NC804 Manual
Contents
1. break point insure receiver audio quality perform input level measurements and make sure that break ORANGE 3 point connections are NOT made between the discriminator and CTCSS or SQUELCH circuitry or any other RX AUDIO type of decoder if installed and in a location so not to interrupt an internal D C bias voltage in the receiver s audio stages NOTE Because of filtering circuitry both CTCSS and carrier SQUELCH signals will not pass through scrambler DTMF and other in band decoders may fail to function because of signal inversion and level changes If it is necessary to connect to audio path after CTCSS decoder make sure to bypass or disable the CTCSS High Pass Filter if used The NC804 contains a high pass filter to filter out CTCSS tones Refer to Figure 5 page 6 for typical circuit configuration NC804 REV E 04 04 3 RX LEVEL TEST PROCEDURES To determine receiver input level select clear mode and connect an oscilloscope or A C rms voltmeter to the solder junction of RX AUDIO INPUT BLUE LEAD 6 and circuit break point in discriminator Using a service monitor generate a full quieting signal modulated with a 1KHz tone at full system deviation then measure signal level Use this measurement to select from RX GAIN CHART the appropriate resistor values for R1 and R6 Refer to Figure 3 page 5 for location of R1 and R6 NOTE Verify that2. for conventional operation as noted in the instruction manual Reprogramming the NC804 is accomplished using the Model NC800 Programmer via direct connection to a standard serial port and loading the Windows 95 98 NT compatible software then simply following the on screen menu select user desired operating parameters and key codes The NC800 software is a very intuitive and easy to use program with context sensitive help pertaining to every aspect of programming just a mouse click away Once the Model NC804 scrambler module has been programmed it can then be used while still connected to host P C and transceiver as a RF modem to perform Over The Air Kill Function OTAK to disable radio if stolen or lost only available in version 1 24 and higher PACKET SYNCHRONIZATION DELAY In scramble mode the NC804 transmits a 60mS synchronization data burst at the beginning of each transmission and is repeated every one 1 second This data provides no key code information but is required for proper operation and support of late entry reception Depending on the type of radio system a data synchronization delay may be required This is due to the response time between activation of transmit PTT and speaker audio at receiving point Care must be used in determining this delay as time will vary from system to system For dependable cipher operation the NC804 must wait for this time period prior to sending packet data sequence As an e
3. the RX AUDIO OUTPUT ORANGE LEAD 3 has near the same level measured at input RX GAIN LEVEL CHART INPUT BLUE WHITE 12 Connect these two leads directly in series with the transmitter s microphone and modulator circuitry MIC AUDIO INPUT Determine first if the microphone is D C biased by measuring for a voltage potential across the microphone amp element If the microphone is D C biased the leads must be connected between the bias circuitry and BLACK WHITE 1 FIRST microphone amplifier stage as the NC804 will not pass bias voltage In some cases the removal of a MIC AUDIO OUTPUT resistor or coupling capacitor makes for an ideal circuit break point To insure transmit audio quality perform input level measurements and make sure that break point connections are made BEFORE the transmitter s PRE EMPHASIS or LIMITER circuitry and in a location so as to NOT interrupt any internal D C bias voltage in the modulator audio stages Refer to Figure 5 page 6 for typical circuit configuration MIC LEVEL TEST PROCEDURES To determine microphone input level select clear mode and connect an oscilloscope or A C rms voltmeter to the solder junction of MIC AUDIO INPUT BLUE WHITE INPUT LEAD 12 and circuit break point in modulator Key transmitter and speak loudly into microphone or with an acoustically coupled 1KHz audio tone not exceeding 2 3 system deviation then measure the signal level Use thi
