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User Manual DDS200 Digital Demodulation System 070-9952-00

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1. 2 7 Figure 2 7 MEASURE menu 2 10 Figure 2 8 RF nien 4 en e rv m Ue weal eoe A 2 10 Figure 2 9 RF 2 12 Figure 2 10 RF STO RF EDIT TEXT menu 2 15 Figure 2 11 PRESET Menu 2 16 Figure 2 12 PRESET menu 2 16 Figure 2 13 STORE menu 2 17 Figure 2 14 RECALL menu 2 18 Figure 2 15 Menu SETUP eee een nn nn 2 19 Figure 2 16 SETUP TIME DATE Menu 2 20 Figure 2 17 SETUP REMOTE menu 2 21 Figure 2 18 SETUP REMOTE IEC625 IEEEA88 menu 2 22 Figure 2 19 SETUP REMOTE RS232 menu 2 22 Figure 2220 SETUP PRINTER 2 23 Figure 2221 SETUP LEVEL UNITS menu 2 24 Figure 2 22 Mode menu 2 25 Figure 2223 INPUT menu 2 27 Figure 2 24 INPUT ATTENUATION menu 2 28 Figure 2 25 RF 2 29 Figure 2 26 STO EDIT TEXT menu 2 30 Figure 2 27 STATUS 2 31 Figure 2 28 STATUS SYMBOL RATE menu 2 32 Figure 2 29 SPECI
2. IEC IEEE 488 Connector Pin No BusLine PinNo Bus Line 1 DIO1 13 0105 2 0102 14 DIO6 12 11 10 9 8 7 6 5 4 3 DIO3 15 DIO7 i 4 0104 16 0108 hihi 6 5 EOI 17 REN SEN 6 DAV 18 GND 6 ZEN 24 23 22 21 20 19 18 17 16 15 M 13 iras 9 IFC 21 0 9 10 SRQ 22 GND 10 m ATN 23 12 Shield Logic GND DDS200 Digital Demodulation System User Manual Appendix B IEC IEEE Bus Interface Interface Functions Interface Messages Common Commands Devices controlled via IEC IEEE bus may be provided with different interface functions The interface functions of DDS200 are listed in Table B 2 Table B 2 Interface functions Control character Interface function 5 1 Source handshake AH1 Acceptor handshake L3 L4 LE3 LE4 Listener T5 T8 TE5 TE8 Talker capability to answer serial poll SR1 Service request 1 Parallel poll RL1 Remote local switchover DC1 Device clear DT1 Device trigger C1 C27 Controller function Interface messages are transmitted to the device on data lines with the attention line being active LOW They are used for communication between device and controller Common commands in the code range 10 to 1F hex They affect all devices on the bus without any addressing required Table B 3 Common commands QuickBASIC command IBCMD controller CHR 20 Command DCL Device Clear Function in the device Int
3. 4 4 Table 4 2 Conversion of displayed hexadecimal code into binary code sese e Oe Fos ee ew eS 4 4 Table A 1 Electrical Specifications eee A 1 Table A 2 Certifications and compliances 4 Table 3 Power Characteristics A 5 Table A 4 Environmental Characteristics A 5 Table A 5 Physical Characteristics A 5 Table B I B s Lines nr ER RR EE S B 2 Table B 2 Interface functions B 3 Table B 3 Common commands B 3 DDS200 Digital Demodulation System User Manual Table of Contents Table B 4 Addressed commands eee B 4 Table C 1 No erro Ve ox erem herr tnt hern mes Ree Si C 1 Table C22 Command errors C 1 Table 3 Execution errors C 4 Table C 4 Device specific _ C 8 Table C 5 Query errors C 8 Table D 1 Common Commands D 1 Table D 2 STATus Commands D 2 Table D 3 SYSTem Commands D 4 Table D 4 ROUTe Commands D 5 Table D 5 INPut Commands D 6 Table D 6 SENSe Command
4. MIH BER INTEGRATION SAMPLES Figure 2 29 SPECIAL FUNCTION menu EQUALIZER The operating mode of the channel equalizer is set with the EQUALIZER key 1 EQUALIZER MODE In the EQUALIZER MODE submenu the equalizer can be frozen FREEZE in the adaptive mode The equalizer can also be completely switched off OFF 2 CENTRAL TAP POSITION The equalizer is a complex 24 stage FIR filter giving 48 coefficients as a result of the real and the imaginary parts The processing of high order QAM signals places considerable demands on the equalizer capability Considering the mentioned length the type of equalizer used here is more complex than most other types For simulating a shorter equalizer the position of the central coefficient CENTRAL TAP my be set between 0 and 23 DDS200 Digital Demodulation System User Manual Manual Operation When selecting the position of the central tap the following should be considered m An equalizer with the central tap below 11 should be used for compen sating a signal subject to considerable post echoes for example caused by reflections In this case a maximum range is available for echo compensation However only in exceptional cases should the coefficient be set to a value below value below 2 is not useful at all W A signal generated under laboratory conditions should be measured with the central coefficient in position 11 or 12 Thus the equalizer can adapt symmetr
5. DDS200 Digital Demodulation System User Manual 2 45 Manual Operation MEASURE Menu The DDS200 has a measurement menu in which all main parameters are displayed To activate this menu press the MEASURE key in the MAIN FUNCTION block The menu shown in Figure 2 37 is displayed GOAN NEASURE SET RF RF LEVEL 330 000 HHz 66 7 dBuv C HSTELL DIAGRAM 66 7 dBuV E SE B rr d 3 SPECTRUM ECHO PATTERN SYMBOL RATE 6 300 MSPs ORDER OF GAM 64 PARA METERS ADD NOISE DFF Figure 2 37 MEASURE menu The LEVEL and BER parameters are shown In the upper section of the display These values are continually updated The level unit is configured in the SETUP LEVEL UNITS menu and automatically converted If applicable the following messages are displayed m FRAME UNSYNC m SYMBOL RATE UNSYNC m CARRIER RECOVERY UNSYNC m 1 Q INTERCHANGED m EQUALIZER UNLOCKED OFF FREEZE If none of the messages is displayed the corresponding synchronizations are in order 2 46 DDS200 Digital Demodulation System User Manual Manual Operation Table 2 2 provides more detailed information about the messages Table 2 2 Messages displayed in the MEASURE menu Message BER EXTERN SYMBOL RATE UNSYNC Meaning External BER measurement mode selected SPECIAL FUNCTION menu Symbol rate recovery not synchronized Possible sources The setsymbol rate is not correct STATUS menu
6. MPEG DATA OUTPUT The MPEG DATA OUTPUT key opens a submenu where the serial and parallel MPEG outputs can be configured with the following main parameters see Figure 2 30 QAH SPECIAL FUNCTION DATA OUTPUT SET RF RF LEVEL 330 000 HHz 66 7 dBu REED SOLOMON DECODER ERROR INDICATION BIT I MPEG FRAME 204 BYTES HORMAL INVERTED Figure 2 30 SPECIAL FUNCTION MPEG DATA OUTPUT menu REED SOLOMON DECODER This decoder forms the main part of the error protection in the MPEG 2 transport stream With a BER of 1E 4 in front of the decoder in the DDS200 the BER is always measured in front of the decoder a DDS200 Digital Demodulation System User Manual Manual Operation BER of 1E 11 is obtained after the decoder which corresponds to a practically error free transmission For demonstration purposes the error protection can be switched off In this case the uncorrected data are available at the MPEG output ERROR BIT IN MPEG FRAME With this key a selection can be made whether this software indication for a whole MPEG frame should be set or not in the event of uncorrectable data errors In practice this function is not very important since a connected decoder must evaluate the received data PARALLEL MPEG DATA PLL Here the integrated phase lock loop PLL eliminating the jitter in the data and clock lines can be switched on and off With certain symbol rates switching the PLL off may be advantageo
7. ESE 0 to 255 ESR IDN IST OPC OPC PRE 0 to 255 3 14 CLEAR STATUS sets the status byte STB the Standard Event Register ESR and the EVENt part of the QUEStion able and of the OPERation Register to zero The command has no effect on the mask and transition parts of the register The output buffer is cleared EVENT STATUS ENABLE sets the Event Status Enable Register to the defined value The query ESE returns the contents of the Event Status Enable Register in decimal form STANDARD EVENT STATUS QUERY returns the contents of the Event Status Register in decimal form 0 to 255 and then clears the register IDENTIFICATION QUERY for identification of the instrument The response is for example Rohde amp Schwarz EFA 0 2 00 0 the serial number not coded in the DDS200 2 00 z the firmware version INDIVIDUAL STATUS QUERY returns the contents of the IST flag in decimal form 01 1 The IST flag is the status bit sent during a Parallel Poll refer to ST Flag and Parallel Poll Enable Register PPE on page 3 24 OPERATION COMPLETE sets bit 0 in the Event Status Register if all preceding commands have been executed This bit may be used to assert a Service Request OPERATION COMPLETE QUERY places an ASCII character 1 into the output buffer as soon as all preceding commands have been executed PARALLEL POLL REGISTER ENABLE sets the Parallel Poll Enable Register to the defined value The qu
8. Output logic 0 active controller informs EFA via DTR that RS 232 interface is active DTR remains active as long as interface is switched for remote control Ground Interface ground connected to instrument ground Data set ready Input logic 0 active DSR not used in EFA Request to send Output logic 0 active EFA informs the controller via RTS that it is ready to accept data If RTS is active EFA is ready to receive a character Clear to send Input logic 0 active CTS controls the data output of EFA If CTS is active EFA is ready to output data To ensure error free and correct data transmission the parameters of the DDS200 and the controller must be set to the same values Setting is made in the SETUP REMOTE RS232 menu Parameters in bold type indicate the basic setting made at the factory Transmission rate baud rate Data bits Start bit Parity bit Stop bits The DDS200 has5 different baud rates 1200 2400 4800 9600 19200 Data are transmitted in 7 or 8 bit ASCII code The LSB least significant bit is the first bit transmitted Each data byte begins with a start bit The trailing edge of the start bit indicates the beginning of the data byte A parity bit can be transmitted for error correction There are three possibilities no even or odd parity In addition the parity bit can be set to logic 0 or logic 1 The transmission o
9. 95 i Replacing Fuses To replace the fuses perform the following procedure G9 1 Unplug the power cable 2 Turn the fuse holders counterclockwise with a screwdrive and remove the fuse holders and fuses Check the two fuses 3 4 Replace the defective fuse s with a fuse or fuses of the same type 5 Install the fuse holders and fuses using a screwdriver to lock into place 6 Plug in the power cable Fuses 1 2 IECI2T T3 15H 250V EMC Protective Measures To avoid impairment from electromagnetic interference the unit must be operated completely enclosed with all internal shielding covers fitted Suitably shielded signal and control cables are to be exclusively used Make sure that the control cables IEC IEEE bus or RS 232 are fastened to the rear panel with the locking screws since control cables with loose connections can cause the EMI limit values to be exceeded Similarly make sure that the control cables are properly connected at the PC end DDS200 Digital Demodulation System User Manual 1 11 Preparation for Use 1 12 Powering On Connect the unit to the AC supply refer to Connecting the Unit to the AC Supply on page 1 11 Switch on the power at the rear panel above the AC supply connector The yellow standby LED above the standby key lights up on the front panel Press
10. ACK cre ena SYSTem COMMunicate SERial PACE SYSTem PRINter FORMfeed Releases a from feed when the printer is connected SYSTem PRINter RESet Releases a reset when the printer is connected SYSTem PRINter EPSon HPLaserjet Adapts the printer interface to the SELect RSPud2 3 EPS HPL RSP Corresponding printer SYSTem PRINter 7 SELect SYSTem PRESet Sets instrumentto same status as obtained with PRESET key on front panel See page 2 16 SYSTem MODE QAM Selection of basic operating modes SYSTem MODE QAM QAM Demodulator ROUTe Subsystem Table D 4 ROUTe Commands Command Data Reply data Meaning ROUTe ISELect Input selection ROUTe ISELect RF IF DDS200 Digital Demodulation System User Manual D 5 Appendix D List of Commands INPut Subsystem Table D 5 INPut Commands Command Reply data Meaning INP ut ATTenuati ON OFF Automatic mode manual mode for AUTO _ ON OFF EA module in RF input INPutATTenuation ON normal automatic mode AUTO OFF manual mode INP ut ATTenuation LNOise LDIStortion Automatic mode for EA module in MODE LSDistortion IGN LNO LDIS 150 RF input INPutATTenuation i Bs eS MODE LNO Autom low noise LDIS Autom low Distortion LSD X Autom lowest distortion INP ut ATTenuation dd JB Entry of data for RF attenuator INP utATTenuation dd dB DEB E 5 dB INP ut GAIN ON OFF bzw 1 0 RF
11. CALL IBFIND DEV1 efa CALL IBPAD efa 6 CALL IBTMO efa 12 Includes driver Clears controller screen Opens channel to device Transfers device address to controller Sets response time to 3 s REM Example of SRQ initialization for messages CALL IBWRT efa CLS CALL IBWRT efa SRE 168 CALL IBWRT efa ESE 60 CALL IBWRT efa STAT OPER ENAB 32767 CALL IBWRT efa STAT OPER PTR 32767 CALL IBWRT efa STAT OPER NTR 32767 CALL IBWRT efa STAT QUES ENAB 32767 CALL IBWRT efa STAT QUES PTR 32767 GOSUB Srq PEN ON DO LOOP Resets Status Reporting System and clears output buffer Enables Service Request for STAT OPER STAT QUES and ESR Registers Sets Event Enable bit for Command Execution Device Dependent and Query Error Sets OPERation Enable bit for all events Sets associated bits of OPERation PTRansition and Ntransition Sets Questionable Enable bits for all events Sets associated bits of Questionable PTRansition Changes to Service Request Routine Endless loop REM Continues main program using endless loop The srq subroutine REM waits for an interrupt and in thi STOP S case starts automatically A Service Request is then processed in the Service Request Routine NOTE The variables and must be assigned meaningful values DDS200 Digital Demodulation System User Manual Ap
12. CARRIER RECOVERY UNSYNC Carrier recovery not synchronized The setfrequency is not correct or the jitter in the signal too high FRAME UNSYNC No MPEG sync word found The signal to be measured does not include an MPEG transport stream This is the case if the BER is too high See also I Q INVERSION on page 2 36 EXT BER measurement mode selected SPECIAL FUNCTION menu INTERCHANGED EQUALIZER UNLOCKED OFF FREEZE Recovery of MPEG transport stream Correct but data resulting from demapping were inverted Equalizer unable to adapt to channel If the QAM signal is converted to another frequency the spectrum is inverted if the conversion oscillator frequency is higher than the signal frequency The DDS200 identifies this inversion and automatically Corrects the decoded data information so that a valid MPEG data stream is available at the MPEG outputs See also Q INVERSION on page 2 36 OFF or FREEZE set equalizer to AUTO referto EQUALIZER MODE on page 2 34 UNSYNC Conditions atthe instrument input are so unstable that the equalizer cannot synchronize This happens in the case of considerable level variations or when the transmission path of the QAM channel has been changed If a hardware relevant error occurs the SELFTEST ERROR CODE is displayed in the bottom line of the MEASURE menu For evaluation of the SELFTEST ERROR CODE refer to Selftest QAM on page 4 3 Common to all ME
13. DATA 0 10 23 DATA VALID 11 24 PSYNC 12 25 GND 13 DDS200 Digital Demodulation System User Manual Manual Operation Transmission of 188 Transmission of 16 error data bytes rotection bytes m y gia p y Sj 360 0 03 0 5 DATA 0 to 7 UU LUI CLOCK PSYNC DATA VALID SY Sync Figure 2 64 Signals at parallel interface in 188 byte mode STATUS SER PAR MPEG FRAME SIZE Transmission of 188 Transmission of 16 error data bytes protection bytes gt lt gt 203 5 DATA 0 to 7 UUUUUUL CLOCK _ PSYNC DATA VALID SY Sync byte Figure 2 65 Signals at parallel interface in 204 byte mode STATUS SER PAR MPEG FRAME SIZE The serial MPEG 2 interface X7 uses asynchronous data transmission asynchronous serial interface ASI Asynchronous means that the data transmission rate is fixed irrespective of the data rate of the transmitted MPEG 2 signal To this end padding bits are inserted where no valid information is present With the serial MPEG 2 interface very long transmission links several hundred meters can be realized The switch SER PAR MPEG FRAME SIZE 188 204 bytes has the same function for the parallel and the serial interface in the 204 byte mode the error protection bits are transmitted in the 188 bytes mode padding bits are transmitted instead of the error protection bits DDS200 Digital Demodulation System User Manual 2 87 Manual Operation Th
14. This allows the display and setting of all the parameters of the current measurement function Special operating states are signalled via the LEDs on the front panel The display also indicates the allocation of soft keys depending on the menu selected With the cursor keys it is possible to modify text in the menus stepwise Figures entered via the numeric keypad are confirmed with the ENT key Press the ESC key to access the next higher menu level Settings are selected in the setting menus via the hard keys the soft keys and for variable parameters via the numeric keypad and the cursor keypad DDS200 Digital Demodulation System User Manual Manual Operation m The PRESET key enables the unit to be set to a defined default state All the parameters or sub ranges can be reset The firmware update can also be obtained with this key m The HARDCOPY key prints out of the display information m Keys STO and RCL are used to store and to recall reload device settings m The hard keys select the different menus which enable all the settings to be carried out The settings are displayed and set in the menus depending on the mode selected Display display indicates various test results test parameters and configuration settings depending on the menu selected The upper line always shows the title of the selected menu MEASURE Menu The MEASURE menu is divided into three parts see Fig ure 2 7 m The me
15. remote control reporting system 3 17 Status register description 3 23 diagram 3 22 queries 3 27 Status reporting system description 3 19 resetting 3 28 using 3 26 Storage temperatures 4 1 Store device settings 2 17 Structure command line 3 8 remote commands 3 5 Index 4 Subroutines examples E 1 Switchover to manual control programming E 2 Symbol rate 2 31 Syntax remote commands 3 5 SYSTem commands D 4 T Time Date menu 2 20 Troubleshooting 4 1 error messages 4 3 selftest 4 3 Two digital demodulating systems cascading 2 88 U UNIT commands D 11 V Vector error 2 74 limit values 2 75 DDS200 Digital Demodulation System User Manual
16. 3 The individual bits are independent of each other each hardware status is assigned a bit number which is the same for all five registers Bit 15 the most significant bit is set to zero in all registers Thus the contents of the registers can be processed by the controller as a positive integer cuore prese sess ieej gt PEPP sere T PTT amp amp to next higher register Ed 4 Summary bit ipse ELE amp logic AND logic OR of all bits Figure 3 3 Status Register Model DDS200 Digital Demodulation System User Manual 3 19 Remote Control 3 20 CONDition register The CONDition register is directly written to by the hardware or the summary bit of the next lower register Its contents reflects the current device status This register can be read but not written or cleared Reading the register does not change its contents PTRansition register The Positive TRansition register acts as a transition filter Upon transition of a bit of the CONDition register from 0 to 1 the associated PTR bit decides whether the EVENt bit will be set to 1 PTR bit 1 the EVENt bit is set PTR bit 0 the EVENt bit is not set This register can be written and read Reading the register does not change its contents NTRansition register The Negative TRansition register also acts as a transition filter Upon transition of a bit of the CONDition register from 1 to 0 the
17. 5 E 2 Service Request istnd sp Rute er den Len Rud lc S brew E 4 Appendix F Remote Control via RS 232 C Interface F 1 Setting the Transmission Parameters F 1 Displays in Remote Control F 1 Return to Manual Control 0 0 0 cece cee ere F 1 Characteristics of Interface F 2 Signalling Lines iic ee bes beg RR Ree Hue ERE qe rH DRE ES F 2 Transmission Parameters F 3 Interface Functions Jl sese rr me eet ete AUREIS F 4 Handshake ciei bee adhue Ive bag F 5 Software eee eens F 5 DDS200 Digital Demodulation System User Manual iii Table of Contents Index Local controller connection for Software Handshake F 6 Hardware Handshake F 6 Local Controller Connection for Hardware Handshake F 7 DDS200 Digital Demodulation System User Manual Table of Contents List of Figures Figure 2 1 Front panel controls 2 1 Figure 222 QAM MEASURE menu 2 3 Figure 2 3 MODE menu 2 4 Figure 2 4 INPUT menu 2 5 Figure 2 5 INPUT RECEIVER ATTENUATION menu 2 6 Figure 2 6 RF
18. 59 SYSTem TIME SYSTem DATE lt Year gt 1 to 12 1 to 31 Reply data 0 to 23 0 to 59 0 to 59 Meaning System time See page 2 20 System date SYSTem DATE Year 1 to 12 1 to 31 See page 2 20 SYSTem ER Ror Error No Error queries see Appendix C List Error description OLEHDr Messages device specific description SYSTem VER Sion YYYYN SCPI version Y year 1995 0 V z version SYSTem COMMunicate dd Modifies the set IEC IEEE address GPIB SELF ADDRess See page 2 20 SYSTem COMMunicate ddddd Sets the transfer rate for the serial SERial BAUD ddddd interface 1200 to 19200 SYSTem COMMunicate ace pagesesen SERial BAUD SYSTem COMMunicate d Sets the number of bits for the SERial BITS _ d serial interface 7 8 SYSTem COMMunicate seepage 6 20 SERial BITS SYSTem COMMunicate NONE EVEN ODD Sets the parity check for the srial SERial PARIty TY PE NONE EVEN ODD SYSTem COMMunicate pee page SERial PARity TY PE SYSTem COMMunicate d Sets the number of stop bits for the SERial SBITs 4 serial interface 1 2 SYSTem COMMunicate see pede ea SERial SBITs D 4 DDS200 Digital Demodulation System User Manual Appendix D List of Commands Table D 3 SYSTem Commands Cont Command Data Reply data Meaning SYSTemCOMMuniate NONE XON ACK Sets the handshake mode for the SERialPACE NONE XON
19. 64QAM is the default value BEEPER The internal acoustic signal generator can be configured in the BEEPER submenu With the different kinds of error that may occur the generator is active when the corresponding parameter has been set to EN ABLED or inactive when the corresponding parameter is set to DISABLED The following errors may be acoustically signaled 1 Recovery of symbol clock rate not synchronized Equalizer not synchronized Carrier recovery not synchronized Sync byte of MPEG frame not found At least one faulty byte in the 188 byte MPEG frame could not be corrected 2 Ue moo cs At least one faulty byte was corrected in the 188 byte MPEG frame DDS200 Digital Demodulation System User Manual 2 33 Manual Operation SPECIAL FUNCTION Menu 2 34 In the SPECIAL FUNCTION menu that is selected in the MAIN FUNCTION block special settings can be made for values that need not be changed in normal operation see Figure 2 29 In this menu the instrument can be set to a state where normal operation is not always guaranteed If a special function has been selected the yellow LED next to the key lights and turns off only after all functions have been reset to standard values In the menu default values are marked in bold refer to Preset Values and Menu Overview on page 2 58 Default values are selected in the following example BAN SPECIAL FUNCTION SET RF RF LEVEL 330 000 HHz 66 7 dBu EQUALIZER
20. Failure IF VAL Esr AND 64 gt 0 THEN PRINT User request IF VAL Esr AND 128 0 THEN PRINT Power on RETURN REM kkkkkkkkkkkkkkkkkkkkkkkkk Error routine kkkkkkkkkkkkkkkkkkkkkkk Fehlerbehandlung PRINT ERROR Outputs error message STOP Stops software REM ek kc e ee e eek ee e e e e e ee eee ee I e e e e e e e e A AG DDS200 Digital Demodulation System User Manual Pp ST EECU 9 Appendix F Remote Control via RS 232 C Interface Setting the Transmission Parameters To ensure error free and correct data transmission the parameters of the DDS200 Digital Demodulation System and the controller must be set to the same values They can be varied manually in the SETUP REMOTE RS232 menu Transmission parameters of the interface are factory set to the following configuration Baud rate 9600 bits 8 parity NONE stop bits 1 printout NONE Displays in Remote Control The remote control status can be seen by the LEDs REM and LLO in the STATE signal field In the REMOTE status all readouts appear on the screen Return to Manual Control Manual control can be selected again from the front panel or via the RS 232 interface Manual 1 Press key The LOCAL REMOTE menu appears 2 Press LOCAL softkey NOTE Command processing must be completed prior to the switchover as otherwise the device would be switched back immediately to remote control To prevent unintended switchover
21. GAM 64 PARA METERS SELFTEST ERROR CODE 000000 ADD HOISE DFF Figure 2 2 QAM MEASURE menu Selecting the Mode Using the main menu MODE hard key the MODE menu is entered After pressing the soft key on the right next to menu line Nyquist Demodulator FM Sound select the mode QAM Demodulator the parameters stored last in this mode are restored refer also to Mode Key Selecting the Mode on page 2 25 MAIN FUNCTION MODE MEASURE The selected mode is highlighted see Figure 2 3 DDS200 Digital Demodulation System User Manual 2 3 Manual Operation HODE RF CHRHHEL RF LEVEL STANDARD 46 250 MHz zZ 67 4 dBu B G F D x x 4 AAAS LPE PEER DET Figure 2 3 MODE menu Selecting the Input Using the main menu INPUT hard key the INPUT menu is entered Press the soft key on the right next to the menu line RECEIVER to select the RF input Depending on the unit configuration the connector used as input is indicated next to the RECEIVER soft key MAIN FUNCTION MODE MEASURE MODE TEASUBE INPUT SETUP SPECFUNC STATUS ALARM ALARM VL 2 4 DDS200 Digital Demodulation System User Manual Manual Operation In the example below the fron
22. Parameters page 2 82 Assignment and Functions of Parallel and Serial MPEG 2 Outputs page 2 85 Analog and Digital Cascading of Two Digital Demodulation Systems page 2 88 Application and Interpretation of Constellation Diagram In this subsection the basic causes of specific modulation errors are described with the aid of simulated constellation diagrams Using simulated data is instructive especially because it allows different effects to be demonstrated separately In the examples shown below the following basic settings were used A maximum possible DVB data transmission rate of 6 92 MSPS mega symbols per second or 41 73 Mbit s with 640AM Cosine roll off filtering with roll off factor r 2 0 15 PRBS pseudo random binary sequence data stream no coding In practice there is always a combination of various modulation errors that may be difficult to separate and identify To this end the DDS200 Digital Demodula tion System evaluates the measured constellation diagram using mathematical and statistical methods and furnishes a quantitative representation of results refer to Explanation of Calculated Parameters Formulas and Limit Values on page 2 68 All constellation diagrams shown are based on 64QAM modulation The effects of the modulation errors shown however apply to all other orders of QAM DDS200 Digital Demodulation System User Manual Manual Operation First a constellation diagram is shown representing a ve
23. ROLLoff R015 R020 R025 R030 See page 2 34 SENSe QAM ROLLoff SENSe QAM OR Der AUTO MANual Setting the QAM mode order MODE AUTO MAN See page 2 30 SENSe QAM OR Der MODE SENSe QAM ddd Setting the QAM order ORDer ddd 4 16 32 64 128 256 SENSe QAM settting the AUTO mode not ORDer use See page 2 30 SENSe QAM d ddd MSPS Setting the symbol rate that can be SY MBolrate VALue d ddd MSPS ion SENSe QAM 1 000 to 7 000 MSPS SY MBolrate VALue SENSe QAM d ddd MSPS Setting the upper limit of the SY MBolrate UPPer limit d ddd MSPS SENSe QAM i 1 000 to 7 000 MSPS SYMBolrate UPPer limit SENSe QAM d ddd MSPS Setting the lower limit of the symbol SY MBolrate LOWer limit d ddd MSPS SENSe QAM 1 000 to 7 000 MSPS SYMBolrate LO Wer limit see page SENSe QAM One time call at the conclusion of SYMBolrate AUTO STARt ON OFF the automatic symbol rate received SENSeQAM Within the UPPer LOWer limit SY MBolrate AUTO STAR Dataare sent without unit DDS200 Digital Demodulation System User Manual D 9 Appendix D List of Commands Table D 6 SENSe Commands Cont Command Data Reply data Meaning SENSe QAM Interrupt of the automatic symbol SY MBolrate AUTO S TOP 3 ee eee SENSe QAM 1 000 7 000 MSPS SY MBolrate AUTO STOP euge SENSe QAM HI MED LO Setting the QAM loop
24. Remote Control and in Appendix B IEC IEEE Bus Interface three core shielded cable with crossed transmit and receive lines is sufficient for remote control for updating the firmware a null modem cable is required DDS200 Digital Demodulation System User Manual Preparation for Use IEC IEEE Bus Connector The DDS200 can be connected to the IEC IEEE bus by means of connector X29 on the rear panel and remote controlled The bus address can be set in the setup menu refer to JIEC IEEE488 Menu Setting the IEC IEEE Bus Address on page 2 21 The set of remote control commands is described in Remote Control and in Appendix B IEC IEEE Bus Interface The interface meets the require ments of standards IEC 625 2 and IEEE 488 2 A shielded cable PK can be ordered as an accessory using the following part numbers Length m Order No 0 5 292 2013 05 1 292 2013 10 2 292 2013 20 4 292 2013 40 DDS200 Digital Demodulation System User Manual 1 17 Preparation for Use 1 18 DDS200 Digital Demodulation System User Manual Es c 0 84 Manual Operation This section provides information about the basic manual operation of the DDS200 Digital Demodulation System The section describes how to use the soft keys and hard keys to control the instrument The control elements of the DDS200 are arranged on the front panel in separate functional groups each in a different color for b
25. SELECTION F1 F2 IEC 127 T3 15 250 V 50 60 Hz CARR CLOCK eee X 9e GO AUDIO A 7 C AUDIO SERBUS Table 1 2 Legend for rear view Connectors 100 120 2 5A 220 240 1 3A AUTOMATIC VOLTAGE SELECTION F1 F2 IEC 127 T3 15 H 250 V 50 60 Hz Description AC supply connector VIDEO 750 Q750 OOO PILOT BLOWER X1 to X4 AC supply switch and fuses 100 V 120 V 1 127 3 15 H 250 V 50 Hz to 60 Hz 220 230 V 1 127 3 15 250 V 50 Hz to 60 Hz Automatic voltage selection Caution To prevent damage caused by overheating do not block the airflow of the blower Temperature regulated blower Internal temperature protection is provided in the unit if the blower failes If the temperature rises higher that 80 C the unit switches to standby operation These connector locations are for future use DDS200 Digital Demodulation System User Manual 1 5 Pr
26. amp 8 free amp amp 7 free amp amp 6 free amp _ amp 5 free amp 4 free amp 3 free amp 2 free amp 1 free amp 0 free PPE STATus QUEStionable register 1st flag response to parallel poll amp 7 Power on amp 6 User Request amp 5 Command Error amp 4 Execution Error amp 3 Device Dependent Error 6 2 Query Error amp logic AND amp 1l free amp 0 Operation Complete logic OR of all bits ESE ESR Error queue Output buffer Figure 3 4 Overview of status registers 3 22 DDS200 Digital Demodulation System User Manual Remote Control Description of Status Status Byte STB and Service Request Enable Registers SRE The STB is Registers already defined in IEEE 488 2 It provides a rough overview of the device status collecting information from the lower level registers It is comparable with the CONDition register of a SCPI defined register and is at the highest level of the SCPI hierarchy Its special feature is that bit 6 acts as the summary bit of all other bits of the Status Byte Register The Status Byte Register is read out by the query STB or a Serial Poll The SRE is associated with the STB The function of the SRE corresponds to that of the ENABle register of the SCPI registers Each bit of the STB is assigned a bit in the SRE Bit 6 of the SRE is ig
27. associated NTR bit decides whether the EVENt bit is set to 1 NTR bit 1 the EVENt bit is set NTR bit 0 the EVENt bit is not set This register can be written and read Reading the register does not change its contents With the aid of these two transition filter registers the user can define the status change of the CONDition register none 0 to 1 1 to 0 or both that is to be reported in the EVENt register EVENt register The EVENt register reports whether an event has occurred since its last reading it is the memory of the CONDition register It only registers events that have been reported by the transition filters The EVENt register is continuously updated by the instrument It can only be read by the user Reading this register clears its contents This register is frequently referred to as the overall register ENABle register The ENABle register determines whether the EVENt bit affects the summary bit refer to Summary bit on page 3 21 Each bit of the EVENt register is ANDed symbol amp with the associated ENABle bit The events of all logical operations of this register are ORed symbol and passed on to the summary bit ENAB bit 0 the associated EVENt bit does not affect the summary bit ENAB bit 1 if the associated EVENt is 1 the summary bit is also set to 1 DDS200 Digital Demodulation System User Manual Remote Control This register can be written and read by the user R
28. first in a command line that is immediately follows a PROGRAM MESSAGE TERMINATOR clears the output buffer 3 28 DDS200 Digital Demodulation System User Manual C 1 Maintenance and Troubleshooting Maintenance Cleaning the Outside A Cleaning the Inside Storage This section discusses the maintenance and troubleshooting that an operator can perform on the DDS200 Digital Demodulation System For a more thorough discussion of maintenance and troubleshooting refer to the service manual The unit does not require regular maintenance Cleaning is basically all the maintenance the unit requires In particular care should be taken that the inlet and outlet vents are kept clean Check the nominal data from time to time Refer to the data sheet for data and tolerances as well as information on appropriate calibration intervals Use a soft lint free duster or brush for cleaning the unit on the outside If the unit is soiled meths or mild detergents may be used Do not use any nitro thinners acetone etc since these solvents may damage the front panel labelling or plastic parts Clean and check above all the inlet and outlet vents WARNING Disconnect the power cord from the rear panel of the DDS200 before opening the instrument Failure to do so could expose you to risk of injury or even death For cleaning the interior remove the covers Remove dust by means of a brush or grease free compresse
