency data This way the time required for the Distortion Analyzer to process the data into decimal frequency is eliminated This greatly increases its measurement speed for measuring tone burst se
218. wo successive measurements are processed and displayed For SINAD and distortion the ratio of the outputs of the Input and Output RMS Average Detectors is computed Input Frequency Measurement The signal from the last Programmable Gain Amplifier or the internal plug in HP BP Filters is conditioned by the Counter Input Schmitt Trigger to make it compatible with the Counter s input The period of the signal is then counted the count is processed by the Controller and the frequency is displayed on the left display 1 29 Controller The entire operation of the instrument is under con trol of a microprocessor based Controller The Con troller sets up the instrument at turn on interprets Keyboard entries executes changes in mode of opera tion continually monitors instrument operation sends measurement results and error messages to the front panel displays and interfaces with HP IB In addition its computing capability is used to simplify circuit operation For example it forms the last stage of the Counter converts measurement results into ratios in 96 ordB etc It also contains routines useful for servicing the instrument 1 30 BASICS OF AUDIO MEASUREMENTS The audio frequency range is usually taken to be from 20 Hz to 20 kHz Few people have hearing that good but the term is a convenient one to describe sub RF frequencies encountered in electronics The frequency range of the Distortion Analyzer extends beyond the audi
219. y Accurate distortion measurements typically can be made to less than 0 003 90 dB between 20 Hz and 20 kHz 1 8 Audio Testing The Distortion Analyzer has numerous features which make audio testing simple and convenient For example distortion results can be displayed in or dB AC level measurements can be displayed in volts dBm into 600Q or watts Measurement results can be displayed in or dB relative to a measured or entered value Finding the 3 dB points of filters and amplifiers is simplified by using the relative display feature The Distortion Analyzer also features high accuracy The internal Voltmeter flatness is bet ter than 0 5 0 05 dB over the range of 20 Hz to 20 kHz Residual Distortion is typically 0 003 90 dB over the same range See Figure 1 1 Balanced Input The Distortion Analyzer has a selec table balanced input configuration for testing bal anced devices For example in the quest for higher output power many audio amplifiers use bridged out put stages Such amplifiers can be difficult to charac terize because their outputs cannot be grounded test these devices the usual approach has been to use a balanced calibrated isolation transformer con nected to an analyzer with an unbalanced input The balanced input on the Distortion Analyzer make transformers unnecessary With the analyzer input in the float position connect the bridged device di rectly to the Distortion Analyzer to make
220. yzer is easy to use All measure ments are selected by one or two keystrokes For distortion measurements the Distortion Analyzer automatically ranges to and tunes to the input signal Measurement and output ranges are automatically selected for optimum resolution and accuracy The combined capabilities of the instrument are en hanced by microprocessor control resulting in more capability than would be available from separate instruments For example using the ratio key allows you to set a OdB or 100 reference for making frequency response measurements Microprocessor control allows flexible and versatile display formats 1 2 Model 8903E For example ac level can be displayed in V mV dBm into 6000 watts as a ratio in or dB referenced to an entered or measured value Virtually all functions are remotely programmable through the Hewlett Packard Interface Bus HP IB Programming is easy and straightforward All meas urements are made through a single input This elimi nates the need to switch between multiple inputs under remote control and reduces software development time and hardware costs The Distortion Analyzer measures the true rms level on all ac meas urements True rms measurements assure greater accuracy when measuring complex waveforms and noise For those applications where average detection is required the analyzer can be switched to average responding rms calibrated detection via a front panel ke

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