4. ECT pushed Reconfigure in software for DOUBLE TAP MODE This feature eliminates the need for a software or DOUBLE TAP MODE METHOD 2 SPST switch sometimes not available in today s portable radios Using this feature allows the user to toggle between scramble and clear modes by simply pushing the radio s monitor switch TWO times in rapid succession Double tapping The NC804 generates a 900 Hertz tone output to the radio speaker responding with TWO beeps to indicate selection of scramble mode and ONE long beep for clear mode WHITE GREEN 5 METHOD 1 This output is current limited by a 1K ohm resistor and will source 2 5 volts at 3mA when in the VISUAL INDICATOR METHOD 1 scrambled mode Connect this lead to the ANODE of a high efficiency LED and the CATHODE of the LED to ground NOTE For sinking to ground reconfigure in software for sinking Many radios have spare indicators such as Busy Monitor Call Aux Back lighting etc that can be used for this option Refer to Figure 5 page 7 for typical circuit configuration WHITE GREEN 5 METHOD 2 When configured via the NC800 programmed this output works in conjunction with the audio RX AUDIO ENABLE METHOD 2 beep output GREEN lead to enable the receivers audio output amplifier during the DOUBLE TAP or BEGIN TO SPEAK BEEP tone generation This output can be configured to sink or source external circuitry Refer to radio s service manual to deter
5. FAX 530 477 8403 DATA SIGNALING PRODUCTS SALES 800 874 8663 e mail tech norcommcorp com web www norcommcorp com 15385 CARRIE DRIVE GRASS VALLEY CA 95949 530 477 8400 reo tne 0 tat MODEL NC804 VOICE ENCRYPTION SCRAMBLER INSTRUCTION MANUAL INTRODUCTION The Model NC804 is a micro miniature voice plus pseudo random rolling code scrambler designed to provide high level security for two way radio voice communication systems It s unique digital encryption processing algorithm plus it s many features makes the Model NC804 a perfect cost effective solution for high end voice encryption scrambling for commercial users police departments public safety organizations and other systems as a defense against unauthorized interception of private and sensitive voice transmissions by casual or even the most determined listeners The Model NC804 features 8 user key codes with over 20 trillion codes to choose from Single line or double tap mode for selection of scramble or clear function audible speaker beeps or LED visual outputs of mode selection and start to speak sequence over the air kill disable for stolen or lost radios six programmable operating features and 4 layer SMT assembly Measuring 0 90 W x 1 30 L x 0 22 H the Model NC804 supports limited space applications and is plug compatible in most applications with our popular Model NC802 voice inversion scrambler making it ideal for syste
6. PERATING OPERATING CURRENT OPERATING TEMPERATURE SIZE erie Me MOUNTING 1 SYSTEM PROGRAMMING 1 1ms average 300Hz to 2800 2 Adjustable from 3 5 to 710mV rms gt 50K ohms D C blocked Adjustable from 3 5 to 710mV rms lt 2K ohms D C blocked Typically less than 1dB Non volatile EEPROM Automatically detects scrambled mode 1 Sink or Source LED driver 2 Audible Beeps speaker driver 1 Single line active high or low 2 Double tap of momentary switch Active low to transmit 5 5VDC to 20VDC Less than 10mA 30 C to 70 C 0 90 W x 1 30 L x 0 22 H 22 85mm x 33 02mm x 5 6mm Double sided adhesive tape FOR TECHNICAL SUPPORT CALL 530 477 8402 Micro miniature header and 12 inch Teflon color coded cable assembly Model NC800 Windows based Programming software and RS 232 P C adapter SPECIFICATIONS ARE SUBJECT TO CHANGE IN THE INTEREST OF TECHNICAL IMPROVEMENT WITHOUT NOTICE OR OBLIGATION PROGRAMMING All Programming with the exception of input and output level settings are performed using the inexpensive Model NC800 P C Programming Adapter and Windows based software Unless otherwise specified the Model NC804 scrambler functional parameters and key codes come factory defaulted