29. invalid character Example A in a decimal numeric or 9 in an octal data 123 Exponent too large The magnitude of the exponentis larger than 32000 124 128 130 Too many digits Numeric contains too many digits Numeric data not allowed The command contains a numeric data element in a position where it is not allowed Suffix error The command contains an incorrect suffix DDS200 Digital Demodulation System User Manual Appendix C List of Error Messages Table C 2 Command errors Cont Error Test displayed upon an error queue query number Explanations 131 Invalid suffix The suffix is inappropriate for this device Example nHz is not defined 134 Suffix too long The suffix contains more than 12 characters 138 Suffix not allowed A suffix is notallowed for this command or at this position in the command Example the command RCL does not allow a suffix to be specified 140 Character data error The command contains a faulty character data element 141 Invalid character data Either the character data contain an invalid character or the particular data are not valid for this command Example spelling mistake in parameter specification 144 Character data too long The character data element contains more than 12 characters 148 Character data not allowed The character data element is not allowed for this command or at this position of the command Example the comman
30. it is required that for a reliable identification of an interferer the frequency of occurrence at the calculated center point must not exceed 90 of the frequency at the maxima it can be shown that the condition C I lt SNR 3 dB must be fulfilled Otherwise it is not possible to draw any conclusions as to the presence of an interferer by means of this analysis method The clouds visible in the constellation diagram will then be interpreted exclusively as additive Gaussian noise superimposed on the QAM signal The standard deviation ow can be calculated by means of statistical methods This is done with the interferer present using only the ranges outside the maxima since these ranges are largely unaffected by the other type of noise DDS200 Digital Demodulation System User Manual 2 71 Manual Operation 2 72 From the standard deviation ow the RMS value of the noise power N and the signal to noise ration SNR are obtained directly as follows SNR 10 log P sig N dB where N Q op According to the definition of the DVB Measurement Group the SNR value is a pure baseband quantity This means that the calculated SNR cannot be compared directly with the C N value of the transmission channel The difference between SNR and C N lies in peaking in the constellation diagram 3 dB and in the root cosine roll off filtering 0 441 dB for r 0 15 Phase Jitter As a last step the RMS value of the phase jitter m
31. numeric entry 7 000 page 2 31 LOWER SEARCH LIMIT numeric entry 1 000 SYMBOL RATE VALUE numeric entry 6 900 START AUTO SEARCH STOP AUTO SEARCH ORDER OF QAM AUTO 4 16 32 64 128 256 page 2 33 2 58 DDS200 Digital Demodulation System User Manual Manual Operation Table 2 4 DDS200 Preset Values cont BEEPER page 2 33 CLOCK SYNC LOST ENABLED DISABLED ENABLED DISABLED ENABLED DISABLED ENABLED DISABLED ENABLED DISABLED EQUALIZER SYNC LOST CARRIER SYNC LOST FRAME SYNC LOST MPEG DATA ERROR MPEG DATA CORRECTION ENABLED DISABLED SPECIAL FUNCTION EQUALIZER EQUALIZER MODE AUTO page 2 34 page 2 34 FREEZE OFF CENTRAL TAP POSITION numeric entry 9 ROLLOFF FACTOR 0 15 page 2 35 020 0 25 0 30 MIN BER INTEGRATION BER EXT Connectors X5 X6 active 1 SAMPLE 10 SAMPLES 100 SAMPLES 1000 SAMPLES LOOP BANDWIDTH HIGH page 2 35 MED LOW MPEG DATA OUTPUT REED SOLOMON DECOD page 2 36 2 5 5 5 ER OFF INDICATION BITIN ENABLED MPEG FRAME DISABLED DDS200 Digital Demodulation System User Manual 2 59 Manual Operation Table 2 4 DDS200 Preset Values cont ON OFF 188 BYTES 204 BYTES ALARM REGISTER CLEAR YES page 2 38 page 2 45 NO ALARM THRESHOLDS LEVEL numeric entry 60 dBm page 2 41 numeric entry 1 0E 4 ALARM CONFIG ENABLED page ag DISABLED ENABLED DISABLED ENABLED
32. of a channel increases at the output of the receiver filter since the white noise is decreased to a greater extent than the useful signal which is filtered in the transmitter Moreover both the C N ratio determined by the method described page 2 80 and the C N ratio of the internal noise generator are referred to the bandwidth of the receive channel for example 8 MHz if the 8 MHz filter is selected For an exact value the C N ratio must be corrected in accordance with Figure 2 62 However the method described is appropriate for practical purposes where the C N value is to be determined for a real channel and the test point after the receiver Nyquist filter is not accessible 15 1 0 0 5 C Nreclr C Nc r 0 0 0 5 1 0 0 0 01 0 2 0 3 0 4 0 5 Figure 2 62 Effect of receive filter on C N value C Nrec C N after receive filter C NC C N ahead of receive filter in channel Example With the roll off factor of 0 15 used for DVB signals and a symbol rate of 6 95 Msps the 8 MHz receive channel is utilized fully A C N value of 24 0 dB is set with the internal noise generator of the DDS200 This value is increased by 0 441 dB after the receive filter see Figure 2 62 The theoretical BER for the described receiving conditions can be seen from Figure 2 61 for C N 24 4 dB a BER of approx 1 1E 4 is obtained For the described relationship between the noise generator and the BER all BER
33. parallel The following are descriptions for each of the bus lines for the IEC IEEE interface see Table B 1 Data bus with 8 lines DIO 1 to DIO 8 Transmission is bit parallel and byte serial in ASCH ISO code DIO 1 is the lowest significant and DIO 8 the highest significant bit Control bus with 5 lines m Interface Clear Active LOW resets the interfaces of connected devices to a defined initial condition m ATN Attention Active LOW signals the transmission of interface messages inactive HIGH signals the transmission of device dependent messages DDS200 Digital Demodulation System User Manual B 1 Appendix B IEC IEEE Bus Interface SRQ Service Request Active LOW enables a device to send a service request to the controller REN Remote Enable Active LOW allows switchover to the remote control mode EOI End or Identify In connunction with ATN this line has two functions active LOW denotes the end of data transmission with ATN HIGH and active LOW triggers a parallel poll with ATN 2 LOW m Handshake bus with three lines DAV Data Valid Active LOW signals that a valid data byte is on the bus NRFD Not Ready For Data Active LOW signals that one of the connected devices is not ready to accept data NDAC Not Data Accepted Active LOW until the connected device has accepted the data on the bus Table B 1 Bus Lines
34. preamplifier STATe 110 Useful only with INP ATT AUTO INPutGAIN Md STATe Dataare sent without unit D 6 DDS200 Digital Demodulation System User Manual Appendix D List of Commands SENSe Subsystem Table D 6 SENSe Commands Command Reply data Meaning SENSe FREQuency ddd d Hz Setting of RF frequency CENTer Hz kHz MHz GHz ddd d Hz 30 0 to 900 0 default unit Hz SENSe FREQuency i Query in Hz data not being sent CENTer with unit SENSe FREQuency SEARch dd d dB Entry of threshold for RF search LEVel dd d dB SENSe FREQuency SEAR ch LEVel SENSe QAM INTern EXTern Selection of the source for the BER BERate INT JEXT integration interval internal external SENSeQAM See page 2 34 BERate SENSe QAM dddd Selection of the BER integration BERate _ dddd over 1 10 100 1000 samples INTegration page 94 SENSe QAM BERate INTegration SENSe QAM FILTer MHZ2 MHZ4 MHZ8 Filter selection for QAM SAW filter SAW ui MHZ2 MHZ4 MHZ8 See page 2 30 SENSe QAM FILTer one SAW SENSe CDiagram SPECtrum Selection of measurement type in QAM MEASure ae KCDISPECTERAT IMP Jo NORM Normal SENSe Constellation Diagram QAM MEASure Spectrum Echo Pattern Impairments See page 2 46 Dataare sent without unit DDS200 Digital Demodulation System User Manual D 7 Appendix D List of Commands Table D 6
35. refers to the part of the instrument that performs the Hardware instrument function proper such as signal generation and measurements This does not include the controller The data set exactly represents the hardware functions in the software IEC IEEE bus setting commands cause a modification in the data set The data set management enters the new values for example frequency into the data set but passes them on to the hardware only when requested by the command identifica tion to do so Since this request is always made at the end of a command line the sequence of the setting commands in the command line is irrelevant Immediately before the data are passed on to the device hardware they are verified for compatibility both with the other data and with the device hardware If execution of the setting commands is not possible an execution error message will be sent to the status reporting system All modifications to the data set will be ignored and no new setting made in the device hardware Due to the delayed verification and hardware setting illegal device states may temporarily be set within a command line without causing an error message At the end of the command line a legal device status must be restored Prior to the data transfer to the hardware the settling bit is set in the STATus OPERation Register refer to STATus OPERation Register on page 3 25 The hardware carries out the setting and the bit is reset as soon as settl
36. settings DVT 200 Digital Video Transmitter DDS200 Digital Demodulation System Modulation with built in PRBS generator SPECIAL FUNCTION BER INTEGRATION length of sequence 223 1 bit BER EXT SPECIAL FUNCTION MPEG DATA OUTPUT I Q INVERSION NORMAL or INVERTED not AUTO Description of external BER measurement The DVT 200 Digital Video Transmitter provides a signal which is modulated by means of an internal PRBS pseudo random bit sequence generator The QAM output signal is taken via an attenuator to a coupler where a signal of the same frequency from a noise generator is added The resulting signal can be displayed on a spectrum analyzer for example a 2715 Spectrum Analyzer for determining the C N value see below The signal is then taken to the DDS200 where it is demodulated Of DDS200 Digital Demodulation System User Manual Manual Operation course the noise generator integrated in the DDS200 can be used instead of the external noise generator The received signal is synchronized in terms of carrier and symbol clock the built in equalizer is adapted automatically The serial data are taken from connectors SERIAL CLOCK and SERIAL DATA valid with rising clock edge on the rear of the DDS200 The data is taken immediately after the demapping block before the Reed Solomon decoder the deinterleaver and the energy dispersal section At this point the data have not undergone any error protection measures a
37. shock the grounding conductor must be connected to earth ground Before making connections to the input or output terminals of the product ensure that the product is properly grounded Observe All Terminal Ratings To avoid fire or shock hazard observe all ratings and markings on the product Consult the product manual for further ratings information before making connections to the product Do not apply a potential to any terminal including the common terminal that exceeds the maximum rating of that terminal Replace Batteries Properly Replace batteries only with the proper type and rating specified Do Not Operate Without Covers Do not operate this product with covers or panels removed Use Proper Fuse Use only the fuse type and rating specified for this product Avoid Exposed Circuitry Do not touch exposed connections and components when power is present Wear Eye Protection Wear eye protection if exposure to high intensity rays or laser radiation exists Do Not Operate With Suspected Failures If you suspect there is damage to this product have it inspected by qualified service personnel Do Not Operate in Wet Damp Conditions Do Not Operate in an Explosive Atmosphere Keep Product Surfaces Clean and Dry DDS200 Digital Demodulation System User Manual xi General Safety Summary Xii Symbols and Terms A A Provide Proper Ventilation Refer to the manual s installation instructions for details on ins
38. the above named frequency distribution This effect is shown in Figure 2 56 for a signal distorted by amplitude imbalance DDS200 Digital Demodulation System User Manual Manual Operation 1000 y Vija actual fine V iQ set 1 Q actual fine with noise 1 Q set 0 015 0 010 0 005 N i 0 98 0 000 MM i 0 005 0 010 0 015 0 86 0 9 0 94 102 1 06 11 114 118 VIQ set Figure 2 56 Improvement of accuracy with superimposed noise SNR z 45 dB DDS200 Digital Demodulation System User Manual In Figure 2 56 the scaling for the gain calculated from the measured values containing noise is increased by a factor of 1000 Thus the resolution for the analysis is improved by a factor of approximately 1000 The same applies to the calculation of the other parameters The background noise is present on every real transmission path and results in a drastic improvement of the resolution of the calculated parameters To achieve meaningful results a sufficiently large number of measured I Q values are needed to form the basis for calculating the parameters in question law of large numbers With the DDS200 parameter calculation is based on almost 1 000 000 measured values shown on the display which affords the necessary confidence level With this data acquisition rate a typical refresh rate of results of
39. the device 213 Init ignored the initialization of a measurement was ignored since another measurement was already being carried out 214 Trigger deadlock The trigger cannot be processed The trigger source for releasing a measurement is setto GET and the subsequent query is received The measurement cannot be started if GET is not received GET die darauf folgende Query wird empfangen Die Messung kann ohne den Empfang von GET nicht gestartet werden GET however generates an interrupted error 215 Arm deadlock The arming signal cannot be processed 220 Parameter error The command contains a faulty or invalid parameter Example 221 Settings conflict There is a setting conflict between two parameters Example FM1 and PM1 cannot be switched on simultaneously 222 Data out of range The parameter value is outside the legal range as defined by the device Example the command RCL only allows entries in the range 0 to 49 223 Too much data The command contains too many data Example the device has not enough storage capacity 224 Illegal parameter value The parameter value is invalid Example an invalid character data element is specified 230 Data corrupt or stale Data are incomplete or invalid Example the device has aborted a measurement 231 Data questionable The measurement accuracy is suspect 240 Hardware error The command cannot be executed because of a hardware problem in
40. the points are obtained for each component Next the distances between the points are averaged separately for I and Q resulting in an average I and an average Q distance expressed as and From this the amplitude imbalance is determined V2 1 where v min vy Vo and v max vy Vo The result will always be 20 because the I and Q paths of the demodulator cannot be unambiguously assigned to the corresponding paths of the DDS200 Digital Demodulation System User Manual Manual Operation modulator since it is not known if the phase locks at n 90 For all calculations described below the previous results are modified such that the effect of amplitude imbalance is eliminated In other words the center points are calculated that would be obtained if there was no amplitude imbalance W Phase Error The phase error PE can be determined from the modified center points The gradients of the regression lines drawn through the center points in the I and Q directions are calculated by separate evaluation of the I and Q compo nents From the gradients angles and 0 are obtained directly using the arcsin function 8 e oJ Again for all further calculations the center points are determined that would be obtained if no phase error was present Carrier Suppression To calculate the carrier suppression CS the distance between the calculated and the ideal center points is determined From t
41. 0 dBuV to 117 dBUV to the 75 Q RF input connector using a BNC cable The 75 Q RF input connector may be located on the front or the rear panel depending on the option On the rear panel the 75 Q female connector X9 is also a BNC type RF input DDS200 Digital Demodulation System The DDS200 Digital Demodulation System stores the current setup in a nonvolatile memory On power on the instrument reinstates the same configura tion as before power off The ten setups stored with STO RCL are also saved in this memory The battery status is indicated on power on If the lithium battery which also supplies the built in clock is discharged approximately after five years it should be replaced as described in Replacing the Battery on page 4 2 Opon power on the unit carries out a self test to check that all installed assemblies are present and that the instrument is functional Errors found are indicated on the initial display Minor errors in the hardware can only be detected by means of measurements requiring a special setup DDS200 Digital Demodulation System User Manual 1 15 Preparation for Use Installing Options Installing a printer Serial Interface 1 16 Various options hardware modules are available to expand the DDS200 Detailed instructions describing the installation steps are enclosed with each option The options can be inserted in the guide rails from the rear after removing the covers top and bottom and
42. 000 HHz 66 7 dBu RCL RF STO RF Figure 2 8 RF menu DDS200 Digital Demodulation System User Manual Manual Operation LEDs Special operating states are signalled by LEDs on the front panel of the DDS200 The following LEDs are available m Status LEDs next to the display to indicate input signal errors signal and sync m Status LEDs next to the display to indicate remote control operation REM LLO SRQ m LED nextto the SPEC FUNC key lights when a special function is selected m LED nextto the ALARM key lights when there is an alarm The SIGNAL LED signals the absence of an appropriate input signal at the corresponding receive frequency RF level too low or too high RF squelch The SYNC LED indicates synchronization problems With these two LEDs it is possible to have a general overview of the test signal applied The REM LED signals that the unit is remote controlled SRQ and LLO are status messages for the IEC 625 IEEE 488 bus refer to Remote Control STATE SIGNAL SYNC AUDIO REM uo Q sa The LED located above the SPEC FUNC key lights up when a special function is activated in this menu The unit may not be in normal operation The LED next to the ALARM key signals the presence of an alarm DDS200 Digital Demodulation System User Manual 2 11 Manual Operation Soft Keys The soft keys on the right of the display are allocated different functions depending on the
43. 2 37 error bit 2 37 outputs assignment and functions 2 85 parallel data PLL 2 37 MPEG outputs configure 2 36 N NICAM 1 6 Numbers error descriptions C 1 Numeric keypad description 2 14 O Operation manual 2 1 Options installing 1 16 Output buffer 3 19 DDS200 Digital Demodulation System User Manual Index P Parallel data frame size 2 37 Parallel poll 3 27 Parameters remote control 3 9 Phase error 2 69 Phase Jitter 2 72 Power key 1 2 Powering on 1 12 procedure 2 2 Preparation for use 1 1 Preset values MTD200 2 58 Presetting 2 16 Printer 1 4 1 16 hardcopy key 2 17 Programming examples E 1 initialization E 1 list management E 2 readout of device settings E 2 sending device settings E 2 service request E 4 switchover to manual control E 2 QAM calculated max and min values 2 74 default value 2 33 miscellaneous errors 2 76 order 2 33 selftest 4 3 QAM demodulator description 2 26 Queries 3 9 QuickBASIC incorporating E 1 R READ commands D 12 Readout device settings programming example E 2 Real time clock 4 2 Reed Solomon decoder 2 36 Register SCPI status 3 19 Remote control buffer 3 16 command identification 3 16 commands 3 4 common commands 3 12 CONFigure subsystem D 15 data set 3 17 device hardware 3 17 displays 3 2 HCOPy subsystem D 19 DDS200 Digital Demodulation System User Manual input 3 16 INPut subs
44. 6 NOTE For reading out the equalizer coefficient the equalizer is automatically set to the FREEZE mode using the SPECTRUM and the ECHO PATTERN functions The BER may deteriorate during the readout This is particularly noticeable when MPEG data are processed at the same time In the SPECTRUM display see Figure 2 45 the coefficients are used for calculating the phase and amplitude frequency response in the transmission channel et ANT AT aA UV a CE MAS E EE REED ERES ERE 8 GEN Ei ER tt tt tt tt 0 5 FeFs 0 5 LENLISCENLZN Sa Sebi VERE PIN Leones Eee Figure 2 45 MEASURE SPECTRUM menu The frequency scale is based on the current symbol rate Fs Consequently in the range 0 5 to 0 5 the spectrum of the whole signal including the Nyquist frequencies is displayed The unit of the amplitude scale is decibel dB the unit of the phase scale is degree Spectrum scales are fixed and cannot be varied In the ECHO PATTERN display see Figure 2 46 the equalizer coefficients are used for calculating the echos or reflections in the receive channel DDS200 Digital Demodulation System User Manual Manual Operation 10 z0 J 10 15 ZO LSTS Figure 2 46 MEASURE ECHO PATTERN menu in the QAM demodulator mode The echo diagram clearly shows the position of the central tap in this case position 9 It can be configured using a specia
45. 6 43dB 256 0 596 1 356 9 471 46dB DDS200 Digital Demodulation System User Manual 2 75 Manual Operation The term modulation error ratio and the prescribed method of calculation were declared international standard by the DVB Measurement Group Some test systems however specify the error vector magnitude so the conversion rule for the two quantities is given in Table 2 7 The two quantities differ only in the reference used The modulation error ratio is referenced to the RMS value of the baseband signal the error vector magnitude is referenced to the peak value Table 2 7 Limit values for modulation error Order MER EVM EVM MER MER EVM dB EVM MER dB 4 EVM MER EVM EVM MER MER EVM 16 EVM MER 1 342 MER EVM 1 342 EVM MER 2 56dB MER EVM 2 56dB 32 EVM MER 1 304 MER EVM 1 304 EVM 2 31dB MER EVM 2 314 64 EVM MER 1 527 MER EVM 1 527 JEVM MER 3 68dB MER EVM 3 6808 128 EVM 1 440 MER EVM 1 440 EVM 3 17dB MER EVM 3 17dB 256 EVM 1 627 MER EVM 1 627 EVM 4 23dB MER EVM 4 23dB m Other Errors This subsection describes the effects of errors on the QAM signal that have not been investigated before Impulse noise Impulse noise is caused by switching and ignition processes The pulses are very short and of widely differing shapes Since the analysis of the constellation diagram is bas
46. AL FUNCTION menu 2 34 Figure 2 30 SPECIAL FUNCTION MPEG DATA OUTPUT menu iurc 4e Ux ERN ERE E CHI 2 36 Figure 2 31 ALARM CONFIG 2 38 Figure 2 32 ALARM Register menu 2 40 Figure 2 33 ALARM TRESH menu 2 41 Figure 2 34 ALARM STATISTICS menu 2 42 DDS200 Digital Demodulation System User Manual V Table of Contents vi Figure 2 35 ALARM PRINT menu in the QAM demodulator mode 2 43 Figure 2 36 ALARM PRINT LAST LINES menu 2 44 Figure 2 37 MEASURE menu 2 46 Figure 2 38 Recording the BER running BER calculation over 10 samples 2 49 Figure 2 39 Noise at input no QAM signal e 2 50 Figure 2 40 QAM signal with unsynchronized carrier and symibolrate cate er pe ne SHOTS 2 51 Figure 2 41 QAM signal with unsynchronized carrier 2 51 Figure 2 42 Correctly synchronized 64QAM signal 2 52 Figure 2 43 MEASURE CONSTELLATION DIAGRAM menu 2 52 Figure 2 44 Function of GATE TIME and GATE CNT 2 53 Figure 2 45 MEASURE SPECTRUM menu 2 56 Figure 2 46 MEASURE ECHO PATTERN menu in the QAM demodulator mode 2 57 Figure 2 47 C
47. ALARm ON OFF QAM SYNChron 1 0 STATe CONFigure ALARm QAM SYNChron STATe Meaning Mask for QAM RF level alarm on off See page 2 38 Mask for QAM BER on off See page 2 38 Mask for QAM synchronization alarm on off See page 2 38 DDS200 Digital Demodulation System User Manual D 15 Appendix D List of Commands Table D 10 CONFigure Commands Cont Command Data Reply data Meaning CONFigure ALARm ON OFF Mask for data error alarm with QAM QAM DERRor 110 QUART STATe See page 2 38 CONFigure ALAR m QAM DERRor STATe CONFigure ALARm ON OFF Mask for RF level threshold in QAM QAM RF LEVel 110 ove one STATe See page 2 38 CONFigure ALARm QAM RF LEVel STATe CONFigure ALARm ON OFF Mask for beeper clock sync lost on QAM BEEP 1 0 of SYNc CLOCK pee Nave OA STATe CONFigure ALARm QAM BEEP SYNc CLOCK STATe CONFigure ALARm ON OFF Mask for beeper equalizer sync lost QAM BEEP 110 RATE SYNc EQUalizer pags 2 40 STATe CONFigure ALARm QAM BEEP SYNc E QUalizer STATe D 16 DDS200 Digital Demodulation System User Manual Appendix D List of Commands Table D 10 CONFigure Commands Cont Command Data Reply data Meaning CONFigure ALARm onjo Mask for beeper carrier sync lost on QAM BEEP 110 Tot SYNc CARRier STATe CONFigure ALARm QAM BEEP SYNc
48. ASURE menus is that a noise generator can be connected The noise generator in the OFF condition is activated with the ADD NOISE key The desired value for the C N ratio can now be entered in dB When a noise signal is added to the information signal conclusions can be made about the system characteristics DDS200 Digital Demodulation System User Manual 2 47 Manual Operation For further information refer to BER as a Function of C N Calculation of Further Parameters on page 2 82 The noise power is always derived from the noise power set in the instrument in connection with the selected channel bandwidth refer to SAW Filter on page 2 31 BER Measurement During normal reception the BER is continuously calculated in the DDS200 The raw BER BER before any error correction is made is indicated The BER measurement is fully automatic The instrument selects the required integration rate depending on the error rate measured The integration rate is indicated in brackets after the measured value It is always specified in samples the duration of a sample depends on the selected order of QAM and on the symbol rate With 64 QAM and 6 900 MSPS the BER events occurring in 241 55 ms are combined to one sample The second value in brackets states the number of samples collected by the instrument after the measurement is completed last count The first value indicates the recorded samples The indication 133 1000 means that 133 of t
49. Action DDS200 Digital Demodulation System User Manual Appendix D List of Commands STATus Subsystem NOTE The commands listed below refer to the OPERation register The commands can be used for the QUEStionable register as well by replacing OPERation by QUEStionable Table D 2 STATus Commands Command Reply data Meaning STATus Returns the next item from the error event queue and QUEue removes it from the queue NEXT identical to that of SY ST ERR STATus PRESet Configures the SCP I and device dependent Status Data structures STATus Returns the contents of the OP ERation EVENt status OPERation ee EVENtP STATus Returns the contents of the OP ERation CONDition status OPERation eat CONDition STATus Sets R eturns the enable mask which allows true OP ERation ddd ate event register to be reported in the ENABle STATus OPERation ENABle D 2 DDS200 Digital Demodulation System User Manual Appendix D List of Commands Table D 2 STATus Commands Cont Command STATus OPERation PTRansion STATus OPERation PTRansion Meaning Sets Returns the positive transition filter STATus OPERation NTRansion STATus OPERation NTRansion DDS200 Digital Demodulation System User Manual Sets R eturns the negative transition filter D 3 Appendix D List of Commands SYSTem Subsystem Table D 3 SYSTem Commands Command Data SYSTem TIME 0 to 23 0 to 59 0 to
50. BDS seh s tbid e p RR e e cena n E fete rue ao SOft KeyS is is eee tef o ar abo o Er RLW RUN IR RE LIS S eres CUSO KEYS o eo OR OP ER Rh C E e ERR RR Groene Nume ricsKeypad seh ere Rag RI Reds Selecting Settings 5 gis oq ce eR E e CART SCR RATE e e RERO reque Editing Text and Presetting the Unit i oa IURE GR UR XU Pea RT DDS200 Digital Demodulation System User Manual xi xiii Es le al AN Oo OO CO eRe 0 1 11 1 12 1 13 1 13 1 15 1 15 1 15 1 16 1 16 1 16 1 17 2 2 2 2 2 3 2 3 2 4 2 4 2 6 2 8 2 8 2 9 2 11 2 12 2 13 2 14 2 14 2 15 2 16 Table of Contents Remote Control Hardcopy Key RS e RC wa 2 17 STO RCL Storing Device Settings 2 17 Hard Keysscumn creen evt LS RECHTE Ae BU BAC Pe Ee 2 18 General Device Settings se cenos en nE eee ee ec EA e 2 19 Introduction e EM Vale Bae SCIRE eA ee aha Ska S 2 19 SETUP Menus estas ete CU REUS ICT RECHNER E SERA 2 19 Operation as Demodulator for Quadrature Amplitude Modulated QAM Signals ee Re e mh hy a 2 26 OVEIVIEW uuu DUCES ALR els TURIS EGS Re 2 26 INPUT Menu Input Selection 2 27 RE SR RESET Ae She ed at eee SIE E bet 2 29 STATUS Men eset auge usb
51. CARRier STATe CONFigure ALARm ON OFF Mask for beeper frame sync lost on QAM BEEP 110 SYNc FRAMe STATe CONFigure ALARm QAM BEEP SYNc FRAMe STATe CONFigure ALARm ON OFF Mask for beeper MPEG data error QAM BEEP 110 DERRor STATe CONFigure ALARm QAM BEEP DERRor STATe See page 2 30 DDS200 Digital Demodulation System User Manual D 17 Appendix D List of Commands Table D 10 CONFigure Commands Cont Command Data Reply data Meaning CONFigure ALARm Tonjo Mask for beeper MPEG data QAM BEEP 10 correction on off CORRection STATe CONFigure ALARm QAM BEEP CORRection STATe CONFigure ALARm ddd dd Failure threshold for QAM RF level QAM RF LEVel Unitas UNIT LEV POW ddd dd 22m CONFigure ALARm Unitas d ecu ue QAM RF LEVel UNIT LEV POW x CONFigure ALARm ddE d Failure threshold for QAM BER QAM BERate ddE d See page 2 38 CONFigure ALARm QAM BE Rate CONFigure ALARm RESet Erasing the alarm register and the Statistical information Dataare sent without unit D 18 DDS200 Digital Demodulation System User Manual Appendix D List of Commands HCOPy Subsystem Table D 11 HCOPy Commands Command Data Reply data Meaning HCOPy IMMediate Releasing the printing operation See page 2 17 HCOPy ABORt Termination of printing See page 2 17 HCOPy ALARm Printing of statistical informat
52. DISABLED ENABLED DISABLED NEWEST LINE PRINT Entry of number of last lines page 2 43 to be printed start with PRINT 5 Entry of range of lines to be printed start with PRINT ACTUAL ALARM toggle key STATISTICS page 2 41 MEASURE CONSTELL DIAGRAM GATE TIME numeric entry 100 ms page 2 46 page 2 50 GATE COUNT numeric entry 1 toggle key FREEZE toggle key ECHO PATTERN page 2 55 SPECTRUM page 2 55 QAM PARAMETERS page 2 54 ADDITIONAL NOISE Toggle key for switch over numeric entry page 2 46 between numeric value and C N 62dB OFF 2 60 DDS200 Digital Demodulation System User Manual Manual Operation Table 2 4 DDS200 Preset Values cont SETUP TIME amp DATE TIME numeric entry DATE numeric entry REMOTE IEC 625 iEEE488 numeric entry 6 PRINTER PRINTER TYPE EPSON COMP R amp S PUD COMP HP COMP de AFTER PRINTOUT LEVEL UNITS dBpW dBuW dBm dBuV uV mV LCD INVERS ON OFF DDS200 Digital Demodulation System User Manual 2 61 Manual Operation Examples of Application 2 62 This section is divided into the following subsections Application and Interpretation of Constellation Diagram page 2 62 Explanation of Calculated Parameters Formulas and Limit Values page 2 68 Selection of Integration Time for BER Measurements page 2 79 BER Measurements with External Equipment page 2 80 BER as a function of C N Calculation of Further
53. DS200 Digital Demodulation System User Manual Preparation for Use Table 1 1 Legend for front view Cont Controls Connectors Description FUNCTION PRESET This key is used to reset the unit to the FUNCTION factory default settings EON STO This key stores device configurations E 3 RCL This key loads device configurations ae HARDCOPY This key prints the screen display to the connected print RF This front panel 75 Q RF input connector is provided as an alternative to the rear panel RF input connector customer specific the actual configuration is indicated in the INPUT menu VIDEO VIDEO This connector location is for future use C Q SIG This connector location is for future use 750 AUDIO 1 L This connector is for future use AUDIO 1L 2R Q AUDIO 2 R X This connector is for future use LJ T This connector is for future use e een AUDIO This pushbutton is for future use 1 4 DDS200 Digital Demodulation System User Manual Preparation for Use Rear Panel Rear view of DDS200 VIDEO 750 Q750 PILOT O D Uum M ne MPEG DATA ASI o ee e RF75Q _ 500 _1 500 ZERO REF 9 920 e X99 e xe X12 ORL ORECEVER NCAM DATA CLOCK 200007 NIC DATA CLOCK OO 100 120V 2 5A 220 240V 1 3A UTOMATIC VOLTAGE
54. DTH When the LOOP BANDWIDTH key is pressed the loop bandwidth for carrier recovery can be configured The typical capture range for carrier recovery is more than 5 of the symbol rate This corresponds to approximately 350 kHz in the case of standard DVB signals This wide permanently set capture range is sufficient for any kind of application The dynamic characteristic can be changed with the aid of the LOOP BANDWIDTH function The choices for changing the dynamic characteristic using the LOOP BAND WIDTH function are as follows DDS200 Digital Demodulation System User Manual 2 35 Manual Operation 2 36 m A wide loop bandwidth be chosen if the phase of the input signal is has considerable jitter In this case most of the phase jitter of the signal to be analyzed can be compensated for m The medium loop bandwidth MED is ideal for general applications m The narrow bandwidth LOW can be chosen when the jitter in the signal is exceptionally low The lower the loop bandwidth the more reliable the recovery of the transmitted signal In the case of problems refer to the constellation diagram and the calculated parameters particularly phase jitter Selected loop bandwidth High Med Low Set loop bandwidth S ymbol rate 10 2 5x10 10 3 The specified loop bandwidths are normalized to the symbol rate In the position HI and a symbol rate of for instance 6 900 MSPS the bandwidth of the loop filter is 69 kHz
55. E bus refer to Appendix A IEC IEEE Bus Interface Via IEC IEEE bus CALL IBLOC efa Set instrument to manual control DDS200 Digital Demodulation System User Manual 3 3 Remote Control IEC IEEE Bus Messages Interface Messages Device Dependent Messages Commands and Responses 3 4 The messages transmitted on the data lines of the IEC IEEE bus refer to Appendix A IEC IEEE Bus Interface can be subdivided into two groups W Interface messages m Device dependent messages Interface messages are transmitted on the data lines of the IEC IEEE bus with the control line ATN active They are used for communication between the controller and the instrument and can only be sent by a controller with controller function on the IEC IEEE bus There are two groups of interface messages m Common commands Addressed commands Common commands affect all devices connected to the IEC TEEE bus without any addressing being required whereas addressed commands only affect devices addressed as a listener The relevant interface messages are listed in Appendix A IEC IEEE Bus Interface The device dependent messages are transmitted on the data lines of the IEC bus with the control line ATN not active The ASCII code is used for data transmission Device dependent messages are differentiated according to the direction in which they are sent via the IEC IEEE bus Commands Commands are messages sent by the controller t
56. ELETE FGHIJELMWH CHARACTER SAVE amp EXIT Figure 2 26 STO EDIT TEXT menu When the EDIT TEXT key is pressed the available characters are displayed Characters can be selected using the cursor keys Pressing the GET CHAR ACTER key adds the selected character to the MEMORY TEXT The cursor can be moved in the MEMORY TEXT to the right or left using the RIGHT and LEFT cursor keys The DELETE CHARACTER soft key clears the character in front of the cursor A maximum of eight characters is allowed for RF memory number identification When the SAVE amp EXIT key is pressed the MEMORY TEXT is assigned to the selected RF memory number is displayed at the top right of the display Select the STATUS menu using the STATUS key in the MAIN FUNCTION block see Figure 2 27 In this menu all main device settings are displayed This particularly applies to the order of QAM parameters the symbol rate and the selected SAW filter Settings that affect input selection or attenuator and preamplifier settings must be made in the INPUT menu DDS200 Digital Demodulation System User Manual Manual Operation OAM STATUS SET RF RF LEVEL 330 000 HHz 66 7 dBu 2 Figure 2 27 STATUS menu SAW FILTER The DDS200 has three slots for accommodating SAW filters One or two filters can be inserted in addition to the 8 MHz filter which is standard The required filter is selected by pressing the SAW FILTER BW soft key several times Un
57. MEASURE CONSTELL DIAGRAN GATE TIME ms GATE CNT 1 HOLD FREEZE ADD NOISE OFF Figure 2 43 MEASURE CONSTELLATION DIAGRAM menu For further examples and a description of individual errors parameters refrer to Application and Interpretation of Constellation Diagram on page 2 62 2 52 DDS200 Digital Demodulation System User Manual Manual Operation Using the GATE TIME GATE CNT MAX HOLD and FREEZE keys you may adapt the constellation diagram to your special requirements Operation in the constellation analyzer mode is illustrated in Figure 2 44 Collection of Graphic Collection of Graphic Collection of Graphic measured 1 0 evaluation of measured 1 0 evaluation of measured 1 0 evaluation of values within measured values values within measured values values within measured values GATE TIME and display GATE TIME and display GATE TIME and display Display range for GATE CNT 1 rate gt rae gt rae gt Display range for GATE CNT 2 gt gt gt m Display range for GATE CNT 23 gt gt Figure 2 44 Function of GATE TIME and GATE CNT Using the GATE TIME key a collection time between 2 ms and 1000 ms can be set Within this period the DDS200 stores the received I Q value pairs every 740 ns Thus 1 351 million I Q values are available every second Subsequently the data are read again from the memory and displayed This procedur
58. PACE 20 Activates text variable 20 characters CALL IBWRT efa SENS FREQ CENT Calls for frequency setting CALL IBRD efa FRequenz Reads in value EAmode SPACE 20 Activates text variable 20 characters CALL IBWRT efa INP ATT AUTO Calls for attenuator control mode CALL IBRD efa EAmode Reads in value REM kkkkkkkkkkkkkk Displays values on screen kkkkkkkkkkkkkk PRINT RF Frequenz MHz FRequenz PRINT RF Regl Mode EAmode Not used in the DDS200 Digital Demodualtion System Command Synchronization E 2 The different synchronization modes stated in the following example are described in Command Sequence and Synchronization on page 3 18 DDS200 Digital Demodulation System User Manual Appendix E Programming Examples REM xesexieie Examples of command synchronization eeeeeeeeeeex REM The execution time of command INP ATT AUTO is relatively long REM more than 3 s This delay shall guarantee that the next command is REM only executed after the settling time of the attenuator is over REM Mode 1 Use of WAI eeeeeeccecck CALL IBWRT efa INP ATT AUTO ON WAI SENS FREQ CENT 100MHZ REM kkkkkkkkkkkk Mode 2 Use of 0PC kkkkkkkkkkkk OpcOk SPACE 2 Provides space for OPC response CALL IBWRT efa INP ATT AUTO ON OPC
59. R Elf Figure 2 14 RECALL menu The contents of a memory location can be recalled in a similar way Press the RCL key and enter the number of the memory location required The overall device setting available under the memory location number selected is recalled after pressing the ENT key The unit returns to the measurement display with the overall device setting restored Hard Keys The Main Function hard keys allow the access to the following menus MODE Refer to Mode Key Selecting the Mode on page 2 25 INPUT Refer to INPUT Menu Input Selection on page 2 27 RF Refer to RF Menu on page 2 29 STATUS Refer to STATUS Menu on page 2 30 MEASURE Refer to MEASURE Menu on page 2 46 SETUP Refer to SETUP Menu on page 2 19 ALARM Refer to ALARM Menu on page 2 38 SPEC FC Refer to SPECIAL FUNCTION Menu on page 2 34 2 18 DDS200 Digital Demodulation System User Manual Manual Operation General Device Settings Introduction The general device settings are settings which are independent of the installed hardware or the mode selected and are accessed through the SETUP menu SETUP Menu In the SETUP menu the following basic device settings are performed Setting time and date Menu SETUP TIME AND DATE Setting the IEC bus address Menu SETUP REMOTE IEC625 IEEE488 Setting the serial interface parameters Menu SETUP REMOTE RS232 Selecting the type of printer Menu SETUP PRINTER Selection of level units Menu SETUP LEVEL UNIT
60. REM Here the controller may control other devices CALL IBRD efa OpcOk Waits for 1 from OPC REM kkkkkkkkkkkk Mode 3 Use of OPC kkkkkkkkkkkkkk REM To enable the Service Request function when using a GPIB driver from REM National Instruments the Disable Auto Serial Poll setting has to be changed to yes by means of IBCONF CALL IBWRT efa SRE 32 Enables Service Request for ESR CALL IBWRT efa ESE 1 Sets Event Enable bit for Operation Complete bit ON PEN GOSUB OpcReady Initializes Operation Complete routine PEN ON CALL IBWRT efa INP ATT AUTO ON OPC REM Continues main program in an endless loop STOP End of program OpcReady REM When the attenuator is settled this subroutine is branched to REM Programming of suitable response to OPC Service Request RETURN REM kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk DDS200 Digital Demodulation System User Manual E 3 Appendix E Programming Examples Service Request E 4 The Service Request routine requires an extended device initialization during which the corresponding bits of the Transition and Enable Registers are set To enable the Service Request function when using a GPIB driver from National Instruments the Disable Auto Serial Poll setting of the driver has to be changed to yes by means of IBCONF In this example the commands are used in short form INCLUDE c qbasic qbdecl bas CLS
61. RM CONFIG menu two asterisks are entered in the respective column These asterisks indicate that the alarm has been masked and cannot trigger an alarm message DDS200 Digital Demodulation System User Manual 2 39 Manual Operation 2 40 Pressing the ALARM key in the MAIN FUNCTION block causes the alarm register to be displayed see Figure 2 32 unn ALARM SET RF RF LEVEL 330 000 MHz 66 7 dBuv DATE TIME REGISTER CLEAR gad ALARM THRESH ALARM COHFIG PRINT STATISTICS Figure 2 32 ALARM Register menu Alarm messages are entered in the register in chronological order The latest entry is entered in the lowest line The display mode is such that the line entered last is displayed at the bottom of the screen when the LINE NEWEST soft key is pressed The number at the beginning of each line indicates the currently used line of the alarm register Any line of the alarm register can be displayed by entering a number terminate with ENT or by means of the cursor keys provided LINE MAN is first selected In this case the NEWEST LINE field is blanked Newly arriving messages continue to be entered The current alarm message is displayed when the LINE NEWEST soft key is pressed again The indication is switched back to the current alarm message The register contains 1000 lines If this number is attained entered messages are automatically overwritten starting at line 0 In thi
62. ROR TIME would mean that faulty MPEG data were received for 0 13 of the seconds of the monitoring period At this point it cannot be distinguished whether the error lasted for one second or whether it occurred several times within this period Detailed error information can be obtained from the MPEG DATA ERROR CNT and MPEG DATA CORR CNT counters which indicate the absolute number of faulty MPEG frames detected MPEG DATA ERROR CNT 1 frame comprises 188 information bearing bytes or the absolute number of corrected bytes MPEG DATA CORR CNT When the alarm register is cleared both counters are reset to 0 The counting limit is 4 294 836 225 When this number is reached the counter stops In the worst case an overflow of the ERROR counter occurs after 5 88 hours of continuous errors at a symbol rate of 6 9 MSPS with 640AM modulation In practice the number of faulty MPEG frames is below 1 which makes the measurement time of the ERROR counter to be more than three weeks DDS200 Digital Demodulation System User Manual Manual Operation NOTE The two counters MPEG DATA ERROR CNT and MPEG DATA CORR CNT are reset to 0 when the alarm register is cleared If in the course of time more than 1000 entries are made in the alarm register the MONITORING TIME in the register and the statistical calculation are referred to the period indicated in the register but the counters are not reset They show the total count since the register was clea
63. S Selection of the LCD display mode Menu SETUP the basic device settings are displayed in the basic setup menu see Fig ure 2 15 From this menu the corresponding submenus can be accessed by pressing the associated soft key SETUP RF RF LEVEL 383 250 MHz 37 4 dBu 05 01 96 FIRMWARE 10 44 36 DATE REMOTE PRIHTER LEVEL UHITS 9600 8 H 1 PRINTER EPSOH COMPATIBLE LCD IHVERS TESTING SYSTEM HO ERROR FOUND OH Figure 2 15 Menu SETUP With the LCD INVERS ON OFF soft key it is possible to change between two display modes LCD INVERS ON Dark letters on white background LCD INVERS OFF White letters on dark background DDS200 Digital Demodulation System User Manual 2 19 Manual Operation The display mode does not affect hardcopy or print functions Time Date Menu Setting Date and Time On pressing the TIME DATE soft key the setup menu for the time and date is displayed see Figure 2 16 The time and date of the built in battery backed crystal clock can now be set The time is for storing alarm messages together with the time of an event and for specifying the time on printed reports SETUP TIHE AND DATE RF RF LEVEL 363 250 MHz 28 7 dBu TIME 10 DATE PRESS ENTER TO SET TIME OF DATE Figure 2 16 SETUP TIME DATE Menu Press the TIME soft key to set the time The time indicated is the system time at the moment of key actuation To change the time enter the time via t
64. SENSe Commands Cont Command Data Reply data Meaning SENSe QAM ON OFF QAM mode ADD NOISE on off NOISe MODe ON OFF See page 2 46 SENSe QAM NOISe MODe SENSe QAM dd d dB QAM mode ADD NOISE NOISe dd d dB Set value 6 0 to 62 0 dB SENSe QAM See page 2 46 NOISe SENSe QAM NORMal MAXH FREeze Setting the type of integration for CD INTegration NORM FRE the QAM constellation diagram SENSe QAM See page 2 46 CD INTegration SENSe QAM ddddd dd s Setting the integration time for the CD INTegration TIME ddddd dd amp Cons NON SENSe QAM 2 0 1000 ms CD INTegration TIME pee page 08 SENSe QAM ddddd Setting the integration time for the CD INTegration COUNt i ddddd DELE SENSe QAM 2 to 1000 ms CD INTegration COUNt see page SENSe QAM AUTO FREeze OFF Setting the equalizer for QAM EQUalizer MODE AUTO OFF See page 2 34 SENSe QAM EQUalizer MODE SENSe QAM dd Position of central coefficient EQUalizer CENTral TAB dd Ranch 0 to 23 SENSe QAM See page 2 34 EQUalizer CENTral TAB Dataare sent without unit D 8 DDS200 Digital Demodulation System User Manual Appendix D List of Commands Table D 6 SENSe Commands Cont Command Data Reply data Meaning SENSe QAM R015 R020 R025 R030 Setting the rolloff factor for QAM
65. SOM COMPATIBLE TESTING SYSTEM HO ERROR FOUND Figure 2 12 PRESET menu DDS200 Digital Demodulation System User Manual Manual Operation After selection of a preset key the unit queries if the settings are to be reset If this is confirmed by the YES soft key the unit is reset with the factory set settings Press the PRESET key after a new power up of the DDS200 if the settings of the previous session are not exactly known Hardcopy Key On pressing the Hardcopy key the current screen contents is output on the printer The selection of the type of printer is described in Printer Menu Selecting the Type of Printer on page 2 23 STO RCL Storing Device The user can store or recall up to 10 specific device settings with the STO and Settings RCL keys Thus he can retain his own settings even after the unit has been used by other persons Press the STO key to store the current overall device setting see Figure 2 13 STORE RF RF LEVEL 42 220 MHz 20 2 dBu STORE SETUP TO SETUF MEMORY M Figure 2 13 STORE menu For storing enter a memory location number under which the setup can be recalled later Use the numeric keys for this purpose The range of values is 0 to 9 After pressing the ENT key the setup is stored and the unit returns to the measurement display DDS200 Digital Demodulation System User Manual 2 17 Manual Operation RECALL RF RF LEVEL 45 250 MHz 16 4 dBu RECALL SETUP FROM SETUP MEMO
66. T QUES EVEN CALL IBRD efa Ques IF VAL Ques AND 16384 gt 0 THEN PRINT STAT QUES REG 14 IF VAL Ques AND 8192 gt 0 THEN PRINT STAT QUES REG 13 IF VAL Ques AND 4096 gt 0 THEN PRINT STAT QUES REG 12 IF VAL Ques AND 2048 gt 0 THEN PRINT STAT QUES REG 11 DDS200 Digital Demodulation System User Manual E 5 Appendix E Programming Examples IF VAL Ques AND 1024 gt O THEN PRINT STAT QUES REG 10 IF VAL Ques AND 512 0 THEN PRINT STAT QUES REG 9 RETURN Operationstatus Reads Operation Status Register Oper SPACE 20 Preallocates text variable using spaces CALL IBWRT efa STAT OPER EVENt Clears register on reading CALL IBRD efa Oper and rejects value Oper SPACE 20 Preallocates text variable using spaces CALL IBWRT efa STAT OPER COND CALL IBRD efa Oper IF VAL Oper AND 16 gt 0 THEN PRINT Event STAT OPER REG not yet terminated IF VAL Oper AND 16 0 THEN PRINT Event STAT OPER REG not yet terminated RETURN Esrread Reads Event Status Register Esr SPACE 20 Preallocates text variable using spaces CALL IBWRT efa ESR Reads ESR CALL IBRD efa Esr IF VAL Esr AND 1 gt 0 THEN PRINT Operation complete IF VAL Esr AND 4 gt 0 THEN GOTO Failure IF VAL Esr AND 8 gt 0 THEN PRINT Device dependent error IF VAL Esr AND 16 gt 0 THEN GOTO Failure IF VAL Esr AND 32 gt 0 THEN GOTO
67. UDio SOURce NICAM This command line is shown in full length and contains two commands separated by a colon Both commands belong to AUDio command system that is they have two common levels In the shortened command line the second command starts at the level below AUDIO The colon after the semicolon must be omitted The shortened form of the command line is CALL IBWRT efa AUDio MODE AUTO SOURce NICAM However a new command line always starts with the full path DDS200 Digital Demodulation System User Manual Remote Control Example CALL IBWRT efa AUDio MODE AUTO CALL IBWRT efa AUDio SOURce NICAM Responses to Queries Unless otherwise expressly specified a query is defined for each setting command The query is generated by appending a question mark to the associated setting command The SCPI rules imposed on the query responses are somewhat stricter than those of the IEEE 488 2 standard 1 The required parameter is sent without header Example AUDio MODe Response AUTO 2 Numeric values are output without unit Physical quantities refer to the basic units or to the units set with the Unit command Example SENSe REQuency CENTer Response 118 0 for 118 MHz 3 Boolean values are returned as 0 OFF and 1 ON 4 Character data are returned in short form refer to Structure of a Command Line on page 3 8 Example ROUTe ISELect Response RF Parameters Most commands require the speci
68. User Manual Tektronix DDS200 Digital Demodulation System 070 9952 00 Copyright Tektronix Inc rights reserved Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supercedes that in all previously published material Specifications and price change privileges reserved Printed in the U S A Tektronix Inc P O Box 1000 Wilsonville OR 97070 1000 TEKTRONIX and TEK are registered trademarks of Tektronix Inc WARRANTY Tektronix warrants that the products that it manufactures and sells will be free from defects in materials and workmanship for a period of one 1 year from the date of shipment If a product proves defective during this warranty period Tektronix at its option either will repair the defective product without charge for parts and labor or will provide a replacement in exchange for the defective product In order to obtain service under this warranty Customer must notify Tektronix of the defect before the expiration of the warranty period and make suitable arrangements for the performance of service Customer shall be responsible for packaging and shipping the defective product to the service center designated by Tektronix with shipping charges prepaid Tektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the Tektronix service center is located Customer shall be respo
69. WEST DIST key is pressed the attenuator in the receiver input is set as follows m With AUTO LOW NOISE selected the input attenuation is reduced by 5 dB below the setting under AUTO This improves the signal to noise ratio of the receiver m With AUTO LOW DIST selected the input attenuation is increased by 5 dB above the setting under AUTO This improves the signal to intermodulation ratio of the receiver m With AUTO LOWEST DIST selected the input attenuation is increased by 10 dB above the setting under AUTO This is only useful if for instance the level in the adjacent channel is considerably higher than that of the signal channel With MANUAL selected the attenuator can be set manually in 5 dB steps from to 55 dB Settings can be made using the up and down cursor keys or by direct entry via the numeric keypad and confirmation with ENTER In the case of direct entry the entered numerals are rounded to a value that can be divided by 5 With the 10 dB PREAMP key a low noise preamplifier can be switched into the signal path to improve the noise figure of the receiver This is useful when low level signals are received The attenuator is correctly set in automatic operation In the AUTO LOW DIST and AUTO LOWEST DIST modes the 10 dB preamplifier cannot be switched on as preamplification of the TV signal in these modes is not useful In this case the label 70 dB PREAMP is in italics DDS200 Digital Demodulation System User Ma
70. accurate symbol rate is not known an automatic search routine can be started To do so set the search range with the aid of the UPPER LOWER SEARCH LIMIT keys the UPPER LIMIT must always be higher than the LOWER LIMIT The search itself is started with START AUTO SEARCH Since up to five minutes is needed to search through the whole range it is advisable to set narrow range limits so that the setting can be made quickly A search run may be stopped any time with the STOP AUTO SEARCH key In this case the previous manually set values will be used again After the symbol rate of the modulator has been changed a new search run must be started since the search is only performed once Information on the progress of the search is displayed in the SYMBOL RATE VALUE field where the current symbol rate is indicated at regular intervals approximately every five seconds Once the instrument has synchronized to the symbol rate no search is started when the START AUTO SEARCH key is pressed even if the set search range limits are outside the actual symbol rate NOTE If the automatic symbol rate search is active setting commands other than the STOP AUTO SEARCH command cannot be processed Order of QAM The order of QAM is determined in the modulator and must be set accordingly in the QAM receiver All common methods 4 16 32 64 128 and 256QAM are available and can be selected by means of the ORDER OF QAM key toggle function
71. ail A MICROPROCESSOR 0 BATTERY CHECK OK FAILURE B CONVERTER selftest messages of the converter 1 POWER SUPPLY OK FAILURE 2 SYNTHESIZER PLL OK FAILURE 3 SAW TEMPERATURE OK FAILURE 4 5V REFERENCE OK FAILURE 5 33 24V REFERENCE OK FAILURE 6 TUNER TEMPERATURE OK FAILURE C QAM DEMODULATOR selftest messages of the QAM demodulator QD 8 POWER SUPPLY OK FAILURE 9 OSCILLATOR LVL OK FAILURE 10 AGC OK OUT OF RANGE 11 NOISE AGC OK OUT OF RANGE 12 DIG AGC OK OUT OF RANGE 13 TEMPERATURE OK FAILURE 14 SYMBOL CLOCK OK UNLOCKED 15 EQUALIZER SYNC OK UNLOCKED 16 CARRIER SYNC OK UNLOCKED 17 FRAME SYNC OK UNLOCKED 18 I2C EEPROM OK FAILURE 19 I2C BUS OK FAILURE 20 28MHZ CLOCK OK FAILURE 21 I2C DEMODULATOR OK FAILURE Error Messages The EFA Q continuously checks the main operating parameters If one of these parameters fails or is detected as faulty an error message is displayed in the bottom line of the screen This error message is derived from the self test the messages being positioned in the following scheme according to their number An error causes a 1 to be entered into the corresponding error number if there is no error 0 will be entered Only the messages marked by are used for the selftest error code DDS200 Digital Demodulation System User Manual 4 3 Maintenance and Troubleshooting Table 4 1 Assignment
72. ambient temperature and viewing angle DDS200 Digital Demodulation System User Manual Preparation for Use Table 1 1 Legend for front view Cont Controls Connectors Description TL STATE SIGNAL Indicates thatthe input signal is absent ortoo weak SIGNAL SYNC Signals synchronization problems sc AUDIO Forfuture use REM Signals that the unitis remote controlled RM LLO Indicates IEC IEEE bus local lockout uo Q s SRQ Indicates IEC IEEE bus service request MAIN FUNCTION following hard keys display corresponding menus when pressed MAIN FUNCTION MODE MEASURE MODE MEASURE INPUT SETUP INPUT uu SETUP BE RF SPEC FUNC STATUS C ALARW STATUS LED lights when a special function is selected LED lights when there is an alarm M VARIATION Cursor keys Used to modify data entries step by step VARATION f cl ESC key Displays the previously selected menu or PU submenu each time itis pressed i CLR key Clears an entry to allow the correction of entered F data ENT key Terminates the data entry when pressed ESC CLR ENT Tor DATA The DATA group consists of a keyboard for numeric data input The n function and effect depend on the menu selected The entry is terminated with the ENT key 4 5 6 ERENER f EN m t J D
73. and column the table shows an overview of the commands and their hierarchical relationships see indentations DDS200 Digital Demodulation System User Manual 3 11 Remote Control Common Commands 3 12 m Parameter In the parameter column the required parameters and their range of values are stated m Unit The unit column shows the basic unit of the physical parameters Indentations The various levels of the SCPI command hierarchy are shown in the table by indentations to the right The lower the level the greater the indentation to the right It should be noted that the complete notation of the command includes the higher levels too In the individual command description the hierarchy is represented accordingly This means that for each command all keywords above up to the left most position have to be considered too Upper lower case Uppercase lowercase characters are used to differentiate between the long form and the short form of the keywords of a command in the command description refer to Command Structure on page 3 5 The instrument does not differentiate between uppercase and lowercase characters Special characters A vertical bar in the notation of the parameters is used to separate alternative options and is to be understood as an The effect of the command differs according to the parameter stated Keywords in square brackets may be omitted in compound headers refer to Optional keywords
74. approximately 1 s is obtained For calculation of the parameters there are limit values that are listed in Table 2 5 The limits result from the quantization of the measured I Q values and from the location of the decision fields their distance from the center point For each limit value specified all other interfering quantities are assumed to be Zero 2 T3 Manual Operation Table 2 5 Theoretical maximum and minimum values of calculated parameters for various orders of QAM 4 2544199 90 0 39 1308 315dB 0 1448 361208 460dB 1126 16 37 0908 46008 417 32 1056dB 34 0808 43 008 259 T 46008 185 256 13 34 67 40 370 2346dB 204508 37 3608 46008 086 A With slight noise present the signal SNR 45 dB a limit value of 70 dB is obtained Modulation Error Vector Error The modulation error is the combination of all interfering quantities that occur The modulation error is a calculated quantity indicating the mean or maximum deviation of the I Q values from ideal signal states and thus provides a measure of signal quality The modulation error is specified as RMS and as peak value To calculate the modulation error all decision fields are investigated one after the other To obtain the peak modulation error the maximum magnitude of the difference vector error vector formed by the vectors of the ideal and the actual signal status is determined for each decision field From the maxi
75. apter for a 19 inch rack with handles Power Cord Options If you do not specify a power cord option the demodulator is shipped with a North American 125V power cord The following power cord options are available when purchasing your DDS200 Digital Demodulation System m Option Al Power Universal Europe 220 V 16 A Locking Power Cord 161 0066 09 m Option A2 Power United Kingdom 240 V 15 A Power Cord 161 0066 10 m Option Power Australia 240 V 10 A Power Cord 161 0066 11 DDS200 Digital Demodulation System User Manual Preparation for Use Optional Accessories The DDS200 Digital Demodulation System has a number of optional accessories that you can order to customize your instrument for your application Installation Service Manual 2068 0950 22 03 75 Q male type N to female type BNC adapter 103 0045 00 42 in RF cable 75 Q 012 0159 00 72 in RF cable 75 Q 012 0159 01 42 in RF cable 50 BNC BNC 012 0057 01 72 in RF cable 50 BNC BNC 012 0113 00 Rackmount adapter w handles for a 19 in rack ZZA93 Rackmount adapter w o handles for a 19 in rack ZZA931 Option A4 Power North America 250 V 10 A Power Cord 161 0066 12 Option A5 Power Swiss 240 V 6 A Power Cord 161 0154 00 The following section describes how to prepare the DDS200 for operation i CAUTION To prevent damage to the instrument make sure that the following conditions are true prior to operat
76. ar view Cont Connectors Description DATA PARAE X31 This connector is MPEG transport stream parallel output TS PARALLEL BE 502 Q X21 This connector location is for future use RF 50 Q DEMOD X21 590 X22 RF 50 This connector location is for future use RECEIVER ARETE X32 CENTRON This connector is a PC compatible parallel printr interface ICS X33 RS 232 This connector is a serial remote control interface itis also used to EYE update firmware 34 USER This connector location is for future use PORT DDS200 Digital Demodulation System User Manual 1 7 Preparation for Use Unpacking the Unit Accessories Standard Accessories Options 1 8 After removing the DDS200 Digital Demodulation System from the package check it carefully for mechanical damage If you find any damage immediately contact the forwarding company concerned In such a case keep the cardboard box packing material and shipping documentation The DDS200 Digital Demodulation System is shipped with several standard accessories These accessories and any optional accessories are described below The following accessories are included with this product m User Manual this manual 070 9952 00 Power cord North America 161 0066 00 m Fuse 0099 6729 00 The following options are orderable when you purchase the DDS200 Digital Demodulation System m Option IR Rackmount ad
77. are shown in the instrument manual in square brackets For compatibility with the SCPI standard the instrument must be able to recognize the full command length Some of the commands become considerably shorter when the optional keywords are omitted Example READ POWer RATio VISion SOUNdl This command queries the vision sound1 power ratio measured by the DDS200 The following command has the same effect READ VISion SOUNdl NOTE An optional keyword may not be omitted if its effect is specified in more detail by a numeric suffix m Long and short form The keywords have a long and a short form The keyword may be entered in short or in long form other abbreviations are not allowed Example READ VISion SOUNd1 READ VIS SOUN1 NOTE The short form uses uppercase characters the long form gives the whole keyword Uppercase and lowercase letters are only used for identification in the instrument manual the instrument does not differentiate between the two types of characters m Parameter The parameter must be separated from the header by a white space If a command contains several parameters these must be separated by a comma Some of the queries allow the specification of the parameter DEFault For a description of the various types of parameter refer to Parameters on page 3 9 Example READ FM DEViation Soundl Response 50 000 kHz This query returns the FM frequency deviation for the left
78. at cable connected to the rear panel Disassembling and opening the processor board m Disconnect the flat cable m Release the locking bracket on the right of the processor assembly using a Phillips screwdriver m Pull the processor board to the rear m Open the upper shield cover of the processor board using a Phillips screwdriver m The battery is located on the left front near the large multi way connector To install the battery properly solder its terminal lugs and fix it by means of cable ties Make sure to get the polarities right Polarity is indicated with and on the battery and also on the processor board The symbols on the battery have to match with those on the processor board On power up all assemblies are coarsely checked for their presence and their operation power up screen mask If a failure is detected it will be signaled on power up It is therefore necessary to observe the power up sequence DDS200 Digital Demodulation System User Manual Maintenance and Troubleshooting Self Test QAM The results of the continuously running selftest can be directly queried Press the PRESET key then the SERVICE key appearing on the screen and finally the SELFTEST key By pressing the UP or DOWN key the screen can be scrolled to read the information about the individual module states If in the MODE menu the QAM DEMODULATOR module has been selected the following parame ters will be checked in det
79. ations This section contains the specifications for the DDS200 Digital Demodulation System specifications are guaranteed unless labeled typical Typical specifications are provided for your convenience and are not guaranteed Specifications labeled with the symbol are checked in the Performance Test PT procedure in the service manual NOTE Performance requirements are valid provided that the instruments are operating within environmental parameters and have warmed up for at least one hour Table 1 Electrical Specifications Characteristics Requirements Supplemental information Overvoltage category CAT RF Input Connector front panel female type BNC L Frequency range 47 to 862 MHz Level 100 uV to 700 mV Accuracy typical 3dB Impedance typical 750 L Return loss 12dB Channel bandwidth typical 8 MHz IF Input Level typical 10 to 100 mV 80 to 100 dBuV Impedance typical 500 L Return loss 33 to 40 MHz 20 dB IF Output Level typical 45 mV 93 dBuV Impedance typical 500 Frequency typical 36 MHz Demodulator Modulation modes 4 16 32 64 128 256 QAM Pulse response roll off factors 0 20 0 25 1 Operation at 4 128 and 256 QAM is not specified DDS200 Digital Demodulation System User Manual A 1 Appendix A Specifications Table A 1 Electrical Specifications cont Characteristics Requirements Supplemental information Insertion loss 64 QAM