7. WVYOS 1 TIVLSNI LON OG ___ YOLVNIANTHOSIO 7 ranveos HOLIMS HOLINOW Z 1 Yo HOLIMS 1 6 405 i SLIHM MOTIAA ania AYLINOUIO 5 YOLVOIGNI 405 34 94 NC804 REV 04 04 WARRANTY POLICY NorComm products are unconditionally guaranteed for two 2 years on materials and labor from date of purchase All Warranty repairs must be performed at NorComm s Customer Service Department in Grass Valley CA Units under warranty can be returned for repair or replacement without prior authorization however a letter explaining the defect should be enclosed with the unit Out of warranty units returned constitute Purchaser s authorization for to repair or replace equipment and to invoice Purchaser for any and all reasonable costs of repair labor parts and freight shall not be obligated to repair or replace equipment rendered defective in whole or in part by causes external to the equipment such as but not limited to catastrophe power failure or transients environmental extremes improper use and maintenance or interfacing applications NorComm further assumes no liability for any incidental or consequential damages which may result from the applications of its products by the Purchaser or any other party NC804 REV E 04 04 8
8. m upgrades OPERATION The Model NC804 scrambles speech by transposing the inband voice spectrum into alternative frequencies This is accomplished by a proprietary digital encryption algorithm that pseudo randomly changes the rolling code sequence frequency generator an average of 1000 times second with an average dwell time of 1 1 milliseconds The NC804 is continuously churning it s data comprised of the selected key code while waiting for either the reception of transmitted packet data or activation of the PTT function It is important to know that cipher keys are never transmitted but rather the unit s address and sync cue When scramble mode is enabled and the unit transmits it s packet data all units within the system compare the data to their own coded address If the address is the same deciphered reception is automatic Clear reception is also automatic Security of system depends on the secrecy of users code keys To maintain secure operation it is recommended that key codes be changed from time to time Reprogramming of key codes and other features requires the use of the inexpensive Model 800 Programming Adapter and Windows based software package NOTE Export of the Model NC804 is controlled by the U S Department of State Office of Defense Trade Control License to export this product is required by the United States Department of Commerce Itis the users responsibility to comply with all government regulations
9. mine sink or source compatibility to enable muted receiver s audio amplifier circuitry GREEN 14 Connect this lead directly to the high side of portable radio speaker to input of receiver s audio amplifier AUDIBLE BEEP through a series resistor The value of this resistor will have to be selected for desired audio output level This feature is used for Double Tap and Begin To Speak Beep Mode NOTE If connected to receiver s audio output amplifier refer to RX AMP ENABLE METHOD 2 BROWN 13 Connect this lead to transmit PTT circuitry that goes to ground during transmit mode PGISINBUT GRAY 8 These inputs provide binary selection of one of eight key codes If all inputs are left unconnected BINARY CODE SELECT B1 ungrounded key code one is defaulted Selection of the seven alternate key codes is accomplished with the WHITE 9 radio code selection or by use of a binary coded switch connected to the gray white and violet leads of BINARY CODE SELECT B2 cable assembly Refer to Figure 1 page 5 for Key Code selection VIOLET 7 BINARY CODE SELECT B4 BLUE 6 Connect these two leads directly in series with the output of the receiver s discriminator circuitry for optimum RX AUDIO INPUT recovered audio In some cases the removal of a resistor or coupling capacitor makes for an ideal circuit