80. bandwidth LOOP BWIDth HI MED 10 See page 2 34 SENSe QAM LOOP BWIDth SENSe QAM ON OFF Setting the QAM Reed Solomon RS Decoder ON OFF SENSe QAM See page 2 34 RSDecoder SENSe QAM MPEG 188 204 Selecting whether the MPEG SENSe QAM MPEG 2 188 204 usd Mp uad protection bytes See page 2 30 SENSe QAM ON OFF Validation of the error indication bit ERRor INDication 110 ne NEES SENSe QAM See page 2 34 ERRor INDication SENSe QAM NORMal INVerted AUTO Exchange of the 1 0 data stream IQ INVersion NORM INV AUTO D SENSe QAM IQ INVersion SENSe QAM ON OFF MPEG PLL 1 0 SENSe QAM MPEG PLL D 10 DDS200 Digital Demodulation System User Manual Appendix D List of Commands MEMory Subsystem Table D 7 MEMory Commands Command Data Reply data Meaning MEMory F REQuency ddd TTTTTTTT Storing the RF frequency STO 0 to 99 with text 8 characters upper case letters or numbers MEMory F REQuency ddd Calling a stored RF frequency 0 to RCL ii UNIT Subsystem Table D 8 UNIT Commands Command Data Reply data Meaning UNIT LE Vel DBPW DBM DBUV MV l Selection of level unit POWer DBPW DBM DBUV MV See page 2 19 UNIT LE Vel Query of level unit POWer DDS200 Digital Demodulation System User Manual D 11 Appendix D List of Commands READ Subsystem Table D 9 READ Commands Command READ RF LEVel READ FREQuency Reply data dd
81. bove phase jitter is a statistical quantity that affects the I and the Q path equally In the constellation diagram phase jitter shows by the signal states being rotated about their coordinate origin see Figure 2 53 DDS200 Digital Demodulation System User Manual 2 67 Manual Operation 2 68 Constellation diagram 64 QAM Cos 15 41 7MB s Options 14 Quadraturphase Inphase Figure 2 53 Constellation diagram of 64QAM signal with phase jitter PJgys 1 73 Explanation of Calculated Parameters Formulas and Limit Values The constella tion diagram of a demodulated QAM signal is an excellent tool also for a quantitative assessment of the above named transmission parameters allowing fast and accurate conclusions to be drawn about interference in transmission The constellation diagram as a graphical tool for the qualitative assessment of a signal is described in Application and Interpretation of Constellation Diagram on page 2 62 This subsection deals with some basic algorithms that the instrument uses to provide a quantitative assessment of the parameters named above The calculations are based on the I Q values that make up the constella tion diagram m Amplitude Imbalance The amplitude imbalance AI can be determined by two dimensional averaging for all points of a decision field By evaluating the center points thus formed separately for the I and Q components the distances between
82. channel sound 1 DDS200 Digital Demodulation System User Manual 3 7 Remote Control Structure of a Command 3 8 Line m Numeric suffix If an instrument has several identical functions or features for example inputs the desired function can be selected by a suffix to the command Commands given without suffix are interpreted as having suffix 1 The suffix is appended without a space Example SENSe SOUNd SQUelchl ON This command switches on the squelch for sound 1 A command line may contain one or more commands It is terminated by a New Line a New Line with EOI or an EOI together with the last data byte QuickBASIC automatically generates an EOI together with the last data byte Multiple commands in a command line are separated by a semicolon If the next command belongs to a different command system the semicolon is followed by a colon Example CALL IBWRT efa ROUTe ISELect IF AUDio SPEaker ON This command line contains two commands The first command belongs to the ROUTe system The second command belongs to the AUDio system and turns on the loudspeaker If the successive commands belong to the same system and have one or more common levels the command line may be shortened The second command following the semicolon then starts at the level that is below the common levels see also Figure 3 1 The colon after the semicolon must be omitted Example CALL IBWRT efa AUDio MODE AUTO A
83. cting the Unit to the AC Supply Replacing Es s ox LOQUO es eR e rest d Ru A e ie RR EUR S EMC Protective Measures 000s cece eee ee hn Powering On isa e o e ays Re Ria aie ees n a Ru As RR ees Setting the Contrast of the Display Installing Firmware 5 24 35 ach Sq Ee Ru e Pes o qp A e sete nae RR AE UR Connecting Input and Output Signal Battery Backed Memory 0 0 cece rhe Functional Test 7i cec qu ph em Co A PPAR SR CRUS aides Installing Options Installing a printer ae cennetten ye eneee n n IRR Serial Interface E res pg eee te e ANA aN IEC IEEE Bus Connector Manual Operation Sample Setting 0 ER esa veia ta eR Powering on the Unit 2 0 ccc ete Using the main menu MODE hard key Selecting the ERE NR EAE esa ERN viet d Using the main menu INPUT hard key Selecting the Input 5 4 ees 6 era ERE oe ee Setting the RF Frequency 0 cee cece eens Basic Operation 1 6 02056 cece pee rete a bina Rr tures Overview eR COQUE BEER ER e ERE Rx nar al Roble DE D Bro RA qd Display 4 ses Soa ete tu an on Rice wae RR Coe LER Pec ie a eink REFER RA B
84. d RCL requires the specification of a number 150 String data error The command contains invalid string data 151 Invalid string data The command contains invalid string data Example an END message was received before the terminal quote character 158 String data not allowed The command contains a legal character string at a position where it is not allowed Example character data in quotation marks 160 Block data error The command contains invalid block data 161 Invalid block data The command contains invalid block data Example an END message was received before the expected number of data was received 168 Block data not allowed The command contains legal block data at a position where they are not allowed Example 170 Expression error The command contains an invalid mathematical expression Example DDS200 Digital Demodulation System User Manual C 3 Appendix C List of Error Messages Table C 2 Command errors Cont Error Test displayed upon an error queue query number Explanations 171 Invalid expression The command contains an invalid mathematical expression Example the expression contains unmatched parentheses 178 Expression data not allowed The command contains a mathematical expression ata position where it is not allowed Example 180 Macro error An invalid macro was defined or an error occurred druing the excution of the command 181 Invalid outside macro
85. d for the printout selected with LAST LINES When the PRINT key is pressed the alarm messages associated with the selected line numbers are printed If the start line number is higher than the stop line number an error message is output An exception is if there are exactly 1000 entries in the alarm register printing can be continued beyond line 000 Example START LINE 995 STOP LINE 005 PRINT 11 lines from 995 to 005 are printed started printing procedure can be aborted with the ABORT key Clearing the Register The alarm register of the DDS200 is automatically cleared when one of the following conditions occurs The supply voltage is switched on m The RF is changed Another input or input filter SAW filter is selected m A new QAM order or symbol rate is selected m The equalizer setting or the loop bandwidth is changed m MPEG data outputs are newly configured m The constellation diagram or the parameter calculation is activated m The external BER measurement is disabled m The PRESET key is pressed The register can also be manually cleared This is done by pressing first the ALARM function key and then the REG CLR Register Clear soft key The instruments queries whether the register should really be cleared When YES is pressed the register is cleared completely and date and time of the clearing are entered in line 0 of the register The register is now ready for entering new alarm messages
86. d air Do not open the internal shield covers since the risk of breaking a component during cleaning is high and an enclosed assembly will not be soiled that much The inlet and outlet vents are the most affected by dirt The unit can be stored at temperatures between 40 and 70 C If stored for a longer period the unit should be protected against dust DDS200 Digital Demodulation System User Manual 4 1 Maintenance and Troubleshooting Replacing the Battery A A Troubleshooting 4 2 WARNING To prevent injury avoid short circuiting or charging the battery Short circuiting the battery can cause the battery to explode Do not open discharged batteries dispose of batteries as hazardous waste The instrument has a lithium battery for storing the selected status and for operation of the real time clock The battery has a lifetime of approximately five years and should be replaced as required for example after a long storage period at high temperature Replace the discharged battery with one of the same type WARNING Disconnect the power cord from the rear panel of the DDS200 before opening the instrument Failure to do so could expose you to risk of injury or even death The battery is located on the processor board With the unit open that is after folding down the rear panel the processor board is located at the bottom right as viewed from the rear panel the processor board can be recognized by the fl
87. d d Unitas UNIT LEV POW ddd d Hz Meaning Query of the RF level measured value QAM Center frequency RF CARRier READ FREQuency ddd d Hz Query of the carrier frequency RF OFFSet x ote 0 0 50 0 kHz of QAM See page 2 46 READ LEVel IF ddd d PCT Query ofthe IF level READ SIGNal RF NORF UND OVER OK Query if RF signal is applied See page 2 11 READ QAM BERate READ QAM FRAMe LOCKed READ QAM CLOCK LOCKed READ QAM CARRier LOCKed READ QAM SRATe READ QAM EAQualizer LOCKed READ QAM IMResponse Dataare sent without unit D 12 d d E d 110 110 110 dd dd MSPS 110 110 Query of the bit error rate with QAM See page 2 31 Query whether MPEG frame sync word has been found See page 2 46 Query whether symbol clock recovery has locked See page 2 46 Query whether carrier recovery has locked See page 2 46 Query of the symbol rate with QAM See page 2 31 Query if the equalizer is locked with QAM locked unlocked See page 2 31 Query of the receive position with QAM inverted not inverted See page 2 31 DDS200 Digital Demodulation System User Manual Appendix D List of Commands Table D 9 READ Commands Cont Command Data READ QAM EFF PEAK DB MER Reply data dd d PCT db Meaning Query of the effective maximum vector err
88. d for the BER value displayed the second figure indicates the total number of samples to be achieved for example BER 7 2E 9 144 1000 With a typical DVB symbol rate of 6 9 Msps and 64QAM modulation the bit rate is 41 4 Mbit s corresponding to 25367 6 frames per second If the bit errors of 6127 frames are represented by one sample a time of 241 5 ms per sample is obtained At the maximum integration level 1000 samples a measurement thus takes 241 5 s In this case a resolution of 0 1E 9 can be achieved for the BER value DDS200 Digital Demodulation System User Manual 2 79 Manual Operation 2 80 BER Measurement with External Equipment The DDS200 has an internal BER measurement function which does not require any interruption of the program since the error control mechanisms of the DVB signal are used for calculating the BER refer to Selection of Integration Time for BER Measurementpage on page 2 79 This method has its limitations when very high bit error rates are involved 210 5 For measuring high bit error rates or for checking the internal BER measurement function the setup shown in Figure 2 60 can be used Device under test 2715 Spectrum analyzer Noise generator Y uA DDS200 X6 X5 IN QAM modulator OUT DVT 200 Serial data BER measurement unit Figure 2 60 Setup for external BER measurement Equipment
89. dard is based on the IEEE 488 2 standard and its goal is a standardization of the device specific commands error handling and status registers refer to Structure and Syntax of Device Dependent Messages on page 3 5 Basic knowledge of IEC IEEE bus programming and operation of the controller is required for a clear understanding of this chapter A description of the interface commands can be found in the relevant manuals The effects of the SCPI requirements on the command syntax error handling and configuration of the status registers are described in detail in the relevant subsections Tables provide a quick overview of the commands implemented in the instrument and the assignment of the bits in the status registers The tables are supplemented by a detailed description of commands and status registers Detailed program examples for all essential functions are given in Appendix E Program Examples All program examples are written in QuickBASIC The following brief operating instructions allow the instrument to be quickly put into operation and to set the basic functions It is assumed that the IEC IEEE bus address which is set at the factory to 6 has not been changed 1 Connect DDS200 and controller using the IEC IEEE bus cable 2 Generate and start the following program on the controller INCLUDE c qbasic qbdecl bas Insert driver CALL IBFIND DEV1 efa Open channel to device CALL IBPAD efa 6 Send device addr
90. definition A wild card character for a macro element is outside of the macro definition Example 183 Invalid inside macro definition The macro definition contains a syntax error Example 184 Macro parameter error A command within the macro definition had the invalid number or the wrong element type Example Execution Errors cause bit 4 in the ESR register to be set Table C 3 Execution errors Error number 200 201 202 210 Test displayed upon an error queue query Explanations Execution error Error occurred in the execution of the command eg no paper in the printer Invalid while in local The command cannot be executed in the device local state because of a control Example the device receives a command which would modify the position of the rotating knob and cannot be executed since the device is in the local state Settings lost due to rtl A setting related to a control gets lost when the device is switched from LOCS to REMS or LWLS to RWLS Trigger error Error on triggering the device DDS200 Digital Demodulation System User Manual Appendix C List of Error Messages Table C 3 Execution errors Cont Error Test displayed upon an error queue query number Explanations 211 Trigger ignored The trigger GET TRG or trigger signal was ignored because of the device time control Example the device was not ready to answer 212 Arm ignored An arming signal was ignored by
91. dress to controller CALL IBTMO efa 13 Sets response time to 10 s REM kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk Initialization of Device IEC IEEE bus Status Register DDS200 settings are brought to a defined status REM kkkkkkkkkkkkkkkkkk kk Initializes device dock ke e de e e e e e e A A x REM InitDevice CALL IBWRT efa CLS Resets Status Register CALL IBWRT efa RST Resets device REM DDS200 Digital Demodulation System User Manual E 1 Appendix E Programming Examples Sending Device Setting Commands In this example the input frequency and RF level control are set REM kkkkkkkkkkkkkkkkkkxk Device setting commands kkkkkkkkkkkkkkkkkkk CALL IBWRT efa SENS FREQ CENT 454 25 RF frequency to 454 25 MHz CALL IBWRT efa INP ATT AUTO ON Attenuator control automatic REM kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk Switchover to Manual Control REM Switches device to manual control xxxex CALL IBLOC efa Sets device to local REM kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk Readout of Device Settings List Management The settings of example 3 are read out using commands in short form REM kkkkkkkkkkkkk Reads out device settings kkkkkkkkkkkkkkk FRequenz S
92. e Gaussian Noise Noise can disturb the digitally modulated signal during analog transmission Additive superimposed noise normally has a constant power density and a Gaussian amplitude distribution throughout the bandwidth of a channel If no other error is present at the same time the points representing the ideal signal status are expanded to form circular clouds See Figure 2 52 2 66 DDS200 Digital Demodulation System User Manual Manual Operation Constellation diagram 64 QAM Cos 15 41 7MB s Options Quadraturphase Ene ese Inphase Figure 2 52 Constellation diagram of 64QAM signal with additive noise SNR 30 0 dB When interpreting the constellation diagram in Figure 2 52 note that a similar diagram may also be obtained for other types of interference so that a distinction from noise produced patterns cannot be made The following are types of interference that can cause constellation diagrams similar to Figure 2 52 m Impulsive noise Nonlinearities in amplifiers m Intermodulation m Errors from uncompensated echoes and non flat frequency response m Phase Jitter Phase jitter or phase noise in the QAM signal is caused by frequency translators in the transmission path or by the I Q modulator It may also be produced in carrier recovery but this effect is small in the DDS200 demodulator and is ignored here In contrast to the phase error described a
93. e Register in decimal form Bit 6 is always 0 READ STATUS BYTE QUERY outputs the contents of the status byte in decimal form SELF TEST QUERY causes all selftests of the device and outputs an error code in hexadecimal form WAIT to CONTINUE allows processing of commands only after all preceding commands have been executed and all signals are settled see also OPC 3 15 Remote Control Instrument Model and Command Processing Input Unit Command Identification 3 16 The instrument model shown in Figure 3 2 is configured under the aspect of processing IEC IEEE bus commands The individual components operate independently of each other and simultaneously They communicate with each other by means of messages Input unit with IEC EEE Bus input buffer Command identification Data set Status reporting System Device hardware IEC IEEE Bus Onput unit with onput buffer Figure 3 2 Instrument model with remote control via IEC IEEE bus The input unit receives the commands in the form of characters from the IEC IEEE bus and collects them in the input buffer The input buffer has a capacity of 1024 characters The input unit sends a message to the command identification as soon as the input buffer is full or as soon as it receives a terminator lt PROGRAM MESSAGE TERMINATOR as defined by IEEE 488 2 or the interface message DCL If the input buffer is full the data transfer from the IEC IEEE bus is sto
94. e key characteristics are Transmission rate fixed 270 Mbit s Source impedance 75 unbalanced BNC DC component OV Signal amplitude 0 08 V to 0 8 V into 75 Q Length of transmission link Depends on cable type cable attenuation must not exceed 12 dB at 70 MHz Simultaneous display of constellation and MPEG output Two DDS200s can be coupled via an IF connection to allow the simultaneous generation of a constella tion diagram and MPEG 2 output For this the following setup can be used DDS200 No 1 DDS200 No 2 Connection IF output IF input Figure 2 66 Cascading of two DDS200s The two units can be connected as shown in Table 2 9 Table 2 9 Cascading of two DDS200s DDS200 No 1 Application DDS200 No 2 Application MPEG data or constellation X11 IF output X10 IF input MPEG data or constellation diagram diagram MPEG data XT SER MPEG DATA OUT MPEG data 2 88 DDS200 Digital Demodulation System User Manual Remote Control Brief Instructions NOTE Appendix D List of Commands contains a complete list of commands for the DDS200 Digital Demodulation System The standard DDS200 Digital Demodulation System has an IEC IEEE bus interface that complies with the IEC 625 1 IEEE 488 2 standard The connector is located on the rear panel A controller can be connected for remote control The DDS200 supports the Standard Commands for Programmable Instruments SCPI version 1993 0 The SCPI stan
95. e takes approximately 250 ms If GATE CNT 1 has been selected a new cycle with new I Q values is started when a cycle is completed independent of the previous values and is then displayed With GATE CNT 3 selected a collected I Q value remains in the display over 3 complete cycles During this time new cycles are started the measured data of which are again displayed for 3 cycles This display is still being updated although the integration time is now three times as long as before The setting range for GATE CNT is 1 to 99999 A special function is offered by the MAX HOLD key In this case the GATE TIME is set to 1000 ms and the value of GATE CNT is set to infinite Using this function long term monitoring can be performed since displayed I Q values are only cleared when the function is terminated With the aid of the FREEZE key the currently displayed constellation diagram can be frozen This function is useful when a particular event should be retained on the screen for printing DDS200 Digital Demodulation System User Manual 2 53 Manual Operation 2 54 QAM Parameters When the QAM PARAMETERS key is pressed the DDS200 is switched to parameter calculation The parameters selectable in the constellation analyzer mode are now preset and can no longer be varied GATE TIME 750 ms GATE CNT 1 During the set gate time of 750 ms approximately 840 000 I Q values are stored in the internal data memory and used for stati
96. eading the register does not change its contents Summary bit As stated above the summary bit for each register is derived from the EVENt and the ENABle registers The result is entered into a bit of the CONDition register of the next higher register The instrument automatically generates the summary bit for each register An event such as a non locking PLL may thus cause a service request through all hierarchical levels NOTE The Service Request Enable Register SRE defined in IEEE 488 2 may be considered as the ENABle register of the STB provided that the STB is confi gured in conformance with SCPI Accordingly the ESE may be considered as the ENABle register of the ESR DDS200 Digital Demodulation System User Manual 3 21 Remote Control Overview of Status Registers amp 15 not used amp 14 free amp 13 free amp 12 free amp 11 free amp 10 free amp 9 free amp 8 free amp 7 free amp 6 free amp 5 free amp 4 free amp 3 free amp 2 free SRQ amp 1 free amp 0 free amp 7 4 STATus OPERation register 67 RQS MSS amp 57 ESB 4r MAV E 3 amp 2 li 1 amp 15 not used 0 amp 14 free amp 13 free SRE STB amp 10 free amp 9 free
97. ear panel Several jumpers are provided in front of the flat cable The one at the right is normally in position 1 2 To release an initial firmware update change this jumper into position 2 3 right and switch on the unit If the flashup software is started on the PC the firmware is loaded into the unit even if the unit has no executable firmware At the end set the jumper to position 1 2 and close the unit Firmware in modules Most modules options are provided with a certain amount of firmware in OTPs similar to EPROMs but not ultraviolet erasable that must be replaced only in rare cases If however replacement is necessary installation instructions are supplied with the new OTP Basically an OTP is replaced on a module as follows 1 Loosen the rear panel as described in Installing Options on page 1 16 and fold it down Loosen all connections between the rear panel and module concerned Remove the module from the rear Remove the upper cover from the module UU wc Remove the OTP using an appropriate tool For the position of the OTP refer to the instructions that are packaged with the OTP e Insert the new OTP 7 Re assemble the parts in reverse order 8 Observe if there are any messages displayed when powering on the unit DDS200 Digital Demodulation System User Manual Preparation for Use Connecting Input and Output Signal Battery Backed Memory Functional Test Apply an RF signal 4
98. ed bit by bit with the STB under consideration of bit 6 The result is ORed and is then returned possibly inverted as a reply to a parallel poll of the controller The result can also be read out without parallel poll by the query IST First the device must be set for the parallel poll by the QuickBASIC command IBPPC This command assigns a data line to the device and determines whether the reply has to be inverted The parallel poll itself is made by IBRPPO The parallel poll mode is mainly used to find out quickly which of the many devices connected to the IEC IEEE bus has caused a SRQ Fot thisSRE and PPE must be set to the same value Queries Each individual register of a status register can be read out by queries The individual queries are given in the detailed description of the registers on page 3 23 The queries always return a number representing the bit pattern of the queried register This number is evaluated by the controller program Queries are mainly used after a SRQ to obtain detailed information on the cause for the SRQ Error Queue Query Each error condition in the instrument causes an entry in the error queue The entries in the error queue are detailed error messages in plain text which can be read out via manual control in the ERROR menu or via IEC IEEE bus by the query SYSTem ERRor Each query SYSTem ERRor returns an entry from the error queue If there are no more error messages in the error queue 0 No er
99. ed on approximately 1 000 000 symbols the time characteristic of the QAM signal and the information regarding any superimposed noise is lost Moreover there is no information as to what symbols were incorrectly demodulated It is therefore not possible to evaluate impulse noise separately from Gausian noise Nonlinearities Nonlinearities of amplifiers cause amplitude and phase of amplifiers distortion of modulated signals Since linear QAM modulation is employed mainly in cable systems where signal levels are relatively low feedback amplifiers can be used These amplifiers are sufficiently linear so that the effect on the QAM signal is negligibly small 2 76 DDS200 Digital Demodulation System User Manual Manual Operation Intermodulation For multichannel cable transmission much greater demands are made on amplifier linearity Intermodula tion between adjacent channels is critical especially with higher order QAM modulation It is second and third order nonlinearities that are of practical relevance For example intermodulation on a DVB channel Cy with a carrier frequency of Wy WN 001 002 is obtained for the channel configuration shown in Figure 2 58 Amplitude MN 02 W1 a N r 7 0 On 02 01 w t01 p Intermodulation of C1 Further intermodulation and C3 in channel Cy of C1 and C Figure 2 58 Intermodulation due to 2nd order nonlinearities 3
100. ed state is reached This mechanism can be used for synchronization of the command processing IEC IEEE bus queries cause the data set management to send the desired data to the output unit Status Reporting System The status reporting system collects information about the device status and makes it available to the output unit on request Structure and function are described in detail in Status Reporting System on page 3 19 DDS200 Digital Demodulation System User Manual 3 17 Remote Control Output Unit The output unit collects the information requested by the controller from the data set management It processes the information in conformance with the SCPI rules and makes it available in the output buffer The output buffer has a capacity of 1024 characters If the requested information is longer it will be made available in portions in a way that is not noticeable to the controller If the device is addressed as a talker and the output buffer does not contain any data or expect data from the data set management the output unit sends the error message Query UNTERMINATED to the status reporting system No data will be sent on the IEC IEEE bus and the controller will wait for timeout This procedure is prescribed by SCPI The output unit is cleared as soon as the command line has reached the output unit It is written with the new data resulting from this line The output unit is cleared in particular when there is a line between
101. ed using the PRINTER TYPE soft key The following types of printer are supported EPSON COMP HP COMP For all Epson RX80 compatible printers For all HP compatible printers including Deskj et and Laser et Forthe ink jet printer PUD3 from Rohde amp Schwarz R amp S PUD COMP With the FORMFEED soft key it is possible to select whether an automatic form feed should take place or not after a print out Level Units Menu The unit for level indication is selected in this menu see Figure 2 21 SETUP LEYEL UNITS RF RF LEVEL 583 250 nHz 42 7 dBuV dpi Figure 2 21 SETUP LEVEL UNITS menu The measurement display offers five level units dBpW dB referred to the power of 1 pW dBuW dB referred to the power of 1 uW dBm dB referred to the power of 1 mW dBuV dB referred to the voltage of 1 V uV mV direct voltage indication DDS200 Digital Demodulation System User Manual Manual Operation The conversion is as follows Unit Impedance 75 uV 10 10 V mV 1 mV 1000 uV dBuV 0 dBuV 1 uV dBm 0 dBm 2108 8 dB uV dBpw 0 dBpw 18 8 dB uV dB uW X OdBuW 78 8 dB uV Mode Key The mode key is pressed to display the MODE menu see Fig ure 2 22 The basic mode of the unit can be set by pressing the corresponding soft key All modes that can be set are represented in normal characters Whether or not a mode can be set depends on the hardware installed in the unit Modes which are not available a
102. eek oli eds rud 2 30 SPECIAL FUNCTION Menu ea a eee eee ee eee eee eee 2 34 ALARM Menu eur tae rien sat ee BP eee seb 2 38 MEASURE Menu 45 5 orbe SNC NP Sea E SR 2 46 Preset Values and Menu Overview 2 58 Examples of Application 0 0 eee ec cece eee 2 62 Brief lnstr ctions ress ie ossa ive E o RI EROR SE E tik Y oe 3 1 Switching to Remote Control 3 2 Setting the Device Address 3 2 Displays in Remote Control 8 55 3 2 Return to Manual Control 3 3 IEC IEEE Bus 3 4 Interface Messages oc eese eee Reh ha nee 3 4 Device Dependent Messages Commands and 3 4 Structure and Syntax of Device Dependent Messages 3 5 SCPI Introduction eee eR ES ei SSE ADGA ASA SR CREER AUR 3 5 Command Structure llle 3 5 Structure of Command Line 3 8 Responses to Queries 2 0 Ih 3 9 Parameters bcm eed cep Ee EE Pelr re Rire repe 3 9 Overview of Syntax Elements 3 11 Description of Commands 3 11 Notation e rb RECIPI aC P n P ERE 3 11 Common Commands 0 cece cece hne 3 12 Ins
103. eparation for Use Table 1 2 Legend for rear view Cont Connectors Description SER QAM SEE MPEG DATA ASI X5 to X8 OOOO X5 QAM serial data output 75 X6 QAM serial clock output 75 Q X1 MPEG transport stream serial output 75 X8 This connector location is for future use X9 to X12 X9 RF input 75 O Option 750 IF50Q IF 500 ZERO REF O Note The instrument can have only one RF input The RF OOOO connector is located either on the front panel or the rear aM panel The customer selects the location of the connector X10 IF input 50 200 mVpp IF output 50 200 mVpp X12 This connector location is for future use X13 to X20 These connector locations are for future use TD NAM ATA CARR N AUDIO A X23 to X26 These connector locations are for future use mE AUDIO A AUDIO B picis 1 L 2 R AUDI X27 AUDIO This connector location is for future use e SERG S X28 SERBUS Internal series data buses Serbus and I2C bus only for maintenance efe and future external extensions EC625 IEEE488 X29 IEC 625 This is the interface connector for the remote control of the unit All device functions can be operated via the IEC IEEE bus All device A ros states can also be queried X30 NICAM This connector location is for future use 1 6 DDS200 Digital Demodulation System User Manual Preparation for Use Table 1 2 Legend for re
104. er PC to enable the remote control of the unit via RS 232 SETUP RENOTE RS232 RF RF LEVEL 363 250 MHz 16 4 dBu 1200 2400 4500 EI BAUDRATE DATABITS PARITY STOPBITS HARDWARE HAHOSHARE Figure 2 19 SETUP REMOTE RS232 menu DDS200 Digital Demodulation System User Manual Manual Operation After pressing one of the five soft keys the associated parameter is directly set BAUDRATE Data transfer rate in bits s DATABITS Number of data bits transferred per byte without parity bit PARITY Check of data transfer by means of the parity bit If NO is selected no check will take place since no parity bit is transferred With EVEN selected even parity is checked With ODD selected odd parity is checked STOPBITS Number of stop bits set during transfer HANDSHAKE With NO selected there is no handshake XON XOFF is set if the additional signal lines RTS CTS DTR are not used and software handshake 15 used If HARD WARE is set these additional lines are used Printer Menu Selecting the Type of Printer The type of printer connected to the Centronics interface X32 can be indicated in this menu see Figure 2 20 SETUP PRINTER RF RF LEVEL 383 250 MHz 19 3 EGET PRINTER EPSOM COMP COMP R amp S PUD COMP TYPE FORMFEEO PRINTER RESET Figure 2 20 SETUP PRINTER menu DDS200 Digital Demodulation System User Manual 2 23 Manual Operation 2 24 The type of printer is select
105. erates a SRQ upon completion of its settings The SRQ is the only way for the instrument to become active on its own A controller program should set the instrument so that a service request will be generated in case of malfunctions The program should suitably respond to the service request A detailed example of a service request routine is given in Appendix D Program Examples Serial Poll Similar to the STB command the serial poll is used to query the status byte register of a device Querying is implemented by interface messages and is therefore much quicker The serial poll method has already been defined in the IEEE 488 1 standard and used to be the only standard method of querying the status byte register This method also works with instruments which neither conform to SCPI nor to IEEE 488 2 DDS200 Digital Demodulation System User Manual Remote Control The QuickBASIC command for the execution of a serial poll is IBRSP Serial poll is mainly used to get a quick overview of the device status of several devices connected to the IEC IEEE bus Parallel Poll In the parallel poll mode up to eight devices are simultaneously requested by a command from the controller to transmit 1 bit of information on the assigned data line ie to pull the assigned data line to logic or 1 Similar to the SRE register which defines the conditions under which a SRQ will be generated there is a Parallel Poll Enable Register PPE which is also AND
106. eration overview 2 8 Battery replacing 4 2 BER calculations 2 48 external equipment 2 80 measurement 2 48 selecting integration time 2 79 BER integration 2 35 Bit Error Rate 2 48 Bus lines description B 1 C Carrier suppression 2 69 Cascading analog and digital two demodulatin systems 2 88 Central coefficient 2 34 Certifications and compliances A 4 Channel equalizer mode 2 34 Cleaning 4 1 Command sequence and synchronization 3 18 Command identification remote control 3 16 Command line structure 3 8 Common commands remote control 3 12 CONFigure commands D 15 Connecting input and output signals 1 15 Constellation diagram 2 50 application 2 62 formulas and limit values 2 68 Gate Time and Gate CNT 2 53 QAM parameters 2 54 DDS200 Digital Demodulation System User Manual Contrast 1 2 setting 1 13 Cursor keys description 2 13 D Data frame size 2 37 Data output MPEG 2 36 Data set 3 17 Date Time menu 2 20 Default settings 2 16 Demodulator QAM 2 26 Device address setting 3 2 Device hardware 3 17 Display overview 2 9 E Echo diagram 2 57 Editing text and numerals 2 15 Equalizer mode 2 34 Error bit 2 37 Error messages descriptions C 1 Examples programming E 1 Examples of Application 2 62 F Factory defaults 2 16 Filter FIR 2 34 SAW 2 31 Firmware in modules 1 14 installing 1 13 Fuses 1 11 replaci
107. eric value by one step m NF NINF INFinity Negative INFinity NINF represent the numeric values 9 9E37 or 9 9E37 INF and NINF are sent as device responses only NAN Not A Number NAN represents the value 9 91E37 NAN is emitted as device response only This value is not defined Possible causes are the divison of zero by zero the subtraction of infinity with infinity and the representation of missing values Boolean parameters Boolean parameters represent two states The ON state true condition is represented by ON or a nonzero numeric value The OFF state false condition is represented by OFF or the value of 0 Queries always return 0 or 1 Example Setting command AUDio SPEaker ON Query AUDio SPEaker Response 1 Character data Character data follow the syntax rules for keywords and have a short and a long form Similar to other parameter they must be separated from the header by a white space A query returns the short form of the character data Setting command AUDio SOURce MPEG Query AUDio SOURce Response MPEG Block data Block data is a format suitable for the transmission of large data volumes command with a block data parameter has the structure shown in the following example DDS200 Digital Demodulation System User Manual Remote Control Example HEADer HEADer 245168XXXXXXXX The ASCII character denotes the beginning of the data block The next number specifies the number of subseque
108. error modulator AI amplitude imbalance modulator CS carrier suppression 2 Deviation from linear phase depends on whether an equalizer is used 3 Deviation from ideal amplitude frequency response depends on whether an equalizer is used 4 The C N ratio only applies if all other conditions are ideal 5 Forthe specified linearity the level drop for a basic signal constellation is specified 6 All values are based on experience calculation and simulation Specified limit values guarantee acceptable reception provided no other types of error occur Valuable information on the definition of parameters calculation methods and interpretation are given in Explanation of Calculated Parameters Formulas and Limit Values on page 2 68 Spectrum Measurement and Echo Display A SPECTRUM and an ECHO PATTERN function are available to help understand the characteristics of your transmission channel Both functions rely on the capability of the instrument to adapt to receiving conditions via the integrated self adapting equalizer The internal equalizer coefficients are accessible in the instrument are mathematically evaluated to create these displays With both functions the calculation is performed only once since reading out the coefficients takes several seconds Another press of the SPECTRUM or ECHO PATTERN key causes the display to be updated DDS200 Digital Demodulation System User Manual 2 55 Manual Operation 2 5
109. errupts processing of received commands and sets the com mand processing software to a defined initial state The device setup remains unchanged IFC IBSIC controller96 Resets the interfaces to their Interface Clear initial condition LLO IBCMD controller Locks the LOC IEC ADDR key Local Lockout CHR 17 DDS200 Digital Demodulation System User Manual B 3 Appendix B IEC IEEE Bus Interface Addressed Commands Table B 3 Common commands Cont Command QuickBASIC command Function in the device SPE IBCMD controller Ready for serial poll Serial Poll Enable CHR 24 SPD IBCMD controller End of serial poll Serial Poll Disable CHR 25 PPU Parallel Poll Unconfigure IBCMD controller CHR 21 End of parallel poll query status The addressed commands are in the code range 00 to OF hex They only affect devices addressed as a listener Table B 4 Addressed commands Command SDC Selected Device Clear GTL Go to Local PPC Parallel Poll Configure QuickBASIC command IBCLR efa IBLOC efa IBPPC efa data Function in the device Interrupts processing of received commands and sets the com mand processing software to a defined initial state The device setup remains unchanged Change to local mode manual control Configure device for parallel poll The QuickBASIC command executes PPE PPD in addition DDS200 Digital Demodulati
110. ers providing valuable information on problems that may occur during transmission In addition the display of constellation diagrams on the LCD can be individually configured and variable result hold times up to co can be set Thus signal events lasting an extended period of time can be displayed Another benefit is the automatic storage of messages in the alarm register This powerful unit can be used any time for applications in development laboratories quality assurance and production monitoring of TV consumer electronics This section presents and describes the different functions in their logical order To take full advantage of the instrument capabilities particular attention should be paid to the characteristics mentioned in Examples of Application on page 2 62 The following discussions of the DDS200 menus provide information about interpreting the measurement results obtained with the DDS200 Overview For users already familiar with basic DDS200 characteristics the steps required for the direct synchronization of a QAM signal are listed below in their sequence 1 Switch on instrument and establish RF IF connection Press PRESET Select input frequency RF and input INPUT Select order of QAM STATUS menu DAD cR cs yp Select symbol rate STATUS SYMBOL RATE menu After the previous selections the calculated parameters or the constellation diagram can be displayed in the MEASURE menu 2 26 DDS200 Digital De
111. ery PRE returns the contents of the Parallel Poll Enable Register in decimal form PSC O11 POWER ON STATUS CLEAR determines whether on power on the contents of the ENABle Register is retained or cleared DDS200 Digital Demodulation System User Manual Remote Control RCL 0 to 9 RST SAV 0 to 9 SRE 0 to 255 STB TST WAI DDS200 Digital Demodulation System User Manual PSC 0 Causes the status register to retain its contents With a corresponding configura tion of the status registers ESE and SRE a Service Request may be asserted at power on PSC 0 Clears the register The query PSC reads out the contents of the power on sta tus clear flags The response may be 0 or 1 RECALL calls the device state which has been stored with the command SAV under the number indicated SAV enables 10 device states 0 to 9 to be stored RESET sets the device to a defined default state This command mainly corresponds to a stroke on the PRESET key The default state is indicated in the description of the command refer to Presetting the Unit on page 2 16 SAVE stores the current device state under the number indicated see also RCL SERVICE REQUEST ENABLE sets the Service Request Enable Register to the defined value Bit 6 MSS mask bit remains 0 This command determines the conditions under which a Service Request will be asserted The query SRE outputs the contents of the Service Request Enabl
112. ess to controller CALL IBTMO efa 12 Response time to 3 sec CALL IBWRT efa RST Reset device CALL IBWRT efa CLS Reset SCPI register CALL IBWRT efa SENSE FREQ CHAN 56 Set RF receive frequency to channel 56 CALL IBWRT efa INP ATT AUTO ON Set RF level control to DDS200 Digital Demodulation System User Manual 3 1 Remote Control automatic mode CALL IBWRT efa AUD SPE OFF Switch off loudspeaker ATtenuation SPACE 10 Provide text variable 10 characters CALL IBWRT efa INP ATT Query position of attenuator CALL IBRD efa ATtenuation Read in value CALL IBWRT efa UNIT LEV POW DBM Level unit dBm PEgel SPACE 10 Provide text variable 10 characters CALL IBWRT efa READ RF LEV Query input level CALL IBRD efa 1 Read in value PRINT Pegel dBm PEgel Output values on PRINT Attenuation Attenuation controller screen 3 Press any key on the front panel to return to manual control Then press the LOCAL softkey Switching to Remote Control Setting the Device Address Displays in Remote Control On power up the DDS200 is always in the manual control mode LOCAL state and can be operated from the front panel Switch over to remote control REMOTE state happens as soon as the DDS200 receives an addressed command from a controller In the remote control mode operation from the front panel is inhibited The DDS200 remains in t
113. essing the soft key next to the corresponding soft key text on the screen Some parameters require additional entries of numerals or text see Editing Text and Numerals on page 2 15 Depending on the menu the settings can be selected in a lower menu level A submenu is displayed by pressing the soft key For example several settings can be directly performed in the INPUT menu Other settings for example in RECEIVER ATTEN are carried out at a lower menu level In this case additional parameters can be set Press the ESC key to display the next higher menu level from a submenu press the corresponding hard key to display to the uppermost menu level DDS200 Digital Demodulation System User Manual Manual Operation Editing Text and Numerals Editing Numerals As described in Numeric Keypad page 2 14 the parameters selected via the numeric keypad can be directly modified To select the parame ters enter the figure and then confirm it by pressing the ENT key on the cursor keypad If a correction is required during entry the figure in front of the cursor can be erased and overwritten by means of the CLR key on the cursor keypad For this purpose the cursor can be shifted with the keys and from the end to the required position Editing Text Text entries for example in the RF STO RF menu under EDIT TEXT are possible using the cursor keys and the soft keys A box with the characters available is shown under the te
114. etter distinction see Figure 2 1 Also refer to Front Panel on page 1 2 for descriptions of the controls Front view of DDS200 59 Tektronix DDS200 Digital Demodulation System STATE MAIN FUNCTIO VARATION SIGNAL MODE MEASUR sync INPUT SETUP SS RM C RCL LLO HARDCOPY esc cur enr z al nO 1L 2R 9 AUDIO O6990 7j 750 20 lt 250 Figure 2 1 Front panel controls The following key information is provided in this section m Sample Setting on page 2 2 provides a sample setup of the unit This setup is intended to quickly familiarize the user with the operation and the basic functions of the DDS200 m Basic Operation on page 2 8 lists the different functional groups on the front panel and provides references to further information about each group This subsection also provides an overview of basic operation m General Device Settings on page 2 19 contains information about settings that are independent of installed hardware or the selected mode Wm Operation as Demodulator for Quadrature Amplitude Modulated QAM Signals on page 2 26 describes the operation of the DDS200 as a QAM demodulator for DVB signals DDS200 Digital Demodulation System User Manual 2 1 Manual Operation Sample Setting Powering on the Unit This sample setting procedure quickly fam
115. f a data byte can be terminated by one or two stop bits 05 06 Or to Xs Start bit Parity v Data bits bit Stop bits Figure F 1 Transmission of character A in 7 bit ASCII code even parity 2 stop bits DDS200 Digital Demodulation System User Manual F 3 Appendix F Remote Control via RS 232 C Interface Interface Functions The interface is controlled by means of several control characters from the ASCII code range 0 to 20 hex These control characters are transmitted via the interface see Table F 2 Table F 2 Control characters of RS 232 Interface Designation REMC char LOKC char SRQ char GET char Control character Ctrl gt 12 hex Ctrl L 0C hex Ctrl B 02 hex Ctrl G 07 hex Function Remote local switchover This character enables switchover between the modes LOCAL and REMOTE Local Lockout S witchover This character enables or disables switchover to the LOCAL state Service Request SRQ This character is sent if bit 6 of the status byte is set Should the character SRQ char be received it will be ignored Group Execute Trigger GET This character is not permitted within a data string and will cause an error message Outside a data string ie after a terminator or after DCL GET char will produce DEVICE TRIGGER DEVICE TRIGGER is not supported DCL char XON char XOFF char END char F 4 Ct
116. fication of a parameter The parameters must be separated from the header by a white space Parameters may be specified as numeric values Boolean parameters character data character strings and block data The type of parameter required for the specific command as well as the permitted range of values are described together with the commands refer to Description of Commands on page 3 11 Numeric values Numeric values may be entered in any customary form using sign decimal point and exponent If the values exceed the resolution of the instrument they will be rounded off The mantissa may comprise up to 255 characters the exponent must be in the range between 32 000 and 32 000 The exponent is denoted by an E The exponent alone must not be used Physical quantities may be stated with the unit Permissible prefixes for the unit are G Giga MA Mega MOHM and MHZ are also allowed K Kilo M Milli U Micro and N Nano If no unit is specified the basic unit will be used DDS200 Digital Demodulation System User Manual 3 9 Remote Control 3 10 Example SENSe FREQuency CENTer 118MHz SENSe FREQuency CENTer 118 Special numeric values The parameters DEFault UP and DOWN are interpreted as special numeric values m DEF DEFault denotes a preset value stored in the EPROM This value coincides with the basic setting called up by the RST command m UP DOWN UP or DOWN increments or decrements the num
117. gital Demodulation System User Manual C 1 Appendix C List of Error Messages Table C 2 Command errors Cont Error number 104 Test displayed upon an error queue query Explanations Data type error Command contains an invalid data element Example numeric data for frequency setting were expected and ON was encountered 105 108 109 110 GET not allowed A Group Execute Trigger G ET was received within a program message Parameter not allowed The command contains too many parameters Example the command SENSe FREQuency allows only one frequency specification Missing parameter The command contains fewer parameters than required Example the command SENSe FREQuency requires a frequency specification Command header error The header of this command contains an error 111 112 113 114 120 121 Header separator error The header contains an illegal separator Example the header is not followed by a white space ESE255 Program mnemonic too long The header contains more than 12 characters Undefined header The header is undefined for this specific device Example XY Z is not defined for any device Header suffix out of range The header contains a numeric suffix which makes the header invalid Example INP ut3 does not exist in the device Numeric data error Command contains a faulty numeric parameter Invalid character in number A numeric contains an
118. gram of 64QAM signal with interferer C I 25 0 dB NOTE When using a self adapting channel equalizer as in the DDS200 Digital Demodulation System a partial compensation of the sinusoidal interference takes place The equalizer must be switched off to enable correct assessment of the interference Carrier Suppression The residual carrier gives rise to a special type of interference whose frequency equals the carrier frequency in the RF channel A residual carrier is superimposed on the QAM signal in the I Q modulator Since the interference and the carrier have the same frequency a DC component is obtained in the baseband The distribution of this DC component to the I and the Q component depends on the phase difference between the residual carrier and the recovered carrier DDS200 Digital Demodulation System User Manual 2 65 Manual Operation The magnitude of the DC component is equal to the radius of a circle that would be obtained in the event of a frequency offset of the interference relative to the carrier signal In the constellation diagram a residual carrier shows up as a shifting of the signal states corresponding to the DC compo nents of the I and Q components See Figure 2 51 Constellation diagram 64 QAM Cos 15 41 7MB s Options 1d Quadraturphase Figure 2 51 Constellation diagram of 64 signal with residual carrier in component CS 17 6 dB W Additiv
119. he 1000 desired measurement results last count have already been collected and stored Of course the BER can be evaluated now but the accuracy is not of optimum value The first value is regularly increased until the last count is reached At this stage a switch over is made to a running BER calculation the last 1000 samples are combined to one measured value so that a new set of values is obtained every 241 55 ms The great advantage of this method is that indicated BER is always the latest value since the measured value is continuously updated The system is flexible enough to immediately reduce the number of integrated samples at a sudden deterioration of the input signal quality such as when a noise generator is connected The running BER calculation can best be explained with an example using 10 as the last count see Figure 2 38 The other counts can be deducted NOTE BER as measured by the DDS200 may be limited by system noise to lt 106 in 256 QAM 2 48 DDS200 Digital Demodulation System User Manual Manual Operation Start of BER measurement Samples n ntl nt n3 n45 n nt 7 nt8 n 9 n0 n 11 12 13 14 n 15 Ist measured value Cc 2nd measured value 3rd measured value 4th measured value c 5th measured value M 6th measured value M Thh measured value M 3 th measured value LLL 9th measured value 5 10th measured value EM J th
120. he REMOTE state until it is switched back to the manual control mode either from the front panel or via the IEC IEEE bus see Return to Manual Control page 3 3 Switch over from the manual mode to remote control and vice versa has no effect on the instrument settings The factory set IEC IEEE bus address is 6 The address can be changed manually in the SETUP REMOTE V IEC625 IEEEAS88 menu refer to SETUP Menu on page 2 19 Addresses between 0 and 30 can be selected Manually 1 Select the SETUP REMOTE V IEC625 IEEE488 menu 2 Enter the desired address 3 Terminate the address entry with 1x ENTER key The remote control status is indicated by the REM and LLO LEDs on the STATE signal field In this status all readouts appear on the screen DDS200 Digital Demodulation System User Manual Remote Control Return to Manual Control Return to manual control can be made via the front panel or via the IEC IEEE bus Manually 1 Press any key on the front panel Then actuate the LOCAL softkey NOTE Prior to the switch over the commands must have been fully processed since remote control is immediately switched on again The return to LOCAL key can be locked by the universal command LLO see Appendix A in order to prevent inadvertent switch over It is then only possible to switch to manual control via the IEC IEEE bus Locking of the LOCAL key can be cancelled by deactivating the REN line of the IEC IEE
121. he numeric keypad The new time is set after confirmation with the ENT key To change the date press the DATE soft key and proceed in the same way Remote This menu enables the remote control interfaces of the unit to be configured see Figure 2 17 This menu is entered by pressing the REMOTE soft key in the main setup menu 2 20 DDS200 Digital Demodulation System User Manual Manual Operation E RENOTE RF LEVEL 363 250 md ee 3 o 25 IEEE488 RS232 Figure 2 17 SETUP REMOTE menu Table 2 1 lists the SETUP REMOTE menu choices Table 2 1 SETUP REMOTE menu selections Menu Function IEC 625 IEEE488 Setting the IEC IEEE bus address RS 232 Setting the RS232 interface parameters m JTEC625 IEEE488 Menu The address for the IEC IEEE bus interface is entered here This address must correspond to the address used for the IEC IEEE bus controller to enable the remote control of the unit via the bus refer to Remote Control The entry is performed using either the cursor keys or the numeric keypad Values must be in the range of 0 to 30 DDS200 Digital Demodulation System User Manual 2 21 Manual Operation 2 22 SETUP TEC625 TEEE488 RF RF LEVEL 363 250 MHz 220 4 dBu IEC BUS ADRESS Figure 2 18 SETUP REMOTE IEC625 IEEE488 menu m RS232 Menu The RS232 interface parameters are entered here see Figure 2 19 The interface parameters must correspond to the parameters used for the controll
122. he unit can be positioned upright To position the unit upright perform the following steps 1 Fold out the rear feet until they lock in position The feet prevent the panel mounted connectors from being damaged 2 Place the unit on its rear feet Ensure that any cables connected to the rear panel will not be damaged 3 Check that the air outlet openings at the rear of the unit are not blocked Mounting the unit in a 19 inch Rack CAUTION To prevent damage to the unit when rackmounting make sure that the inlet air can flow freely to the vents at the right hand side and that the outlet air is not blocked at the rear panel The unit can be mounted in a 19 inch rack by means of Rack Adapter ZZA93 The mounting instructions are enclosed with the adapter DDS200 Digital Demodulation System User Manual Preparation for Use Connecting the Unitto the Since the unit has a switching power supply it can be operated in the range of AC Supply 100 V to 120 V 41 1096 1596 or 220 V to 240 V 41096 1596 at 47 Hz to 63 Hz without switch over The power supply has two primary fuses which are accessible on the rear panel Depending on the configuration of the unit the current drain is rated at 2 5 A in the range 100 to 120 V and 1 3 A in the range 220 to 240 V approximately 100 W at the secondary 100 120V 2 5A 220 240V 1 3A AUTOMATIC VOLTAGE SELECTION F1 F2 IEC 127 T3 15 H 250 V 50 60 Hz
123. hin the valid range 2 6 DDS200 Digital Demodulation System User Manual Manual Operation VARATION DATA Prae AMS 0 Esc cur 0 Optionally the frequency can also be modified with the two cursor keypad keys and The RF frequency is also indicated on the status line above the menu box see Figure 2 6 d It is thus possible to see the current RF frequency setting after changing to another menu E RF SET RF eee LEVEL 330 000 eee T um Hz Figure 2 6 RF menu DDS200 Digital Demodulation System User Manual 2 7 Manual Operation Basic Operation Overview 2 8 The different functional groups of the front panel and the basic operating steps are described in the following subsections Overview page 2 8 Display page 2 9 LEDs page 2 11 Soft Keys page 2 12 Cursor Keys page 2 13 Numeric Keypad page 2 14 Selecting Settings page 2 14 Editing Text and Numerals page 2 15 Presetting the Unit page 2 16 Hardcopy Key page 2 17 Storing Device Settings page 2 17 Hard Keys page 2 18 After power on measurement is performed with the settings that were active before the unit was powered off The MEASURE menu is always shown on the display This menu shows the results and the test parameters relevant to the current measurement function The hard keys are used to change to the setting menus
124. his the residual carrier power Prc is obtained Moreover the effective signal power Pgig can easily be determined from the constellation diagram It depends on the order of the QAM CS 10 log Pre Pe dB W S N Ratio and Interferer To determine the signal to noise ratio SNR and the suppression of a sinusoidal interferer only the four innermost decision fields of the constellation diagram are used From the two dimensional frequency distribution it is determined if it is a pure Gaussian distribution or if a sinusoidal interferer is present additionally or exclusively If the latter is the case the component is determined from the frequency distribution and from this the C I ratio is obtained C I 10 log Ps dB To determine the amplitude of the interferer the frequency of occurrence along a line running through the center point of a decision field is read out Sectional views of a signal free from noise and phase jitter are shown in Figure 2 54 DDS200 Digital Demodulation System User Manual 2 69 Manual Operation 2 70 Frequency of occurrence Calculated center point of decision Decision field Decision threshold threshold A Ideal QAM signal Frequency of occurrence n Calculated center point of decision Decision field Decision threshold threshold B QAM signal with interferer Figure 2 54 Sectional view for ideal signal a and signal with interfe
125. iagram a phase error shows up by the signal states being arranged in a rhombus rather than a square See Figure 2 49 Constellation diagram 64 QAM Cos 15 41 7MB s Options c X Quadraturphase Inphase Figure 2 49 Constellation diagram of 64QAM signal with 8 phase error DDS200 Digital Demodulation System User Manual Manual Operation Interferer Interferers are sinusoidal spurious signals occurring in the transmission frequency range and superimposed on the QAM signal at some point in the transmission path After demodulation the interferer is contained in the baseband in the form of low frequency sinusoidal spurious signals The frequency of these signals corresponds to the difference between the frequency of the original sinusoidal interference and the carrier frequency in the RF band In the constellation diagram an interferer shows up in the form of a rotating phasor superimposed on each constellation point Figure 2 50 is an example constellation when there is single interferer and other impair ments The constellation diagram shows the path of the phasor as a circle around each ideal constellation point Constellation diagram 64 QAM Cos 15 41 YMB s Options i Quadraturphase 9900 0000 Inphase Figure 2 50 Constellation dia
126. ically to given conditions m If the receiving conditions are known and a shorter equalizer should be simulated the central coefficient may be set to a position above 12 Generally the yellow LED next to the SPECIAL FUNCTION key comes on if a central coefficient outside the range 6 to 18 is selected The preset value is 12 ROLLOFF FACTOR The ROLLOFF FACTOR key is pressed to define the root cosine pulse shaping of the digital input filter For compliance with the first Nyquist condition pulse shaping in the whole transmission path must be symmetrical to the 6 dB point at the Nyquist frequencies According to DVB specifications the rolloff factor in the modulator is 0 15 The same rolloff factor must be set in the receiver Another factor may be chosen for laboratory tests MIN BER INTEGRATION With the MIN BER INTEGRATION key the BER measurement can be influenced For details on operation and usefulness of this setting refer to Selection of Integration Time for BER Measurement on page 2 79 For details on the BER EXTERN mode refer to BER Measurement with External Equipment on page 2 80 Note that in this case the serial and parallel MPEG outputs are disabled and only the female connectors X6 serial clock and X5 serial data are active Using the integrated PLL any jitter can be removed from the signals When the MIN BER INTEGRATION setting is changed the ALARM register is cleared The preset value is 10 samples LOOP BANDWI
127. ile the program is running 285 Program syntax error The remote loaded program contains a syntax error 286 Program runtime error Program runtime error DDS200 Digital Demodulation System User Manual C 7 Appendix C List of Error Messages Device Specific Error cause bit 3 in the ESR register to be set Table C 4 Device specific error Error number 300 Test displayed upon an error queue query Explanations Device specific error EFA specific error that cannot be defined more precisely 310 System error This error message signals a device specific error Please contact the R amp S service 311 350 Memory error Error in the device memory Queue overflow This error code is entered into the queue in lieu of the code that caused the error when the queue is full It indicates that an error occurred but was not recorded Five of these codes are accepted by the queue Query Errors cause bit 2 in the ESR register to be set Table 5 Query errors Error number 400 410 Test displayed upon an error queue query Explanations Query error Generic query error that cannot be defined more precisely Query INTERRUPTED The query was interrupted Example the device receives new data after a query before the response was completely sent 420 430 440 Query UNTERMINATED The query is incomplete Example the device is addressed as a talker and receives inco
128. iliarizes the user with the operation and basic functions of the DDS200 The device settings are described in detail in the subsections referenced in each step 1 Powering on the unit page 2 2 2 Selecting the mode page 2 3 3 Selecting the input page 2 4 4 Setting the RF Channel page 2 6 Prior to powering on check that the unit is connected to the AC supply If the power supply is correct the yellow standby LED lights above the power key on the lower right of the front panel refer to POWER in Table 1 1 on page 1 2 Power on the unit by pressing the power key The green LED lights After power on the DDS200 executes the following procedures 1 AnLED test is performed after power on to ensure that all the LEDs operate correctly 2 Astart up display appears on the LCD display showing the unit description the firmware version the IEC IEEE bus address and the parameters of the RS 232 interface 3 The status of the installed hardware modules is displayed next The display shows the firmware version the hardware version and the model 4 After the test of the hardware modules the unit is ready for operation and the QAM MEASURE Menu appears on the LCD display see Figure 2 2 DDS200 Digital Demodulation System User Manual Manual Operation QAH NEASURE SET RF RF LEVEL 330 000 HHz 66 7 dBuv C HSTELL DIAGRAM 66 7 dBuv 6 5E 6 rr 103 SPECTRUM ECHO PATTERN SYMBOL RATE 6 900 MSPs ORDER OF
129. information To write us For application oriented questions about a Tektronix measure ment product call toll free in North America 1 800 TEK WIDE 1 800 835 9433 ext 2400 6 00 a m 5 00 p m Pacific time Or contact us by e mail tm app supp tek com For product support outside of North America contact your local Tektronix distributor or sales office Contact your local Tektronix distributor or sales office Or visit our web site for a listing of worldwide service locations http www tek com In North America 1 800 TEK WIDE 1 800 835 9433 An operator will direct your call Tektronix Inc P O Box 1000 Wilsonville OR 97070 1000 Table of Contents General Safety Summary Preface e aie Sie Ur ERR nr mpeg vin ma e Rie t epa re Preparation for Use Legends for the Front and Rear View Front Panel ee RR RR RUE ae a ae DR taken ae UR ANUS Rear Panel quo E UI PRI Unpacking the Unit 7 oes oque Ute o e Pestis o pe e tiic TR EUR S INCCeSSOEIeS s nts RI ER Standard AcCCessories ose a Lue UR E RAE AR e Pete USATE ODpUODnS eu LAT RR E QUE QUERER RC AA S artt RR AER Optional AGCeSSOTIeS i3 ose oq S Pest C AES RR A TR RU S IristallatIOD DUCES Re ER Positioning the Unt ode aU te RU S Pest t C die AES RIA TR EUR S Conne
130. information on the current operating status of the instrument and on errors see Figure 3 4 on page 3 22 Such information is stored in the status registers and in the error queue The contents of the status registers and of the error queue can be queried via the IEC IEEE bus The information is hierarchically structured The topmost level is formed by the Status Byte Register STB defined by IEEE 488 2 and the associated mask register Service Request Enable SRE The STB receives its information from the Standard Event Status Register ESR also defined in IEEE 488 2 and the associated mask register Standard Event Status Enable ESE as well as from the SCPI defined STATus OPERation and STATus QUEStionable registers which contain detailed information on the instrument The status reporting system also includes the IST flag Individual STatus and the Parallel Poll Enable Register PPE assigned to it The IST flag just as SRQ combines the complete device status in a single bit The PPE for the IST flag has an analog function like the SRE has for the Service Request The output buffer contains the messages returned by the device to the controller It is not part of the status reporting system but since it determines the value of the MAV bit in the STB it is also shown in Figure 3 4 on page 3 22 Structure of a SCPI Status Each SCPI register consists of five registers of 16 bits each and with different Register functions see Figure 3
131. ing the instrument The covers are fastened in place The vents on the right at the side as viewed from the front and the blowers in the rear are not covered The AC supply voltage is within 100 V to 120 V or 220 V to 240 10 15 Voltages applied to the inputs do not exceed the permissible limits even the switched off state The outputs of the instrument are not overloaded or incorrectly connected EMC protective measures see page 1 11 are met Failure to observe the above Caution may cause damage or malfunction of the instrument The switching power supply automatically selects the correct voltage range 100 V to 120 V or 220 V to 240 V 41096 15 DDS200 Digital Demodulation System User Manual 1 9 Preparation for Use Positioning the Unit 1 10 The DDS200 is designed for use indoors The location must meet the following requirements m Ambient temperature must be between 0 and 50 W The vents on the right at the side as viewed from the front and the air outlet at the rear must not be covered The minimum distance to the nearest wall must be four inches ten centimeters m The unit must be placed on a flat surface Positioning the unit flat The bottom of the unit is fitted with feet To obtain an optimum viewing angle lift the unit at its front and fold the feet down until they lock in position Positioning the unit upright The unit also has four feet on the rear panel so that t