10. regarding the use of this product SPECIFICATIONS FORMAT Rolling code encryption SECURITY High level CODE KEY 5 3 line binary selection of 8 key codes KEY CODES 6 Digit address over 20 Trillion code combinations Six 6 Digit Key Coded Address can be made up from any of the printable characters on the keyboard Note Lower case alpha keys are automatically default to upper case characters KILL To disable radio if stolen or lost ENCRYPTION Real time frequency domain SYNCHRONIZATION Allows late entry reception PACKET Programmable 100ms to 850ms PACKET 960ms NC804 REV E 04 04 1 PACKET DWELL TIME BANDWIDTH AUDIO INPUT _ AUDIO OUTPUT LEVEL INPUT OUTPUT MEMORY 02 CIPHERED RECEPTION SCRAMBLE 5 SCRAMBLE CLEAR ENABLE PTEINPUT iia ais O
11. s measurement to select from the MIC GAIN LEVEL CHART the appropriate resistor values for R2 and R5 Refer to Figure 3 page 5 for location of R2 and R5 NOTE Verify that the MIC AUDIO OUTPUT BLACK WHITE LEAD 1 has near the same level measured at input MIC GAIN LEVEL CHART 500 1000 175 350 1000 2000 350 710 200K 200K NC804 REV E 04 04 4 FIGURE 1 KEY CODE SELECTION CHART 1 LEAD NOT GROUNDED 0 LEAD GROUNDED DEFAULT KEY CODES FIGURE 2 PCB BOTTOM VIEW emus a 0000 000 Tuae 04 04 FUNCTIONAL BLOCK DIAGRAM DT Lay HOLIMS INdLno ALOWSY LINN gt yoswa To gt gt YATIONLNOD JOULNOD XLXY no SIN lt NI YYOMLAN any dWa 3d KID A F 4 21 4 5 193 JN 5 133 94 NI XY 34 913 NC804 REV 04 04 TYPICAL CIRCUIT CONFIGURATION NOILONNS TI 3718 FUVMLIOS NMOHS SV 31 JONVYO ALIHM LOANNOD ANY ANIT 35125 ILON 1 1 5 i F 55010 HOTANDS F 531035 NI l LINN YS TE
12. xample units talking through a repeater system may require 250 to 350mS delay This is typically 100mS for transmit PTT circuitry and 150 to 250mS for repeater CTCSS detect The NC804 is default programmed for 150mS delay and is adequate for direct operation no repeater The delay time can be user programmed from 150mS to 850mS in 100mS increments using the Model NC800 P C Programmer For some users it may be difficult to determine when to start to speak due to packet delay and can result in loss of the first part of voice message To accommodate this condition the NC804 can be programmed to provide an audible beep indicating Start To Speak NC804 REV E 04 04 2 INTERFACING As supplied the Model NC804 is fully adaptable for most applications It is however recommended that before final installation and for optimum performance that installation be performed by a qualified technician using the correct test equipment and that both transmit and receive audio input levels to the NC804 be measured independently and if necessary that the correct gain setting resistors be installed Refer to MIC and RX input interfacing procedures to determine input signal levels and selection of appropriate resistor values The use of a service monitor with audio generator and an oscilloscope or A C rms voltmeter is required for these measurements A piece of double sided adhesive tape is provided to eliminate the need for mounting hardware When scrambler is read
13. y for installation remove protective covering from one side of tape and attach to the bottom side of P C board Now remove protective cover from remaining side of tape and adhere scrambler to desired location making sure that mounting surface is clean and dry to insure positive mounting If possible scrambler should be located away from intense r f fields and all leads be kept to minimum lengths with unused leads removed from cable assembly NOTE Refer to Figure 5 page 6 for typical circuit configuration before installation RED 2 R E TT Connect to a 5 5 to 16VDC regulated D C source Because both receiver and microphone low level audio SUPPLY passes through the NC804 it is very important to use a quiet and stable D C voltage to reduce the possibility of introducing power supply noise that would alter these audio signals Connect to common TX and RX ground location Power supply noise and ground loops may result in TX or RX audio stages if ground return is not common to both YELLOW 11 METHOD 1 Connect this lead in series with a SPST switch to ground to radio s software switch providing SCRAMBLE CLEAR a logic to ground when programmed to enable scramble mode on a per channel selection DEFAULT METHOD 1 YELLOW 11 METHOD 2 Connect this lead to the radio s Monitor switch providing momentary closure to ground when SCRAMBLE CLEAR SEL
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