132. ion STATistics See page 2 38 HCOPy ALARm ddd Printing of last lines ddd of alarm LAST register See page 2 38 HCOPy ALARm ddd eee Printing of lines ddd to eee of alarm LINes register See page 2 38 HCOPy ALARm ON OFF bzw 1 0 Continuous output of current alarm ACTual 1 0 ings HCOPy ALARM ACTual DDS200 Digital Demodulation System User Manual D 19 Appendix D List of Commands D 20 DDS200 Digital Demodulation System User Manual Pp IKE rg Appendix E Programming Examples The following examples can be used as a basis for solving complex program ming tasks The programming language used is QuickBASIC It is also possible to translate the programs into other programming languages QuickBasic must be started from the directory in which it is installed using the following command QB L QBIB QLB Incorporating IEC IEEE Bus Library for QuickBASIC REM TEC Bus Bibliothek f r QuickBASIC einbinden INCLUDE c qbasic qbdecl bas Initialization and Initial Status When program is started both the IEC IEEE bus and the device settings are set to a defined status using the subroutines InitController and InitDevice Initialization of Controller REM Initializes controller eee REM InitController iecaddress 6 I EC IEEE bus address of device CALL IBFIND DEV1 efa Opens channel to device CALL IBPAD efa iecaddress Transfers device ad
133. ion System User Manual Manual Operation NOTE A disabled alarm is not stored in the alarm register Disabling the MPEG data alarm is only useful if you are not interested in the data errors DE If you disable the MPEG data alarm fewer errors are generated and you can keep longer logs of other errors Alarm Register The alarm register is an internal memory where alarm messages are stored together with their respective date and time The memory has a depth of 1000 lines and is in the form of a ring register Every second the DDS200 checks whether any of the following errors has occurred in the QAM signal m Input level LV level at the analog RF or IF inputs is below the threshold see page 2 41 m Synchronization SY frame synchronization of MPEG transport stream m Bit error rate BE is above the threshold see page 2 41 m Data error caused by uncorrectable events DE If one of the above mentioned errors is identified it is entered in the register with the abbreviation in brackets For disabling messages refer to page 2 38 Please note the following If several data errors occur within one second the error messages DE combined into one entry Alarm messages not registered every second in the alarm register An alarm is recorded once at the time when it first occurs and at the time when it disappears for the first time When alarm has been DISABLED in the ALA
134. ion System User Manual vii Table of Contents List of Tables viii Table 1 1 Legend for front view eee 1 2 Table 1 2 Legend for rear View 1 5 Table 2 1 SETUP REMOTE menu selections 2 21 Table 2 2 Messages displayed in the MEASURE menu 2 47 Table 2 3 Suitable limit values for QAM parameters 2 55 Table 2 4 DDS200 Preset Values 2 58 Table 2 5 Theoretical maximum and minimum values of calculated parameters for various orders of QAM 2 74 Table 2 6 Limit values for modulation error 2 75 Table 2 7 Limit values for modulation error 2 76 Table 2 8 Assignment of parallel MPEG data interface 2 86 Table 2 9 Cascading of two 0052005 2 88 Table 3 1 Synchronization with OPC OPC and WAI 3 18 Table 3 2 Definition of bits in the Status Byte Register 3 23 Table 3 3 Definition of bits used in the Event Status Register 3 24 Table 3 4 Definition of bits used in the STATus OPERation Register 3 25 Table 3 5 Definition of bits used in the STATus QUEStionable Register 3 26 Table 3 6 Resetting the device functions 3 28 Table 4 1 Assignment of error message numbers to binary error code
135. ion also contains detailed descriptions of the menus and submenus Section 3 explains the remote control of the digital demodulation system using the IEC 625 IEEE 488 bus and the RS232 interface Section 4 discusses maintenance and troubleshooting procedures that an operator can perform Section 5 has the following appendices W Appendix A provides the specifications certifications and compliances for the DDS200 W Appendix B contains information about the IEC IEEE bus interface m Appendix C lists the error messages that you may encounter while using the digital demodulation system Appendix D lists all the commands that can be used to remotely operate the digital demodulation system W Appendix E provides programming examples that you can use as an aid to solving complex programming tasks m Appendix F provides information about the RS 232 C interface Section 6 is the index DDS200 Digital Demodulation System User Manual xiii Preface xiv DDS200 Digital Demodulation System User Manual E Preparation for Use This section discusses general instructions on the preparation for use and the operation of the DDS200 Digital Demodulation System It contains brief explanations of the controls and connectors on the front and rear panels This section also provides instructions on operating the DDS200 for the first time Legends for the Front and Rear View The controls a
136. is disabled It serves for recording of incoming alarm messages Date and time are indicated in each printed line NOTE With no printer connected or if a connected printer has run out of paper an error message is displayed briefly and printing is interrupted This also happens when the actual line is printed PRINT ACTUAL After the error has been eliminated for example a printer is connected the setting must be selected again When the LAST LINES key is pressed any number of lines can be printed starting from the alarm message received last When the LAST LINES soft key is pressed the menu shown in Figure 2 36 is displayed QAH E PRINT LAST SET RF a mi LEVEL 330 000 l a dBu LAST LIHES Figure 2 36 ALARM PRINT LAST LINES menu The value can be varied by an entry on the numeric keypad terminate with ENT or by means of the cursor keys The entered numeral indicates the number of lines to be printed starting from the last line Once the correct number has been entered printing can be started by pressing PRINT DDS200 Digital Demodulation System User Manual Manual Operation Printing of alarm messages with LINE is performed in a similar way Contrary to the printout selected with LAST LINES any group of lines in the alarm register can be printed The DDS200 asks for the start and end line numbers which can be entered separately Entries are made in the same way as describe
137. is the C N ratio is obtained as follows C N dB Nus The noise level and thus the BER can be changed by modifying the attenuator The relationship between the BER and the signal to noise ratio C N will be examined in the next section BER as a Function of C N Calculation of Further Parameters If a QAM signal is disturbed by additive Gaussian noise error free demodulation is not possible The error frequency is indicated by the bit error rate Figure 2 61 shows the theoretical relationship between the C N ratio and the bit error rate Any additional errors that may occur cause a shifting of the displayed curves corresponding to the magnitude of the error and thus an increase of the bit error rate DDS200 Digital Demodulation System User Manual Manual Operation 1 e 100 le101 110 2 1e 10 3 le104 11077 110 6 110 7 110 8 1 10 110 10 1910 11 110 12 4 6 8 10 1 16 Figure 2 61 BER as a function of C N ratio 18 BER for 4 16 64 256 QAM Actual C N Noise margin 16 QAM 64 QAM 256 QAM 20 22 24 26 28 30 32 34 36 38 40 C N in dB DDS200 Digital Demodulation System User Manual 2 83 Manual Operation 2 84 It should be noted that the C N ratio shown in Figure 2 61 was measured after the receive filter 1st Nyquist condition fulfilled Therefore when comparing the curves with curves obtained for a channel a correction of the C N values has to be made The C N value
138. itude frequency response and group delay distortion resulting from the lowpass characteristics of cables and amplifiers and from amplitude and phase ripple from channel filters In contrast to the errors described previously the three types of errors listed here can be compensated well by the test receiver This is possible using a self adapting FIR filter equalizer integrated in the instrument For a compensation of errors by the equalizer the following main requirements must be fulfilled m The noise ripple must not exceed a certain frequency limit m The amplitude of the ripple must not be too high 2 78 DDS200 Digital Demodulation System User Manual Manual Operation W Echoes must not exceed 6 dB after 100 ns and 20 dB after 2 5 us Any echoes occurring after 2 5 us will not be compensated Selection of Integration Time for BER Measurement For BER measurements the measurement speed and stability of display can be modified To illustrate this the principle of BER measurement is briefly described below The DDS200 continuously evaluates the error correction events of the incoming DVB data stream This is accomplished using bit by bit comparison of the nominal and the actual data streams bits of a 204 byte 1632 bit frame are checked for coincidence Every deviation is counted The counter is read after 6127 frames and the count stored in a dynamic memory of 1000 locations Depending on the BER rate the test depth m
139. l In this mode no BER measurement via the IEC IEEE bus can be performed and all MPEG outputs are disabled Before the other keys for configuring the diagram will be described the basic diagrams are explained Figure 2 39 shows a constellation diagram with no input signal present only the noise is displayed Noticeable is the gradually decreasing density of measured values towards the outside Figure 2 40 shows a QAM signal with unsynchro nized symbol clock The characteristic here is the clear spatial limitation of measured values For a correct synchronization of this signal the order of QAM and or the symbol rate should be checked refer to SYMBOL RATE on page 2 30 Figure 2 39 Noise at input no QAM signal DDS200 Digital Demodulation System User Manual Manual Operation Figure 2 40 QAM signal with unsynchronized carrier and symbol rate Figure 2 41 shows a 64QAM signal with synchronized symbol clock rate However the constellation diagram rotates about its center because the carrier is not synchronized CARRIER RECOVERY This may happen for instance when the set frequency is not correct Figure 2 41 QAM signal with unsynchronized carrier DDS200 Digital Demodulation System User Manual 2 51 Manual Operation Figure 2 42 shows a constellation diagram with correct synchronization Figure 2 42 Correctly synchronized 64QAM signal Figure 2 43 shows the CONSTELLATION DIAGRAM menu
140. l function see SPECIAL FUNCTION Menu on page 2 34 Pre echoes are at the left of the central tap post echoes at the right Pre echoes may be caused by cross talk in filters post echoes are mainly due to reflections The diagram is divided into time intervals of one symbol each The symbol period Ts is set by means of the reciprocal symbol rate SR in the STATUS SYMBOL RATE menu refer to SYMBOL RATE on page 2 31 The following applies T 1 SR The symbol rate in samples per second should be used in this case With SR 6 900 MSPS the symbol period is 144 9 ns The unit of the level scale is dB Both scales of the echo diagram are fixed and cannot be varied NOTE The spectrum and echo displays are simply different ways of looking at the linear distortions in the transmission channel and are not completely independent of each other The only difference is that the equalizer coefficients are interpreted in different ways DDS200 Digital Demodulation System User Manual 2 57 Manual Operation Preset Values and Menu NOTE PRESET values are printed in bold Overview Table 2 4 DDS200 Preset Values INPUT RECEIVER page 2 27 ATTENUATION AUTO AUTO LOW NOISE AUTO LOW DIST AUTO LOWS DIST MANUAL 10dB PREAMPLIFIER RF RF numeric entry 330 MHz page 2 29 RCL RF STO RF RIGHT LEFT GET CHAR DEL CHAR ENTER STATUS SAW FILTER BW OFF page 2 30 page 2 31 8 MHz SYMBOL RATE UPPER SEARCH LIMIT
141. lt 1 5 dB Symbol rate typical 1 5 to 7 0 MBaud When setting the symbol rate value the accuracy should be to three decimal places p Symbolrate 6 9 MBaud Equalizer Self adapting selectable with freeze mode Reed Solomon decoder 204 188 byte t 8 selectable Bit error rate display range 103 to 10 10 Interleaving Forney L 12 Energy dispersal IESS 309 to DVB specification Internal Noise Generator Option B5 Signal Noise ratio typical 12 to 62 dB Resolution 0 1 dB Filter selection Automatic conversion and correct setting of S N ratio based on selected filter Outputs Parallel MPEG2 transport Connector rear panel 25 pin stream Standard LVDS 188 or 204 bytes DVB A010 Source impedance typical 100 Q DC component typical 1 25V Signal amplitude typical 247 mV to 454 mV Transmission link length Approximately 5 meters Max Serial MPEG2 transport stream Connector rear panel female type BNC Standard ASI Source impedance typical 75 Q DC component typical 0v Signal amplitude typical 0 9 Vp p Transmission rate typical 270 Mbit s Fixed QAM serial data Connector rear panel female type BNC before Reed Solomon Source impedance typical 75 Q QAM serial clock output Connector rear panel female type BNC Source impedance 750 typical A 2 DDS200 Digital Demodulation System User Manual Appendix A Specifications Table A 1 Electrical Specifications cont Cha
142. measured value M 12th measured value oo 1th measured value LLL th measured value LLL 15th measured value OF 46th measured value Figure 2 38 Recording the BER running BER calculation over 10 samples The BER measurement is restarted each time the alarm register is initialized automatically refer to Clearing the Register on page 2 45 Moreover a new BER measurement is triggered whenever the attenuator of the DDS200 is manually or automatically set For further information on BER measurements refer to Selection of Integration Time for BER Measurement on page 2 79 and BER Measurement with External Equipment on page 2 80 NOTE If FRAME UNSYNC is displayed in the MEASURE menu the DDS200 has found no MPEG sync word in the transmitted data This happens when the modulator is operated with PRBS data In this case the BER measurement is not useful If MIN BER integration has been has bee set to BER EXT in the SPECIAL FUNCTION menu EXTERNAL is displayed instead of the measured BER In this case frame synchronization can no longer be identified Refer to MIN BER INTEGRATION on page 2 35 DDS200 Digital Demodulation System User Manual 2 49 Manual Operation 2 50 Constellation Diagram Using the CONSTELL DIAGRAM key the DDS200 is switched to the constellation analyzer mode The constellation diagram is an extremely useful tool for assessing the quality of the transmitted signa
143. menu selected RF SET RF asm LEVEL 730 000 ml 0 asm T um Hz 2 9 The type of representation and selection for a soft key can vary depending on the unit setting soft key text highlighted Function active Soft key text not highlighted Function inactive but can be activated soft key text in italics and not highlighted Function inactive and cannot be activated When you press an available soft key unavailable keys are italicized the associated function is selected and another submenu if any is pulled down To quit a submenu press the ESC key in the cursor keypad see page 2 13 The previous menu is displayed The width and type of representation of the soft key bar vary depending on the parameters to be selected and displayed NOTE If a parameter can also be varied in the setting selected the parameter is displayed next to it on the screen DDS200 Digital Demodulation System User Manual Manual Operation Cursor Keys The numeric keypad and the cursor keypad can be used to vary parameters The two keys 4 and are for increasing or decreasing the value The two keys 4 and are for shifting the cursor below the parameter to the left or right The cursor is placed under the figure which is to be modified with the other two keys The overflow of a digit is automatically taken into account In contrast to a direct entry the value is modified stepwise via the n
144. modulation System User Manual Manual Operation INPUT Menu Input In the INPUT menu see Figure 2 23 the input selection attenuator and Selection preamplifier settings can be made INPUT SET RF RF LEVEL 330 000 HHz 66 7 dBu IHPUT 75 OHM REAR Figure 2 23 INPUT menu When the DDS200 used as a selective test receiver the RF input is reported in the INPUT menu using the RECEIVER soft key After pressing this key the input impedance and the active RF input are indicated in the display The message INPUT 75 OHM REAR indicates the X9 rear BNC connector is being used as the input connector With the message INPUT 75 OHM FRONT displayed the BNC connector on the front panel is used The IF input of the test receiver demodulator is activated with the IF key The input impedance is 50 Q The input is located at the rear of the instrument and marked X10 The INPUT ATTENUATION menu is displayed with the ATTEN key In the INPUT ATTENUATION menu see Figure 2 24 the input attenuation the tuner and mixer leveling as well as the preamplifier can be selected and set DDS200 Digital Demodulation System User Manual 2 27 Manual Operation 2 28 IHPUT RECEIVER ATTENUATION SET RF RF LEVEL 330 000 HHz 66 7 dBu AUTO AUTO LOW HOISE AUTO ATTENUATION O dB LOW DIST AUTO LOWEST DIST MAHUAL 1 dE PREAMP Figure 2 24 INPUT ATTENUATION menu When the AUTO AUTO LOW NOISE AUTO LOW DIST or AUTO LO
145. mplete data Query DEADLOCKED The query cannot be processed Example both input and output buffer are full and the device cannot continue Query UNTERMINATED after indefinite response A query is received in the same command line after a query requesting an indefinite response C 8 DDS200 Digital Demodulation System User Manual ey AR G Appendix D List of Commands Common Commands The DDS200 Digital Demodulation System supports SCPI version 1995 0 The instrument is remote controlled using mostly commands defined or recognized in this SCPI version Command systems not included in the SCPI standard are indicated Table D 1 Common Commands Command Data Meaning CLS Clear Status Data Structures ESE 0 to 255 Set Event Status Reg ESE Event Status Enable Query ESR Standard Event Status Query X DN Identification Query ST Individual Status Query OPC Operation Complete Command OPC Operation Complete Query PRE 0 to 65535 Set Parallel Poll Enable Register PRE Parallel Poll Enable Query PSC 32161 to 32767 Set Power On Status Clear 00 lt gt 0 0N PSC Power On Status Clear Query RCL 0to9 Recall Store 0 to 9 RST Reset Instrument 5 AV 0 to 9 Save Current State To Store 0 to 9 SRE 0 to 255 Set Read Service Request SRE m Enable Register STB A Status Byte Query TST Self Test Query WAI Wait For End Of
146. mum value of these results the peak MER modulation error ratio is calculated using the following formula error vector MER 100 68 where VM is the RMS value of the amplitudes of all ideal signal states To obtain the RMS modulation error the squares of the magnitudes of all differential vectors formed by the ideal and actual status vectors are added up and the number of symbols is counted Then the RMS modulation error is calculated as follows MERpys 100 i error vector E VM m 2 74 DDS200 Digital Demodulation System User Manual Manual Operation Figure 2 57 shows the vectors used for calculating the modulation error Actual status Q Error vector Ideal center point dise aet Figure 2 57 Positions of vectors used for determining the modulation error 64QAM first quadrant only The peak and RMS modulation error can also be specified on a logarithmic scale Conversion is done using the following formula MER jp 20 log dB For quantized I Q values the peak value is output in discrete form only since no averaging is performed in the calculation The RMS modulation error can be calculated within the limit values specified in Table 2 6 which lists the limit values obtained for quantized I Q values Table 2 6 Limit values for modulation error 16 1 39896 43 32 46dB 32 1 976 29 33 43dB 128 1 95296 13 6
147. n path See page 2 46 READ ALARm 1 0 Indication if failure threshold for QAM RF level alarm is present QAM RF LEVel VU See page 2 38 READ ALARm 1 0 Indication If eror threshold for QAM BERate BER QAM is presently overranged See page 2 38 READ ALARm 110 Indication if QAM synchronization h tly fail QAM SYNChron as presenty aigi See section 2 5 7 READ ALARm 1 0 Indication if a QAM data error has QAM DERRor presently occurred See page 2 38 READ ALARm 110 Response whether RF level is threshold QAM RF LEVel below error threshold See page 2 38 READ ALARm ddd 40 ASCII characters Output of line ddd of alarm register to IEC IEEE bus controller LINE See page 2 38 Dataare sent without unit D 14 DDS200 Digital Demodulation System User Manual Appendix D List of Commands Table D 9 READ Commands Cont Command Data Reply data READ ALARm ddd LINE ACTual READ ALARm S TATistics 8 lines with 40 ASCII char acters each Meaning Output of number of line last entered in alarm register See page 2 38 Output of statistical information See page 2 38 Dataare sent without unit CONFigure Subsystem Table D 10 CONFigure Commands Command Data Reply data CONFigure ALARm ON OFF QAM RF LEVel 1 0 STATe CONFigure ALARm QAM RF LEVel STATe CONFigure ALAR m ON OFF QAM BERate 1 0 STATe CONFigure ALARm QAM BERate STATe CONFigure
148. nd are available in their original form The external BER measurement unit recognizes the data sequence and synchronizes to it The BER is determined by bit by bit nominal actual value comparison NOTE In normal DVB operation the DDS200 Digital Demodulation System automatically detects inversion of the received signal from the incorrect frame sync word and compensates the error by interchanging the I and Q data This condition is indicated by a warning on the display 1 INTERCHANGED In the above example there are no sync words and the unit cannot detect an inverted spectrum It must therefore be ensured that the transmitting spectrum is set correctly in the DDS200 otherwise the BER measurement unit cannot synchronize to the data sequence This setting is made in the menu SPECIAL FUNCTION MPEG DATA OUTPUT I Q INVERSION An inverted spectrum is always obtained with an odd number of down conversions with the frequency of the oscillator being higher than that of the carrier Instead of the noise generator and attenuator shown in the above diagram any DVB transmission line can be connected The effect of very long lines attenua tion or reflections for example can be examined in this way The DVB signal can be deteriorated by adding noise thus increasing the BER The increased BER can well be discerned from the constellation diagram The decisive criterion for the BER is the C N ratio of a signal If the internal noise generator i
149. nd indicators of the DDS200 are combined into color coded functional groups The individual groups of control elements are described in Table 1 1 front panel on page 1 2 and Table 1 2 rear panel on page 1 5 DDS200 Digital Demodulation System User Manual 1 1 Preparation for Use Front Panel Front view of DDS200 9 Tektronix DDS200 Digital Demodulation System STATE MAIN FUNCTION VARATION DATA K T CA gga sync INPUT SETUP wo COLO SLs LILI CE BBE CARES Esc een fewr Le J JL DISPLAY RF VIDEO AUDIO 9 yL 28 0 AUDIO OO 99 CJ 750 Q Zo 250 Table 1 1 Legend for front view Controls Connectors DISPLAY Description POWER LCD DISPLAY SOFTKEYS DISPLAY When the DDS200 is connected to an AC supply and the power key on the rear panel is pressed the yellow standby LED lights On pressing the standby key the standby LED turns off and the green LED lights indicating that the unit is now ready for operation Black and white LCD display 320 x 240 pixels with back lighting The displayed softkey labeling depends on the key pressed in the MAIN FUNCTION control section or on the submenu selected The softkeys are used to activate menu dependent functions With the rotary control it is possible to set the optimum contrast of the display to suit the
150. ndard Commands for Programmable Instruments SCPI describes a standardized command set for the programming of instruments regardless of the type of instrument or manufacturer The goal of the SCPI Consortium is to standardize device specific commands as much as possible For this purpose an instrument model has been developed which defines identical functions within an instrument or of different instruments Command systems have been generated and assigned to these functions so that it is possible to address identical functions by the same commands The command systems have a hierarchical structure Figure 3 1 shows this tree structure using a detail from the SOURce command system for controlling the signal sources of the instru ment The other examples of syntax and structure of the commands are mainly taken from this command system SCPI uses the same syntax elements as well as the common commands defined in the IEEE 488 2 standard The syntax of the responses is partly subjected to stricter rules than laid down in the IEEE 488 2 standard refer to Responses to Queries on page 3 9 The commands consist of a header and usually one or more parameters Header and parameters are separated by a white space ASCII code 0 to 9 11 to 32 decimal The headers may be composed of several keywords The query form is generated by appending a question mark directly to the header NOTE The commands used in the examples below are not necessarily impleme
151. ng 1 11 G General device settings 2 19 Index 1 Index H Handshake RS232 F 5 Hard keys 1 3 description 2 18 Hardcopy key 2 17 HCOPy commands D 19 I Q inversion 2 37 Initialization programming example E 1 INPut commands D 6 Input selecting 2 4 Input and output signals connecting 1 15 Installation 1 9 Installing firmware 1 13 options 1 16 Instrument settings description 2 19 Interface IEC IEEE bus connector 1 17 RS232 1 16 Interface characteristics B 1 Interface functions B 3 Interferer in phase jitter 2 72 sinusoidal 2 69 K Keyboard for digital data input 1 3 Keys cursor 2 13 hard 2 18 hardcopy 2 17 mode 2 25 numeric 2 14 soft 2 12 L LEDs description 2 11 Limits alarm 2 41 List management programming example E 2 LLO 1 3 Loop bandwidth 2 35 Index 2 Maintenance 4 1 battery 4 2 Manual operation 2 1 Measure menu 2 46 MEMory commands D 11 memory battery backed 1 15 Menu alarm 2 38 beeper 2 33 IEC625 IEEE488 2 21 input attenuation selection 2 27 input selection 2 27 measure 2 46 MPEG data outputs 2 36 printer selection 2 23 remote 2 20 RF 2 29 RS232 2 22 special function 2 34 status 2 30 symbol rate 2 31 Time Date 2 20 units 2 24 Menus setting 2 10 Messages error C 1 Mode selecting 2 3 Mode key 2 25 Modulation error 2 74 limit values 2 75 MPEG data frame size
152. nored If a bit is set in the SRE and the associated bit in the STB changes from 0 to 1 a Service Request SRQ will be generated on the IEC IEEE bus which triggers an interrupt in the controller configured for this purpose and can be further processed by the controller The SRE can be set by the command SRE and read out by the query SRE Table 3 2 Definition of bits in the Status Byte Register Bit No Definition 2 Error Queue not empty This bitis set when the Error Queue receives an entry If this bitis enabled by the SRE each entry of the Error Queue will generate a Service Request An error can thus be recognized and specified in detail by querying the Error Queue The query returns an informative error message This procedure is recommended since it considerably reduces the problems of IEC IEEE bus control 3 QUEStionable Status Summary Bit This bitis set if in QUEStionable Status Register an EVENtbitis set and the associated ENABle bit is set to 1 A set bit denotes a questionable device status which can be specified in greater detail by querying the QUEStionable Status Register 4 MAV Bit message available This bitis set ifa readable message is in the output buffer This bit may be used to automate reading of data from the device into the controller see Appendix D Programming Examples 5 ESB Bit Summary bit of the Event Status Register This bit is set if one of the bits in the Event Status Register is
153. nsible for paying all shipping charges duties taxes and any other charges for products returned to any other locations This warranty shall not apply to any defect failure or damage caused by improper use or improper or inadequate maintenance and care Tektronix shall not be obligated to furnish service under this warranty a to repair damage resulting from attempts by personnel other than Tektronix representatives to install repair or service the product b to repair damage resulting from improper use or connection to incompatible equipment c to repair any damage or malfunction caused by the use of non Tektronix supplies or d to service a product that has been modified or integrated with other products when the effect of such modification or integration increases the time or difficulty of servicing the product THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER WARRANTIES EXPRESS OR IMPLIED TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE TEKTRONIX RESPONSIBILITY TO REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES Contacting Tektronix Product Support Service Support For other
154. nt ed in the instrument DDS200 Digital Demodulation System User Manual 3 5 Remote Control Common commands Common commands consist of a header to which an asterisk is prefixed and one or more parameters Examples RST RESET resets the device ESE 253 EVENT STATUS ENABLE sets the bits of the Event Status Enable Register ESR EVENT STATUS QUERY queries the contents of the Event Status Register Device specific commands m Hierarchy Device specific commands have a hierarchical structure see Figure 3 1 The various levels are represented by compound headers Headers of the highest level root level have one keyword only This keyword stands for a whole command system Example SENSe This keyword denotes the command system SENSe For lower level commands the full path must be specified starting with the highest level in the left most position The individual keywords are separated by a colon Example SENSe FREQuency CENTer 100 0 MHz This command is at the third level of the SENSe system It sets the receive frequency to 100 0 MHz SENSe FREQuency SOUNd FILTer lee CENTer CHANnel SQUelch DEMPhasis Figure 3 1 Tree structure of SCPI command system using SENSe as an example 3 6 DDS200 Digital Demodulation System User Manual Remote Control m Optional keywords In some command systems it is possible to insert or to omit certain keywords These keywords
155. nt Status Register ESR and Event Status Enable Register ESE The ESR is already defined in the IEEE 488 2 standard It is comparable to the EVENt register of an SCPI register The Event Status Register can be read out by the query ESR The ESE forms the associated ENABle register It can be set by the command ESE and read out by the query ESE Table 3 3 Definition of bits used in the Event Status Register Bit No Definition 0 Operation Complete Upon reception ofthe OP C command this bit is set when all previous commands have been executed 2 Query Error This bitis set if the controller wants to read data from the instrument but has not senta data request command or if the controller does not fetch the requested data but sends instead a new command to the instrument A frequent cause is a faulty query which cannot be executed DDS200 Digital Demodulation System User Manual Remote Control Table 3 3 Definition of bits used in the Event Status Register Cont Bit No Definition 3 Device dependent Error This bitis set if a device dependent error occurs An error message with a number between 300 and 399 or a positive error number denoting the error in greater detail see Appendix B Error Messages will be entered into the Error Queue 4 Execution Error This bitis set if the syntax of the command received is correct but the command cannot be executed due to various marginal conditions An error mes
156. nt digits defining the length of the data block In the example above the four digits specify a length of 5168 bytes The data bytes follow next During the transmission of these data bytes all terminators and other control characters are ignored until all bytes have been transmitted In case of data elements comprising more than one byte the byte defined by the SCPI command FORMat BORDer will be transmitted first Overview of Syntax The following list provides an overview of the syntax elements Elements pe The colon separates the keywords of a command In a command line the colon following a semicolon identifies the highest command level The semicolon separates two commands in a command line It does not change the path The comma separates several parameters of a command The question mark forms a query asterisk identifies a common command 6999 Quotation marks denote the beginning of a character string and terminate it The double cross pound symbol denotes the beginning of block data s A white space ASCII code 0 to 9 11 to 32 decimal separates header and parameters An example of a white space is the space character Description of Commands Notation In Appendix D List of Commands all commands implemented in the DDS200 are tabulated according to the command system and described in detail The notation largely conforms to the SCPI standard Command table Command In the comm
157. ntains a syntax error Macro execution error The macro definition contains an error DDS200 Digital Demodulation System User Manual Appendix C List of Error Messages Table C 3 Execution errors Cont Error Test displayed upon an error queue query number Explanations 213 illegal macro label The macro label defined in the DMC command is not allowed Example the labelis too long The label is identical to the Common Command Header or contains an invalid header syntax 214 Macro parameter error The macro parameter wild card character is wrong Example 215 Macro definition too long The macro definition is too long 216 Macro recursion error The command sequence defined by the macro is trapped in a loop Example the event which would cause the macro to leave the loop does not occur 2711 Macro redefinition not allowed The macro label in the DMC command has already been defined elsewhere 218 Macro header not found The header of the macro label in the GMC Query has not already been defined 280 Program error Error in the execution of a remote loaded program 281 Cannot create program The attempt to create the program failed 282 illegal program name The program name is invalid Example the name refers to a program which is not available 283 illegal variable name The variable is not available in the program 284 Program currently running The desired operation is not possible wh
158. nu title appears in the top line m The status line is shown below the menu title Important parameters which help to interpret the test results are permanently displayed m The main part of the screen is used to display the test results Parameters related to each other are shown in a logical sequence Test results are cyclically refreshed they are always up to date and always show the current values In the QAM demodulator mode it is possible to display different measurement menus Selection is by means of soft keys displayed on the right of the screen refer to Soft Keys on page 2 12 DDS200 Digital Demodulation System User Manual 2 9 Manual Operation 2 10 GOAN NEASURE SET RF RF LEVEL 330 000 HHz 66 7 dBuv C HSTELL DIAGRAM 66 7 dBuv 5 6 ir du SPECTRUM ECHO PATTERN SYMBOL RATE 6 900 MSPS ORDER OF GAM 64 PARA METERS ADD HOISE DFF Figure 2 7 MEASURE menu Setting Menus The menu title is again displayed in the top line of these menus see Figure 2 8 As in the MEASURE menu a status line is displayed In this way important information and measured values can be read while setting parameters The allocation of soft keys is shown on the left in the current menu soft key bar If parameters can be varied by selecting soft keys these are inserted next to the soft keys on the screen Variable parameters are highlighted GOAN RF SET RF RF LEVEL 330
159. nual Manual Operation RF Menu Select the RF menu using the RF key in the MAIN FUNCTION block In this menu see Figure 2 25 the center frequency of the QAM signal carrier frequency can be set Ei RF SET RF Im LEVEL 330 000 Im T E Hz Figure 2 25 RF menu Pressing the RF key causes the currently set center frequency to be displayed This frequency can be changed with a 1 kHz resolution directly using either the numeric keypad or by using the cursor keys When the RCL RF key is pressed and the RF memory number entered a receive frequency previously stored with STO RF in the RF MEMORY can be recalled The RF memory number can be selected using the keypad or the cursor keys If the receive frequency is selected with the aid of the RCL RF function the RF memory number and the associated text are displayed in the header The currently set frequency can be stored in the RF memory with the aid of the STO RF key When the STO RF key is pressed the desired RF memory number can be entered on the keypad and confirmed with the ENT key After pressing the EDIT TEXT key the text assigned to the previously selected RF memory number can be edited see Figure 2 26 DDS200 Digital Demodulation System User Manual 2 29 Manual Operation 2 30 STATUS Menu Ban RE STO RE EDIT TEXT SET RF RF LEVEL 330 000 HHz 66 7 dBu MEMORY TERT CHARACTER USE CURS RKEYS TO SELECT D
160. o the device They control the device functions and request information The commands are differentiated according to two criteria 1 According to the effect they have on the device Setting commands trigger device settings for example resetting the instrument or setting the receive frequency Queries cause data to be provided for output via the IEC IEEE bus for example for device identification or query of the receive frequency 2 According to their definition in the IEEE 488 2 standard Common commands are precisely defined in their function and notation in the IEEE 488 2 standard They refer to functions such as the management of the standardized status registers resetting and selftest DDS200 Digital Demodulation System User Manual Remote Control Device specific refers to functions that depend on the device commands characteristics such as frequency setting large number of these com mands has also been standardized by the SCPI Consortium Responses Responses are messages sent by the device to the controller following a query They may contain results device settings or information about the device status refer to Responses to Queries on page 3 9 Structure and syntax of the device dependent messages are described on page 3 5 The commands are listed and explained in Description of Commands on page 3 11 Structure and Syntax of Device Dependent Messages SCPI Introduction Command Structure Sta
161. of error message numbers to binary error code Error number 23 22 21 20 19 18 17 16 EXEIE 13 mp 11 10 E Ds ERE Binaycode 0 JO 0 0 0 4 MSB AE 1 means that the test value is entered into the corresponding position 0 or 1 0 means that the associated bit is always set to 0 this error number is not used The resulting bit sequence is considered as a digital number and displayed in hexadecimal format on the screen as soon as it is not 0 This number can be reconverted by replacing each individual hexadecimal digit by the associated binary value according to the following table Table 4 2 Conversion of displayed hexadecimal code into binary code Hex f e d b a 9 8 7 6 3 4 3 2 1 0 1111 1110 1101 1100 1011 1010 1001 1000 0111 0110 0101 0100 0011 0010 0001 0000 Example message on display SELFTEST ERROR CODE 000300 Hex Binary 0000 0000 0000 0000 Error No 9 Error No 8 conversion of hexadecimal display acc to Table 2 Error No 8 power supply and No 9 oscillator level occurred in the QAM demodulator module because there is a 1 atthe relevant positions of the binary word Table 1 The error numbers are assigned to the errors occurring in the instrument as shown in the above list eg No 8 power supply 4 4 DDS200 Digital Demodulation System User Manual Pp K Appendix A Specific
162. on System User Manual Appendix F Remote Control via RS 232 C Interface Local Controller The DDS200 is connected to a controller using a zero modem cable The data Connection for Hardware control and signalling lines of this cable must be cross connected The following Handshake wiring diagram is applicable to controllers with 9 pin or 25 pin connectors DDS200 9 pins Controller 9 pins DDS200 9 pins Controller 25 pins 14 Figure F 3 Wiring for hardware handshake DDS200 Digital Demodulation System User Manual 13 C 25 DDS200 Controller decoder Signal pin 2 RxD TxD 3 3 TxD RxD 2 4 DTR DSR 6 5 GND GND 5 6 DSR DTR 4 7 RTS CTS 8 8 CTS RTS 7 DDS200 Controller decoder pin Signal pin 2 RxD TxD 2 3 TxD RxD 3 4 DTR DSR 6 5 GND GND 7 6 DSR DTR 20 7 RTS CTS 5 8 CTS RTS 4 F 7 Appendix F Remote Control via RS 232 C Interface F 8 DDS200 Digital Demodulation System User Manual Index A Alarm clearing register 2 45 configuring 2 38 printing register 2 43 register 2 39 setting limit values 2 41 statistics 2 41 Alarm messages order 2 40 Ambient temperature 1 2 Application examples manual operation 2 62 Bandwidth loop 2 35 Basic op
163. on System User Manual a fa E Appendix C List of Error Messages Table C 1 through Table C 5 contain all the error messages that may occur in the DDS200 Digital Demodulation System Negative error numbers are defined in the SCPI standard positive error numbers identify device specific errors The error code is queried by means of the SYSTem ERR command The left column of the tables gives the error code number In the right column the text of the error message that will be entered into the error event queue or shown on the display is written in bold with an explanation following the error message SCPI Specific Error Messages No error Table C 1 No error Error Test displayed upon an error queue query number Explanations 0 No error This message is displayed when there are no entries in the error queue Command Errors cause bit 5 in the ESR register to be set Table C22 Command errors Error Test displayed upon an error queue query number Explanations 100 Command Error Command faulty or invalid 101 Invalid Character The command contains a character which is invalid for that type Example a header containing an ampersand SOURCES 102 Syntax error Command invalid Example the command contains block data which the device does not accept 103 Invalid separator Command contains an illegal character where a separator is expected Example the semicolon omitted after the command DDS200 Di
164. on page 3 7 For compatibility with the SCPI standard the instrument must be able to recognize the full length of the command Parameters in square brackets may also be optionally inserted into the command or omitted The common commands are based on the IEEE 488 2 IEC 625 2 standard A specific command has the same effect in different instruments The headers of these commands consist of an asterisk followed by three letters Many common commandis refer to the status reporting system described in detail on page 3 19 DDS200 Digital Demodulation System User Manual Remote Control Command Parameter Unit Notes CLS Clear Status Data Structures ESE 0 255 Set Event Status Reg ESE Event Status Enable Query ESR Standard Event Sta tus Query IDN Identification Query IST Individual Status Query OPC Operation Complete Command Operation Complete Query PRE 0 65535 Set Parallel Poll En able Register PRE Parallel Poll Enable Query PSC 32767 32167 Set Power On Status Clear zz00FF lt gt 00N Power On Status RCL Clear Query Recall Store 0 9 ARST Reset Instrument Save Current State To Store 0 9 Set Read Service Request Enable Register Status Byte Query Self Test Query Wait For End Of Ac tion DDS200 Digital Demodulation System User Manual 3 13 Remote Control CLS
165. onstellation diagram of ideal 64QAM signal 2 63 Figure 2 48 Constellation diagram of 64QAM signal with 20 amplitude imbalance 2 64 Figure 2 49 Constellation diagram of 64QAM signal with 85 phase error 2 64 Figure 2 50 Constellation diagram of 64QAM signal with interferer 25 0 4 2 65 Figure 2 51 Constellation diagram of 64QAM signal with residual carrier in I component CS 17 6 dB 2 66 Figure 2 52 Constellation diagram of 64QAM signal with additive noise SNR 230 0 dB 2 67 Figure 2 53 Constellation diagram of 64QAM signal with phase jitter PJRMS 21 735 2 68 Figure 2 54 Sectional view for ideal signal a and signal with interferer b 5 22 ee ko n Rer I ee Re eal ES 2 70 Figure 2 55 Frequencies of occurrence shown by sectional views superimposed Gaussian curves at various noise levels and with same interferer for 64QAM 2 71 Figure 2 56 Improvement of accuracy with superimposed noise SNR 245 dB e heb Ree erem eae rx epoca ess 2 73 Figure 2 57 Positions of vectors used for determining the modulation error 64QAM first quadrant only 2 75 Figure 2 58 Intermodulation due to 2nd order nonlinearities 2 77 Figure 2 59 Intermodula
166. or amplitude with QAM measured value available only with setting SENS QAM MEAS z IMP See page 2 46 READ QAM dd dd PCT Query ofthe Q imbalance with IQ IMBalance QAM measured value available only with setting SENS QAM MEAS z IMP See page 2 46 READ QAM dd dd grd Query of the Q Phase error with IQ P HError READ QAM dd d CARRier SUP P Ression READ QAM 5 dd d dB SIGNal INTerference Dataare sent without unit DDS200 Digital Demodulation System User Manual QAM measured value available only with setting SENS QAM MEAS IMP See page 2 46 Query of the carrier suppression with QAM measured value available only with setting SENS QAM MEAS z IMP See page 2 46 Query of the signal interference with QAM measured value available only with setting SENS QAM MEAS IMP See page 2 46 D 13 Appendix D List of Commands Table D 9 READ Commands Cont Command Reply data Meaning READ QAM dd d 4rd RMS Query ofthe average phase noise PNOise measured value available only with setting SENS QAM MEAS z IMP See page 2 46 READ QAM dd d dB Query ofthe QAM signal noise SIGNalNOISe x gi measured value available only with setting SENS QAM MEAS z IMP See page 2 46 READ QAM dd dd PCT Query of amplitude non linearity of COMPression the the total transmissio
167. pendix A Specifications Table A 3 Power Characteristics Characteristic Description Line Voltage 85 to 132 VAC automatic selection 187 to 264 VAC Line Frequency 50 to 60 Hz Power Consumption 100 VA Table A 4 Environmental Characteristics Description 0 C t0450 C 45 C to 45 C 40 C to 70 C Characteristic Operating temperature range Rated temperature range Storage temperature range Table A 5 Physical Characteristics Dimension mm in Height 147 5 8 Width 450 17 7 Depth 460 18 1 Weight kg Ib Net 12 26 5 A 5 DDS200 Digital Demodulation System User Manual Appendix A Specifications A 6 DDS200 Digital Demodulation System User Manual P D Ii Appendix B IEC IEEE Bus Interface The DDS200 Digital Demodulation Sysem is fitted with an IEC IEEE bus interface as standard The connector for the IEEE 488 bus is located on the rear panel controller can be connected for remote control using a shielded cable for the connection Interface Characteristics The EC IEEE bus interface has the following characteristics Bus Lines 8 bit parallel data transmission Bi directional data transmission Three wire handshake High data transmission rate max 350 Kbyte s Connection of up to 15 devices Maximum length of connecting cables 49 feet 15 m length of single cable 6 feet 2 m Wired OR links when several devices are connected in
168. pendix E Programming Examples REM kkkkkkkkkkkkkkkkkk Service Request Routine kkkkkkkkkkkkkkkkkkkk Srq CLS Clears controller screen DO SRQFOUND 0 FOR 1 EFA TO EFAN Queries all bus users ON ERROR GOTO noTeilnehmer No bus user available GOSUB Operationstatus CALL IBRSP 1 STB Reads Serial Poll Status Byte IF STB gt 0 THEN This device has bits set in STB SRQFOUND 1 IF STB AND 16 gt 0 THEN GOSUB Outputqueue IF STB AND 4 gt 0 THEN GOSUB Failure IF STB AND 8 0 THEN GOSUB Questionablestatus IF STB AND 128 gt 0 THEN GOSUB Operationstatus IF STB AND 32 gt 0 THEN GOSUB Esrread END IF noTeilnehmer NEXT 1 LOOP UNTIL SRQFOUND 0 ON ERROR GOTO Fehlerbehandlung ON PEN GOSUB Srq RETURN Reactivates SRQ Routine End of SRQ Routine Readout of Status Event Registers output buffer and error event queue is carried out in subroutines REM x Subroutines for single STB bits Outputqueue Reads output buffer Nachricht SPACE 100 Provides space for response CALL IBRD efa Nachricht PRINT Message in output buffer message RETURN Failure Reads error queue ERROR SPACE 100 Provides space for error variable CALL IBWRT efa SYST ERR CALL IBRD efa ERRORS PRINT Fehlertext ERROR RETURN Questionablestatus Reads Questionable Status Register Ques SPACE 20 Preallocates text variable using spaces CALL IBWRT efa STA
169. pped and the data received so far are processed Data transfer from the IEC IEEE bus is then continued If the buffer is not yet full when a terminator is received the input unit can receive the next command while the previous command is identified and executed Reception of a DCL command clears the input buffer and immediately causes a message to be sent to the command identification The command identification analyzes the data received from the input unit proceeding in the order in which the data are received Only a DCL command will be given priority whereas a GET Group Execute Trigger command will be processed when the previous commands have been executed Each identified command will immediately be transferred to the data set however without being immediately executed there DDS200 Digital Demodulation System User Manual Remote Control Syntax errors in the command are recognized and passed on to the status reporting system The remaining part of a command line after a syntax error will be further analyzed as far as possible and processed If a terminator or a DCL is identified the command identification requests the data set to execute the setting commands in the device hardware The command identification is then immediately ready to process a new command This means that addtional commands can be processed while settings are being made in the hardware overlapping execution Data Set and Device The term device hardware
170. racteristics Requirements Measurement Displays Graphic Constellation display Calculated Biterror rate BER Frequency offset Supplemental information Level 1 0 phase error In degrees 1 9 amplitude Asa percentage imbalance Carrier suppression Residual carrier In dB Sinusoidal interference In dB Signal noise ratio S NR In dB Phase jitter In degrees Modulation error ratio MER Synchronization Information Symbol rate Carrier recovery Equalizer MPEG2 frame DDS200 Digital Demodulation System User Manual As RMS or peak value A 3 Appendix A Specifications Table 2 Certifications and compliances EC Declaration of Conformity EMC Meets intent of Directive 89 336 E EC for Electromagnetic Compatibility Compliance was demonstrated to the following specifications as listed in the Official oumal of the European Communities EN 55011 Class A Radiated and Conducted Emissions EN 55011 Class B Radiated and Conducted Emissions EN 50081 1 Emissions EN 55022 Class B Radiated and Conducted Emissions EN 60555 2 AC Power Line Harmonic Emissions EN 50082 1 Immunity IEC 801 2 Electrostatic Discharge Immunity IEC 801 3 RF Electromagnetic Field Immunity IEC 801 4 Electrical Fast Transient Burst Immunity IEC 801 5 Power Line Surge Immunity EMC Compliance Meets the intent of Directive 89 336 EE C Amended by 91 263 EEC 92 31 EEC 93 68 EE C for Electromagne
171. rd order A third order nonlinearity is caused by the cubic nonlinearity component of the amplifier characteristic For example intermodulation on a DVB channel Cy with a carrier frequency wy is obtained for the channel configuration Wy 2004 03 shown in Figure 2 59 DDS200 Digital Demodulation System User Manual 2 77 Manual Operation Amplitude A y 0 ON Q4 W3 204 W3 Intermodulation of C Further intermodulation and C in channel Cy of C3 and Figure 2 59 Intermodulation due to 3rd order nonlinearity Intermodulation between digital channels can be regarded as additive random noise since it has the effect of additive noise Therefore special requirements must be fulfilled with higher order QAM modulation Intermodulation between analog channels tends to be more like an interferor with some additional noise Intermodulation cannot be analyzed by means of the constellation diagram For the analysis methods described so far intermodulation is interpreted as noise possibly with some interference and covered by the S N and ratio information Frequency and phase errors echoes Possible causes m Reflections in cables echoes caused by mismatched cable terminations and return loss from the equipment connected m Tolerances of the pulse shaping filters resulting in inter symbol interference ISI because the first Nyquist criterion is not fulfilled m Ampl
172. re displayed in italics and cannot be selected HODE RF RF LEVEL 48 220 MHz 67 4 dBu ARRAS A Ae QAM DEMODULATOR LOE AL EE ag em sU AEE gx Figure 2 22 Mode menu NOTE The default setting selected in the MODE menu determines the overall operation of the unit and largely defines the presentation and the function of many menus DDS200 Digital Demodulation System User Manual 2 25 Manual Operation Operation as Demodulator for Quadrature Amplitude Modulated QAM Signals The DDS200 Digital Demodulation System measures QAM signals used in digital video broadcasting DVB A number of special characteristics for measuring DVB signals make this instrument especially suitable for accurate analysis and measurements of all main parameters refer to MEASURE Menu on page 2 46 Such characteristics the newly developed steep edge channel filters which were especially developed for use in cable channels the powerful equalizer and the DVB specific Nyquist filters The input signal is processed in compliance with DVB specifications This includes demapping the Reed Solomon decoder deinterleaving and energy dispersal Decoded MPEG data is available in serial or parallel form Extremely powerful digital signal processing provides accurate analysis of the applied QAM signal A newly developed data storage technique allows a very flexible and efficient collection of measurement results for all relevant signal paramet
173. red last even if there are more than 1000 entries in the alarm register With the aid of the statistics the user is able to assess the QAM signal over an extended period of time The error indication in is important as a proof for the correct functioning of a transmission link Printing the Register The currently displayed screen content can be printed any time by pressing the HARDCOPY key A precondition is that the printer driver in the SETUP PRINTER menu has been set correctly Since the alarm register or parts thereof can be printed in so many ways the selectable modes are offered in a separate menu This menu can be displayed by pressing the ALARM key in the MAIN FUNCTION block and then the PRINT soft key The menu shown in Figure 2 35 is displayed QAH ALARH PRINT SET RF RF LEVEL 330 000 HHz 66 7 dBu LAST LINES LIHE ACTUAL Figure 2 35 ALARM PRINT menu in the QAM demodulator mode DDS200 Digital Demodulation System User Manual 2 43 Manual Operation 2 44 The alarm register continues to be displayed only the soft keys have changed Now the desired printout can be selected Pressing the ACTUAL key once switches the DDS200 to a status where the head of the hardcopy with the most important settings is printed first Each subsequently arriving alarm message is then output separately to the printer In this case the ACTUAL field is in inverse video When the ACTUAL key is pressed again this function
174. rer b Along this section the local maxima of the frequency of occurrence characteristic are determined on both sides of the calculated center point To reliably identify an interferer the frequency of occurrence at the center point must be clearly smaller than at the local maxima The distance between the local maxima and the center point obtained for the four decision fields and then averaged corresponds to amplitude a of the interferer If noise SNR 38 dB is present in the signal a number of additional considerations apply For these additive noise with a Gaussian distribution is assumed The sectional view in this case shows two Gaussian curves more or less superimposed on each other This is demonstrated in Figure 2 55 by a few examples showing the single curves as well as the overall curve continuous line which can be determined by means of the sectional view DDS200 Digital Demodulation System User Manual Manual Operation gt gt 0 8 0 6 0 4 0 2 0 02 04 06 08 E 0 8 0 6 0 4 02 0 02 04 06 08 xd a C I 26 dB SNR b C I 226 dB SNR 36 dB n x EE 8 n x PENNE A 0 8 0 6 0 4 0 2 0 02 04 06 08 xid 0 8 0 6 0 4 02 0 02 04 06 08 xd c C I 226 dB SNR 32 dB d C I 226 dB SNR 29 dB Figure 2 55 Frequencies of occurrence shown by sectional views superimposed Gaussian curves at various noise levels and with same interferer for G4QAM If
175. rface Function x eost vec eet nee eer es tp me RR B 3 Interface Messages RI eR CERE TEE be B 3 Common Commands sees hne B 3 Addressed Commands B 4 Appendix C List of Error Messages C 1 SCPI Specific Error Messages C 1 Appendix D List of Commands eene D 1 Common Commands 0 cece cee eere D 1 STATus Subsystem ose e eee EE eee E E Re AER D 2 SYSTem Subsystet s mosce rhe RE e eee p ERE A ex D 4 ROUTe Subsystem vere er te RR ep tes D 5 INPut Subsystem leer eR Et ey Rr E A red D 6 SENSe Subsystem cibus e rer Rr t Ee EE e eR D 7 MEMory Subsystem llle D 11 UNIT Subsystem eet eR TOV E tes D 11 READ Subsystem osse rar eR E eR AE HERE ed D 12 CONFigure Subsystem lle D 15 Hcopy Subsystem s ies de em te RE EE EY Red D 19 Appendix E Programming Examples E 1 Incorporating IEC IEEE Bus Library for QuickBASIC E 1 Initialization and Initial Status E 1 Sending Device Setting E 2 Switchover to Manual E 2 Readout of Device Settings sosi essa ERR Ee E 2 Vist Management RR P EUR CLA Rc OR RR LA E RR E 2 Command Synchronization
176. rl C 03 hex Ctrl Q 11 hex Ctrl 5 gt 13 hex ODhex 0 Device Clear DCL Upon reception of this character processing of the commands just received is stopped and the command processing software is setto a defined status This character does not change the device setup Enables character output This character enables data transmission from the DDS200 Disables character output This character disables data transmission from the DDS200 Terminator CR gt lt LF gt DDS200 Digital Demodulation System User Manual Appendix F Remote Control via RS 232 C Interface NOTE When block data are transmitted via the serial interface control characters are not recognized as it is not possible to distinguish between block data and control characters in the data stream for block data see section 3 5 5 This means that control characters are interpreted as data bytes of the block data Handshake Software Handshake With software handshake data transmission is controlled by the two control characters XON char XOFF char The DDS200 signals via the control character XON char that it is ready to receive data If the receive buffer is filled to capacity the DDS200 prevents the controller from further data transmission by sending the control character XOFF char The controller interrupts data transmission until it receives again XON char from the DDS200 and signals to the DDS200 that it is ready to recei
177. rmed with the control on the right below the LCD display The contrast depends on the temperature and the viewing angle DISPLAY Installing Firmware Virtually all the firmware and software for the unit are stored in a flash EPROM which can be erased and rewritten without opening the unit and replacing components In case of a firmware update the new firmware version can be loaded via the series interface RS 232 connector on the rear panel from a PC Proceed as follows for a firmware update 1 Connect the unit to the PC COMI or COM2 using a null modem cable Power on the unit and the PC Press the PRESET key Select the submenu SERVICE FIRMWARE UPDATE EE Confirm the firmware update with YES The update is started as soon as the connection to the PC has been established At this stage the procedure can be aborted without loosing data by powering the unit off and on 6 Start the flashup software on the PC with flashup lt ENT gt The firmware update is running and must not be interrupted DDS200 Digital Demodulation System User Manual 1 13 Preparation for Use 1 14 Initial update No executable firmware in the unit If the unit does not have firmware remove the rear panel as described in Installing Options on page 1 16 The Main Processor board is located on the right at the bottom side as viewed from the rear panel The board can be recognized by the flat cable connected between it and the r
178. ror is returned by the instrument The error queue should be queried in the controller program after each SRQ since the queue entries provide a more precise description of the error cause than the status registers In particular in the test phase of a controller program the error queue should be queried at regular intervals since it also registers faulty commands from the controller to the instrument DDS200 Digital Demodulation System User Manual 3 27 Remote Control Resetting the Status Table 3 6 contains the various commands and events causing a reset of the status Reporting System reporting system None of the commands with the exception of RST and SYSTem PRESet affects the functional device settings In particular DCL does not clear the device settings Table 3 6 Resetting the device functions Event Switching on AC supply voltages DCL SDC Power On Status Clear gyetem STATus Effect 0 1 Device Clear PRESet PRESet CLS Clears STB ESR yes Clears SRE ESE Clears PPE Clears EVENt registers yes EE yes Clears ENABle registers of all yes yes OPERation and QUESTionable Registers fills the ENABle registers of all other registers with 1 Fills PTRansition registers with 1 yes yes clears NTRansition registers Clears error queue yes yes PF yes Clears output buffer yes yes yes i i Clears command processing and yes yes yes yes input buffer Any command that is the
179. rting System Table 3 5 Definition of bits used in the STATus QUEStionable Register Bit No Definition This register is not used For an efficient use of the status reporting system the information contained therein has to be transferred to the controller and further processed There are various methods which are described in the following Detailed program examples are given in Appendix D Program Examples Service Request Use of Hierarchical Structure Under certain conditions the instrument may send a service request SRQ to the controller This service request usually causes an interrupt at the controller to which the controller program can respond by suitable actions As shown in Figure 3 4 on page 3 22 a SRQ will always be triggered if one or several of the bits 2 3 4 5 or 7 have been set in the Status Byte Register and enabled in the SRE Each of these bits combines the information from a further status register from the error queue or the output buffer By setting the ENABle registers of the status registers accordingly any bit in any status register will be able to trigger a SRQ To utilize the possibilities of the service request all bits in the enable registers SRE and ESE should be set to 1 Example see also Figure 3 4 on page 3 22 and Appendix D Program Exam ples Use the OPC command to generate a SRQ 1 Setbit 0 Operation Complete in the ESE 2 Setbit 5 ESB in the SRE 3 The instrument gen
180. ry clean 64QAM signal see Figure 2 47 Constellation diagram 64 QAM Cos 15 41 7MB s Quadraturphase Inphase Figure 2 47 Constellation diagram of ideal 64QAM signal The following are examples of modulation errors and the resulting constellation diagrams m Amplitude Imbalance Amplitude imbalance describes the different gains of the I and Q compo nents of a signal Such a difference in amplitude is caused by different gain in the two signal paths I and Q of the transmitter In a constellation diagram amplitude imbalance shows by one signal component being expanded and the other one being compressed This is due to the fact that the receiver AGC makes for a constant average signal level See Figure 2 48 DDS200 Digital Demodulation System User Manual 2 63 Manual Operation 2 64 Constellation diagram 64 QAM Cos 15 41 7MB s Options Quadraturphase Inphase Figure 2 48 Constellation diagram of 64QAM signal with 20 amplitude imbalance Phase Error The phase error frequently also referred to as quadrature offset or quadrature error is the difference between the phase angles of the I and Q components referenced to 90 A phase error is caused by an error of the phase shifter of the I Q modulator The I and Q components are in this case not orthogonal to each other after demodulation In the constellation d
181. s D 7 Table D 7 MEMory Commands D 11 Table D 8 UNIT Commands D 11 Table D 9 READ Commands D 12 Table D 10 CONFigure Commands e D 15 Table D 11 HCOPy Commands D 19 Table F 1 Pin assignment of RS 232 C interface F 2 Table F 2 Control characters of RS 232 Interface F 4 DDS200 Digital Demodulation System User Manual ix Table of Contents X DDS200 Digital Demodulation System User Manual fcc if General Safety Summary Review the following safety precautions to avoid injury and prevent damage to this product or any products connected to it To avoid potential hazards use this product only as specified Only qualified personnel should perform service procedures To Avoid Fire or Use Proper Power Cord Use only the power cord specified for this product and Personal Injury certified for the country of use Use Proper Voltage Setting Before applying power ensure that the line selector is in the proper position for the power source being used Connect and Disconnect Properly Do not connect or disconnect probes or test leads while they are connected to a voltage source Ground the Product This product is grounded through the grounding conductor of the power cord To avoid electric
182. s case the entry in line 0 is no longer the oldest but the latest entry Three entries in the alarm register are made automatically by the DDS200 without an alarm message being received m Date and time when the register was cleared REG CLEARED m Date and time to which the internal system clock was changed last TIME CHANGED m Date and time at which the user disabled or enabled an alarm DDS200 Digital Demodulation System User Manual Manual Operation Setting Limit Values The DDS200 continuously monitors the applied QAM signal for compliance with set thresholds These limit values are error thresholds If one of these limits is exceeded the ALARM LED on the front panel lights and a message with data and time is entered in the alarm register provided this type of alarm is not disabled see page 2 38 and 2 39 This applies to the following parameters m LEVEL Monitoring of input level m BER Monitoring of bit error rate preset value is 1 0 E 4 For changing thresholds press the ALARM THRESH key in the ALARM menu The following menu shown in Figure 2 33 is displayed QAH ALARM THRESHOLD SET RF RF LEVEL 330 000 HHz Buy LEVEL lt 40 0 dBuv Figure 2 33 ALARM TRESH menu For setting the BER limit value the BER key has to be pressed A numeric value can now be directly entered The lowest useful threshold that can be entered is 0 1 E 09 In this case an alarm is triggered whenever the BER i
183. s not 0 0 E 09 If 0 0 E 09 is entered that is the alarm is continuously triggered 0 0 E 00 is displayed after confirmation with ENTER which is mathematically the same Statistics Messages in the alarm register of the DDS200 can be statistically evaluated The whole monitoring period is considered in the evaluation this includes all alarm messages that occurred between the last entry of REG WAS CLEARED or TIME WAS CHANGED and the calling up of the statistics function The evaluated period is indicated MONITORING TIME The statistics function is called up by first pressing the ALARM function key and then the STATISTICS soft key In this case the menu shown in Figure 2 34 is displayed DDS200 Digital Demodulation System User Manual 2 41 Manual Operation 2 42 DAH ALARM STATISTICS SET RF RF LEVEL 330 000 HHz 66 7 dBuv MOMITORING TIME 00 00 10 00 00 02 SYHCHRONISATIOW 00 00 04 BIT ERROR RATE 00 00 05 MPEG DATA ERROR TIME 45 MPEG DATA ERROR CHT 99 MPEG DATA CORR CHT Figure 2 34 ALARM STATISTICS menu The displayed times are the sums of times during which an alarm was active over the monitoring time In the case of a data error DE the number of events to be more exact the duration of the error in seconds is summed up Statistical values are calculated in addition and indicated as an error in The percentage values are always referenced to the elapsed monitoring time A 0 1396 for MPEG DATA ER
184. s not used the C N ratio can be measured with a spectrum analyzer For this the following steps are to be carried out m Select a high resolution bandwidth for example 300 kHz and a low video bandwidth on the spectrum analyzer so that signals are represented as lines and not as noise bars m Switch the noise generator off and measure the signal of the DVT 200 Digital Video transmitter on the spectrum analyzer For this set marker to the same frequency as the QAM carrier and select the NOISE marker mode The signal power density C is given in dBm Hz by the analyzer the filter bandwidth and the characteristics of the logarithmic amplifier of the analyzer DDS200 Digital Demodulation System User Manual 2 81 Manual Operation 2 82 are taken into account automatically To refer C to the Nyquist bandwidth Bw of the DVB signal the signal power C is to be calculated as follows C C 10lg By C 10lg symbol rate Hz dB dBm m Switch the signal of the DVT 200 Digital Video Transmitter off switch the noise generator on and measure the noise power density on the spectrum analyzer For this set a marker again to the same frequency as the QAM carrier and select the NOISE marker mode The noise power density N is indicated by the analyzer To refer N to the channel bandwidth Bc of the DVB channel used the noise power N is to be calculated as follows 10lg Bc N 10lg channel bandwidth Hz dB dBm From th
185. sage with a number between 200 and 300 describing the error in greater detail see Appendix B Error Messages will be entered into the Error Queue 5 Command Error This bitis set if an undefined command or a command with incorrect syntax is received An error message with a number between 100 and 200 describing the error in greater detail see Appendix B Error Messages will be entered into the Error Queue 6 User Request This bit is set upon pressing the LOCAL key ie when the instrument is switched to manual control 7 PowerOn This bitis set upon switching on the instrument STATus OPERation Register The CONDition part of this register contains information on the operations currently performed by the instrument and the EVENt part on the operations performed by the instrument since the last readout of the register The register can be read by the queries STATus OPERa tion CONDition or STATus OPERation EVENt Table 3 4 Definition of bits used in the STATus OPERation Register Bit No Definition This register is not used STATus QUEStionable Register This register contains information on question able device states These may for instance occur if the instrument is operated out of specifications The register can be read by the queries STATus QUEStion able CONDition or STATus QUEStionable EVENt DDS200 Digital Demodulation System User Manual 3 25 Remote Control 3 26 Use of the Status Repo
186. set and enabled in the Event Status Enable Register Setting of this bit denotes a serious error which can be specified in greater detail by querying the Event Status Register DDS200 Digital Demodulation System User Manual 3 23 Remote Control 3 24 Table 3 2 Definition of bits in the Status Byte Register Cont Bit No Definition 6 MSS Bit Master Status 5 ummary Bit This bitis set if the instrument causes a service request This is the case if one of the other bits of this register is set together with its mask bitin the Service Request Enable Register SRE 7 OPERation Status Register Summary Bit This bitis set if an EVENt bit is set in the OPERation Status Register and the associated ENABle bit is setto 1 A set bit denotes that an action is just being performed by the instrument Information on the type of action can be obtained by querying the OPERation Status Register IST Flag and Parallel Poll Enable Register PPE Similar to the SRQ the IST flag combines the complete status information in a single bit It can be queried by Parallel Poll see page 3 27 or by IST The Parallel Poll Enable Register PPE determines which bits of the STB affect the IST flag The bits of the STB are ANDed with the corresponding bits of the PPE bit 6 in contrast to the SRE being used too The IST flag is obtained by ORing all results together The PPE can be set by the command PRE and read by the query PRE Eve
187. stical evaluation specified value is completely independent of all others Using suitable computation a value can be completely separated from the effects of other values The signal to be measured should comprise a minimum of errors phase error amplitude imbalance carrier suppression so that available margins are free for disturbances for example noise that cannot be avoided A list of parameters is given in Table 2 3 Provided the listed parameters do not occur at the same time the set limit values should not be exceeded to afford useful transmission In the case of combined parameters limits are correspond ingly reduced As the variety of combinations is almost infinite no values can be specified for such a case Specified values are based on experience simulation and measurements on the QAM modulators DDS200 Digital Demodulation System User Manual Manual Operation Table 2 3 Suitable limit values for QAM parameters Phase ripple Amplitude Discrete and and PE in the ripple and Alin Intermodulation general Order C N for BER passband range the passband products interference Linearity 3rd of QAM lt 104 max range max max and CS max order mode 27 dB 27 dB dB 16 34 dB 34 dB 1dB 32 37 dB 37 dB lt 0 5 dB 64 40 dB 40 dB 03 dB 128 21 5 dB 1 5 t 0 15 dB 43 dB 43 dB 0 2 dB 256 30 5 dB t 0 1 dB 46 dB 46 dB 0 1 dB Conditions 1 Abbreviations PE phase
188. t panel RF connector on the DDS200 is selected with a 75 2 termination This is indicated by the display INPUT 75 OHM FRONT on the left of the highlighted RECEIVER menu box INPUT RF CHRHHEL RF LEVEL 42 220 HHz zZ 14 5 dBu IHPUT 75 OHM FRONT NL RECEIVER ATTEN Figure 2 4 INPUT menu Feed the RF input signal into the RF connector located on the front panel to the right of the contrast control for the LCD display Refer also to RF in Table 1 1 on page 1 4 RF 6 S DDS200 Digital Demodulation System User Manual 2 5 Manual Operation Press the RECEIVER ATTEN soft key to match the input attenuation to the signal feed This provides access to another submenu in which the following can be selected via the AUTO soft key IHPUT RECEIVER ATTENUATION SET RF RF LEVEL 330 000 HHz 66 7 dBu AUTO AUTO LOW HOISE AUTO ATTENUATION O dB LOM DIST AUTO LOWEST DIST MANUAL 1 dE PREAMP Figure 2 5 INPUT RECEIVER ATTENUATION menu Setting the RF Frequency Press the Main Function RF hard key to display the RF menu MAIN FUNCTION MODE MEASURE 7 VLLL INPUT SETUP RF o z s STATUS C ALARM Enter a frequency via the numeric keypad Confirm the frequency using the ENT Enter key of the cursor keypad The entry is accepted only if the frequency value is wit
189. talling the product so it has proper ventilation Terms in this Manual These terms may appear in this manual WARNING Warning statements identify conditions or practices that could result in injury or loss of life CAUTION Caution statements identify conditions or practices that could result in damage to this product or other property Terms on the Product These terms may appear on the product DANGER indicates an injury hazard immediately accessible as you read the marking WARNING indicates an injury hazard not immediately accessible as you read the marking CAUTION indicates a hazard to property including the product Symbols on the Product The following symbols may appear on the product A AN m WARNING Protective Ground CAUTION Double High Voltage Earth Terminal Refer to Manual Insulated DDS200 Digital Demodulation System User Manual Preface This manual is divided into sections The sections contain the following information Section 1 describes the front and rear panel controls of the DDS200 Digital Demodulation System Section 1 also provides information about operating the digital demodulation system for the first time In addition it contains a brief description of the external interfaces and the units that can be connected to them Section 2 describes the basic manual operation of the digital demodulation system explaining how to use the hard and soft keys to control the unit This sect
190. the command for reading the output unit for example FREQ and fetching this value Command Sequence and It is evident from the discussions above that overlapping execution is possible Command with all commands Setting commands within a command line are not necessari Synchronization ly executed in the sequence that the commands are received To ensure that commands will be executed in a certain sequence each command must be sent in its own command line with an IBWRTO request To avoid overlapping execution of commands one of the commands OPC OPC or WAI must be used three commands have the effect that a certain action will only be triggered after the hardware has been set and has settled By suitable programming the controller can be forced to wait for the respective action see Table 3 1 Table 3 1 Synchronization with OPC OPC and WAI Command Action after hardware settling Programming of controller OPC Setting the Operation Complete bitin Setting bit 0 in the ESE the ESR Setting bit5 in the SRE Waiting for service request SRQ Writing a 1 into the output buffer Addressing the device as a talker WAI Continuing the IEC IEEE bus hand Sending the next command shake An example of command synchronization is given in Appendix D Program Examples 3 18 DDS200 Digital Demodulation System User Manual Remote Control Status Reporting System The status reporting system stores all
191. the device DDS200 Digital Demodulation System User Manual C 5 Appendix C List of Error Messages Table C 3 Execution errors Cont Error number 241 250 Test displayed upon an error queue query Explanations Hardware missing The command cannot be executed because of missing device hardware Example an option is not installed Mass storage error Error in the mass storage 251 252 253 Missing mass storage The command cannot be executed because of missing mass storage Example an option is not installed Missing media The command cannot be executed because of a missing data media Example no disk in drive Corrupt media Data media is corrupt Example wrong format of a disk 254 255 256 Media full Data media is full Example no room on the disk Directory full The media directory is full File name not found The specified file name cannot be found 257 File name error The file name is in error Example attempt to copy to a duplicate file name 258 260 261 Media protected The data media is protected Example the disk has a write protect tab Expression error The command contains a faulty mathematical expression Math error in expression The expression contains a mathematical error Example division by zero 270 271 212 Macro error Error in the execution of a macro Macro syntax error The macro definition co
192. the rear panel Proceed as follows 1 Power off the unit and disconnect all external connections especially the AC supply connector Remove rear blue feet two screws each Push the covers top and bottom to the rear and remove them Remove the four Phillips screws at the left and right on the side Fold down the rear panel assembly Install the option according to the instructions that are packaged with it Reassemble the unit in reverse order Do a software update if necessary see page 1 13 D RE c i S v c Perform a test according to the enclosed instructions and the functional test described in Functional Test on page 1 15 The DDS200 has a Centronics printr interface connector X32 on the rear panel The 25 pin D type female connector is PC compatible The type of printr can be selected in the setup menu refer to printr Menu Selecting the Type of printrs on page 2 23 The HARDCOPY key makes a print out of the current display Commercial PC printr cables can be used for connecting the DDS200 to the printr The unit is provided with a serial RS232 interface connector X33 on the rear panel Via this interface the unit can be remote controlled from a PC A firmware update can also be carried out via the RS232 interface For detailed information about configuring the interface refer to RS232 Menu Setting the RS232 Interface Parameters on page 2 22 The remote command set is explained in
193. the standby key The green power on LED lights up and the display back lighting is also on T 21 no 100 120V 2 5A 220 240V 1 3A AUTOMATIC VOLTAGE SELECTION O O F1 F2 IEC 127 T3 15 H 250 V 50 60 Hz G3 The following operations take place during switch on m LED test W Power on display that specifies the unit designation and firmware version refer to the following example TV TESTRECEIVER EFA FIRMWARE VERSION V2 02 2 1 96 12 00 DATE 2 1 96 TIME 12 00 IEC 625 IEEE488 BUS ADDR 6 RS232 9600 8 N 1 m Status display listing installed hardware assemblies W Measurement display MEASURE menu the unit is now ready for operation Observe error messages if any during the power on process DDS200 Digital Demodulation System User Manual Preparation for Use NOTE When powering on the unit for the first time the factory default settings are loaded The unit can also be reset to the default settings with a preset in the PRESET menu During start up all hardware modules are tested briefly and checked for their presence In addition all relays are actuated input attenuator Setting the Contrast of the The built in LCD display has a limited viewing angle It can be vertically Display adjusted within certain limits and optimally adapted to the working conditions Setting is by perfo
194. tic Compatibility when it is used with the product s stated in the specifications table Refer to the EMC specification published for the stated products May not meet the intent of the Directive if used with other products FCC Compliance Emissions comply with FCC Code of Federal Regulations 47 Part 15 Subpart B Class A Limits EC Declaration of Conformity Low Voltage Approvals Installation Category Descriptions 4 Compliance was demonstrated to the following specification as listed in the Official J ournal of the European Communities Low Voltage Directive 73 23 EE C Amended by 93 68 EEC EN 61010 1 1993 Safety requirements for electrical equipment for measurement control and laboratory use UL3111 1 Standard for electrical measuring and test equipment CAN CSA C22 2 No 1010 1 Safety requirements for electrical equipment for measurement control and laboratory use Terminals on this product may have different installation category designations The installation categories are CAT III Distribution level mains usually permanently connected Equipment at this level is typically in a fixed industrial location CAT II Local level mains wall sockets Equipment at this level includes appliances portable tools and similar products Equipmentis usually cord connected CATI Secondary signal level or battery operated circuits of electronic equipment DDS200 Digital Demodulation System User Manual Ap
195. ticularly important when the instrument is to receive signals that are not coded to MPEG 2 standard DDS200 Digital Demodulation System User Manual 2 37 Manual Operation 2 38 ALARM Menu This subsection comprises the following topics Configuring the Alarm Register page 2 38 Alarm Register page 2 39 Setting Limit Values page 2 41 Statistics page 2 41 Printing the Register page 2 43 Clearing the Register page 2 45 When lighted the LED next to the ALARM key signals that at least one new alarm message has been registered since the register was called up last The LED turns off when the alarm register is called up with the ALARM key Configuring the Alarm Register Any of the alarm messages can be disabled so that it is not entered into the alarm register To do so press the ALARM key in the MAIN FUNCTION block and then the ALARM CONFIG soft key The menu shown in Figure 2 31 is displayed DAH ALARH CONFIG SET RF RF LEVEL 330 000 HHz 66 7 dBu DISAELED MPEG DATA Figure 2 31 ALARM CONFIG menu By pressing the respective key each one of the alarm modes can be individually configured If an alarm should not be signalled select DISABLED Another keystroke switches back to ENABLED Any change of the configuration is stored in the alarm register If an alarm is disabled the DDS200 enters in the respective column An enabled alarm is indicated by DDS200 Digital Demodulat
196. tion due to 3rd order nonlinearity 2 78 DDS200 Digital Demodulation System User Manual Table of Contents Figure 2 60 Setup for external BER measurement 2 80 Figure 2 61 BER as a function of C N ratio 2 83 Figure 2 62 Effect of receive filter on C N value C Nrec C N after receive filter C NC C N ahead of receive filter in channel 2 84 Figure 2 63 Assignment of parallel MPEG data interface X31 06 626 5 Bee Rois RU ee a y RR 2 86 Figure 2 64 Signals at parallel interface in 188 byte mode STATUS SER PAR MPEG FRAME SIZE 2 87 Figure 2 65 Signals at parallel interface in 204 byte mode STATUS SER PAR MPEG FRAME SIZE 2 87 Figure 2 66 Cascading of two 0052005 2 88 Figure 3 1 Tree structure of SCPI command system using SENSeasanexample 3 6 Figure 3 2 Instrument model with remote control via IEC IEEE DUS bibs nate OR dee 3 16 Figure 3 3 Status Register Model eee 3 19 Figure 3 4 Overview of status registers eere 3 22 Figure F 1 Transmission of character in 7 bit ASCII code even parity 2stop bits 1 0 0 cc cc cece cece eens rrt F 3 Figure F 2 Wiring for software handshake F 6 Figure F 3 Wiring for hardware handshake 7 DDS200 Digital Demodulat
197. to LOCAL switchover can be disabled by the control character lt CTRL L gt OC hex sent via the RS 232 interface In this case switchover to manual operation is only possible via the RS 232 interface LLO is displayed on the screen Lock out of the LOCAL switchover can be cleared by sending Ctrl L gt 0C hex again via the RS 232 C interface DDS200 Digital Demodulation System User Manual F 1 Appendix F Remote Control via RS 232 C Interface Set device to manual operation via RS 232 C interface v24putc port 0x12 Characteristics of Interface Signalling Lines F 2 W Serial data transmission in asynchronous mode m Bidirectional data transmission via two separate lines Transmission rate selectable between 1200 and 19200 bauds m Signal level logic 0 from 3 to 15 V m Signal level logic 1 from 15 to 3 V m Connection of external device controller possible m Software handshake XON XOFF m Hardware handshake RTS CTS Table F 1 Pin assignment of RS 232 C interface Signal Line 1 54321 2 STE 3 unir UT Ox 5 HP l 9876 7 8 9 RxD Receive Data Data line transmission from controller to EFA TxD Transmit Data Data line transmission from EFA to controller DDS200 Digital Demodulation System User Manual Appendix F Remote Control via RS 232 C Interface DTR GND DSR RTS CTS Transmission Parameters Data terminal ready
198. trument Model and Command Processing 3 16 Input Unit D ie tk ok RLW CUI SCENE SPON 3 16 Command 1 3 16 Data Set and Device Hardware 3 17 Status Reporting System eee 3 17 Output Unit shea Nese tees ae eR UE CEDE NES 3 18 Command Sequence and Command Synchronization 3 18 Status Reporting System 3 19 Structure of a SCPI Status Register 3 19 Overview of Status Registers 3 22 Description of Status Registers 3 23 Use of the Status Reporting 3 26 DDS200 Digital Demodulation System User Manual Table of Contents Resetting the Status Reporting System 3 28 Maintenance and Troubleshooting Maintenance 1 eoe thse atch ee ead ee ded et bd de 4 1 Troubleshooting si oerte et ee oe ERE 4 2 Self Test QAM uus Knit eben Meade 4 3 Appendices Appendix A A 1 Appendix B IEC IEEE Bus Interface ee B 1 Interface Characteristics 0 eee cette e B 1 Bus eine ML EET B 1 Inte
199. umeric keypad VARATION The cursor keypad also contains the keys ESC ENT and CLR m Use the ESC key to return to a submenu refer to Soft Keys on page 2 12 m Use the ENT key to confirm a numerical entry refer to Numeric Keypad on page 2 14 m Use the CLR key to erase a numerical entry refer to Numeric Keypad on page 2 14 DDS200 Digital Demodulation System User Manual 2 13 Manual Operation 2 14 Numeric Keypad Selecting Settings Selected parameters can be directly modified via the numeric keypad in contrast to the cursor keys Enter the value with the numeric keys and confirm it with the ENT key on the cursor keypad refer to Cursor Keys on page 2 13 If a correction is necessary during entry the figure in front of the cursor can be erased or overwritten with the CLR key on the cursor keypad For this purpose the cursor can be shifted with the keys 4 and from the end to the required position DATA B M 7 8 9 4 5 6 1 2 3 0 VY M M This entry facility is for making modifications that otherwise can only be made stepwise with the cursor keys NOTE The entry is terminated after it has been confirmed with the ENT key Erroneous entries are rejected and do not modify the previously set value In most cases settings are performed by selecting a menu via the MAIN Function hard keys The required setting is selected by pr
200. us NOTE The PLL configuration also affects the serial output for external BER measurements X6 and X5 If the serial MPEG data interface X7 is mainly used the PLL should be switched off If it is on incorrect BER measurements or loss of synchronization may occur at low temperatures or immediately after the instrument has been powered up SER PAR MPEG DATA FRAME SIZE With the aid of this key a selection can be made whether the serial and parallel MPEG outputs should use the whole information including the 16 error protection bytes per frame for data transmission or whether only the 188 relevant data bytes should be transmitted This makes no difference for the error protection function However some of the MPEG decoders accept only one data format The MTD200 MPEG Test Decoder can handle both formats and switch over is automatic The 188 byte mode is preferred for the MTD200 MPEG Test Decoder For more detailed information refer to Assignment and Functions of Parallel and Serial MPEG 2 Outputs on page 2 85 I Q INVERSION The DDS200 continuously monitors the transmitted data stream for MPEG 2 sync words If a synchronization is not possible the instrument inverts the I and Q data streams and restarts the procedure provided AUTO has been selected With NORMAL and INVERTED this automatic switch over can be disabled and the signal decoded in the normal or the inverted mode NOTE Switching off the automatic function is par
201. used slots are automatically identified They are displayed in italics and cannot be selected When the internal noise generator is active refer to MEA SURE Menu on page 2 46 the noise power is automatically increased so that a constant noise level is obtained in the selected filter bandwidth SYMBOL RATE The SYMBOL RATE soft key is used for configuring the symbol rate of the QAM demodulator The rate is calculated from the net data rate D according to the formula 204 1 188 log M Symbol Rate D with M being the order of QAM M 4 16 32 64 128 256 The factor of 204 188 15 the result of the Reed Solomon error protection This can be seen in the following diagram DDS200 Digital Demodulation System User Manual 2 31 Manual Operation 4QAM 16QAM 32QAM 64QAM 128QAM 256QAM Symbol SR in MSPS 4 0 10 20 30 40 50 Net data rate D in Mbit s Reed Solomon 204 188 To ensure proper function of the instrument the symbol rate has to be accurately set Refer to Figure 2 28 DOAN STATUS SYNBOL RATE SET RF RF LEVEL 330 000 HHz 66 7 dBu SYMBOLRATE SYNC el MSPS AUTO SEARCH STOF AUTO SEARCH Figure 2 28 STATUS SYMBOL RATE menu Press the SYMBOL RATE VALUE soft key and enter a value between 1 5 and 7 0 MSPS mega symbols per second The value should be accurate to within three decimal digits 2 32 DDS200 Digital Demodulation System User Manual Manual Operation If the
202. ust be adjusted This is done by using only the last value stored for calculating the BER or by carrying out an integration over 10 100 or 1000 measured values In BER calculation the unit automatically switches to a longer integration time if this is expedient The unit switches back automatically to a shorter integration time if this is desired by the user You can define a minimum number of BER samples to be taken in a measure ment If 1000 samples are selected for example the test receiver operates exclusively in the 1000 sample mode This also means that sufficient time must be allowed for a measurement to obtain a useful result A very stable indication is obtained with this mode which is suitable especially for stationary applica tions where the operating conditions for the demoduator remain the same If a minimum integration time of 1 sample is selected the receiver switches the measurement time to 1 sample when a high BER gt 1E 6 is measured In calibration for example this allows a change of the BER value to be detected immediately however the indication is relatively unstable due to the short measurement time In practice a minimum integration time of 10 samples has proven expedient for normal applications Information on the status of integra tion is useful especially with a high number of samples Two figures are therefore specified together with the BER value The first figure indicates the number of samples actually use
203. ust be determined The four outer corners of the constellation diagram are assessed since this is where phase jitter has the strongest effect Now the frequency distribution is determined for each decision field along the four circular paths farthest away from the center point which is the coordinate origin of the constellation diagram Here too the standard deviation opjy N can be calculated which is in addition affected by noise The effect of a sinusoidal interferer which may be present at the same time is eliminated by way of calculation prior to determining the RMS phase jitter According to the addition theorem of the Gaussian distribution the following applies _ 2 On The RMS phase jitter can thus be obtained by means of trigonometric conversion With an ideal QAM signal all measured I Q values lie exactly in the centers of the decision fields If a signal is distorted eg through amplitude imbal ance a phase error or a residual carrier the measured I Q values will not be in the centers of the decision fields but still concentrated on a single point in each field The measured values are available in discrete form as a result of digital processing of the I Q coordinates The resolution of the measured values can be considerably increased by superimposing a small noise component SNR 45 dB on the signal to be analyzed and using the method described above forming an average over several discrete values and
204. ut of transmitted data Parallel MPEG 2 interface W Serial MPEG 2 interface W Serial interface The serial interface is described on page 2 80 and is not suitable for the output of transmitted MPEG 2 data In this section the other two interfaces are described They were internationally standardized by the DVB TM Ad Hoc Group Physical Interfaces For both interfaces you can select if the 16 error protection bytes are to be transmitted in addition to the 188 data bytes of the 2 frame yielding a total of 204 bytes The selection is made in the STATUS SER PAR MPEG FRAME SIZE menu The parallel MPEG 2 interface X31 operates according to the LVDS low voltage differential signaling standard which provides symmetrical data DDS200 Digital Demodulation System User Manual 2 85 Manual Operation 2 86 The key characteristics are Source impedance 100 Q DC component 1 25 V Signal amplitude 247 to 454 mV Maximum length of transmission link approximately 5 meters The parallel interface has the following assignment front view 131211 1 a A w rn Figure 2 63 Assignment of parallel MPEG data interface X31 Table 2 8 Assignment of parallel MPEG data interface Noninverting output Inverting output Signal pin number pin number Clock 1 14 GND 2 15 DATA 7 3 16 DATA 6 4 17 DATA 5 5 18 DATA 4 6 19 DATA 3 7 20 DATA 2 8 21 DATA 1 9 22
205. values are shifted to the left by 0 441 dB DDS200 Digital Demodulation System User Manual Manual Operation If the BER has been determined for a given C N value this rate can be used for indicating various parameters defined by the DVB Measurement Group This definition of parameters allows direct comparisons to be made between different test systems and is of international relevance The two most important parame ters are briefly explained below for a C N ratio with a BER of 1E 4 and with the two corrections of the C N value described above already made m Equivalent noise degradation END The equivalent noise degradation is a measure of the transmission loss of the complete system from the modulator via the cable link to the demodulator The equivalent noise degradation indicates the deviation of the real from the ideal C N ratio in dB for a BER of 104 In practice values of approx 1 dB are obtained W Noise margin The noise margin is understood to be the difference between the C N resulting in a BER of 104 and the C N value of the cable system actual C N For measuring the C N of the cable system the symbol rate of the QAM signal is taken as the noise bandwidth The following values are obtained for the example shown in Figure 2 61 for 64QAM Equivalent noise degradation 1 6 dB Noise margin 12 0 dB Assignment and Functions of Parallel and Serial MPEG 2 Outputs The DDS200 has three different interfaces for the outp
206. ve data When block data are transmitted software handshake is impossible due to the above reasons DDS200 Digital Demodulation System User Manual F 5 Appendix F Remote Control via RS 232 C Interface Local controller For software handshake the DDS200 must be connected to the controller connection for Software according to the following wiring diagram which is applicable to controllers Handshake with 9 pin or 25 pin connectors 005200 Controller DDS200 Controller 9 pins 9 pins decoder pin Signal pin 1 5 2 RxD TxD 3 3 TxD RxD 2 O o 5 GND GND 5 9 e O 5 9 pepe Controller 005200 Controller 9 pins 25 pins i decoder pin Signal pin o gt 2 RxD TxD 3 dE 3 TxD RxD 2 5 GND GND 7 O O O O O O O O oO O Oo Oo Figure F 2 Wiring for software handshake Hardware Handshake In the case of hardware handshake the DDS200 signals via the RTS lines that it is ready to receive data A logic 0 active signifies ready a logic 1 means not ready Via the CTS line the controller informs the DDS200 that it is ready to receive data A logic 0 activates data output whereas a logic 1 commands the DDS200 to stop data transmission The DTR line remains active logic 0 until the serial interface is switched for remote control F 6 DDS200 Digital Demodulati
207. xt to be modified The required character can be selected by means of cursor keys 4 and and inserted in the entry line with the GETCHAR soft key The cursor automatically moves to the next position If a character is to be inserted in the text the cursor can be moved to the position using the RIGHT and LEFT soft keys Insert a new character inserted by pressing the GETCHAR soft key A character in front of the cursor can be erased by means of the DELCHAR soft key 5 RF EDIT TEXT RF RF LEVEL 42 220 HHz 83 3 dBu RIGHT MEMORY TERT LEFT GETCHAR USE CURSORKEYS TO SELECT DELCHAR EHTER Figure 2 10 RF STO RF EDIT TEXT menu The entry is terminated by pressing the ENTER soft key DDS200 Digital Demodulation System User Manual 2 15 Manual Operation Presetting the Unit The PRESET key restores the factory set default setting PRESET RF CHAHHEL RF LEVEL STANDARD 45 250 MHz 2 113 2 dBu BG o PRESET FIRMWARE W202 13 09 1995 17 59 57 NEN IEC 625 ITEEE488 PRESET OAM 00 8 1 E PRIHTER EPSON COMPATIBLE TESTING SYSTEM HO ERROR FOUND SERVICE Figure 2 11 PRESET Menu Types of presetting the unit m PRESET Preset for the whole unit m PRESET QAM Preset for the QAM demodulator mode PRESET RF CHRHHEL RF LEVEL STANDARD 45 250 MHz 2 79 3 dBuV B G 15 01 96 FIRMWARE 08 11 18 v2 02 13 03 1985 17 59 57 IEC 625 TEEE488 9600 8 H 1 PRIHTER EP
208. ystem D 6 interface messages 3 4 MEMory subsystem D 11 overlapping commands 3 18 overview 3 1 parameters 3 9 programming examples E 1 queries 3 9 READ subsystem D 12 return to manual control 3 3 ROUTe subsystem D 5 SCPI standards 3 11 SCPI structure and syntax 3 5 SENSe subsystem D 7 status reporting system 3 17 STATus subsystem D 2 SYSTem subsystem D 4 UNIT subsystem D 11 Resetting status reporting system 3 28 RF frequency setting 2 6 Roll off factor 2 35 ROUTe commands D 5 RS 232 1 7 RS232 1 12 hardware and software handshake F 5 interface F 2 interface functions F 4 transmission parameters F 3 RS232 interface description 1 16 S S N ratio 2 69 SAW filter 2 31 SCPI introduction 3 5 status register 3 19 SCPI error messages C 1 SCPI standard remote control 3 11 Selecting the input procedure 2 4 Selecting the mode procedure 2 3 Selftest QAM 4 3 Sending device settings programming example E 2 SENSe commands D 7 SERBUS 1 6 Serial data frame size 2 37 Serial interface RS232 1 16 Serial poll 3 26 Service request programming example E 4 Service request SEQ 3 26 Setting contrast 1 13 Index 3 Index Setting device address 3 2 Setting menus procedure 2 10 Setting the RF frequency procedure 2 6 Settings general device 2 19 storing 2 17 Soft keys description 2 12 Spectrum display coefficients 2 56 STATus commands D 2 Status

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