Users Manual FSK-9601
Contents
1. Hee 2 E ee o a a acera o l N PS a e e e e e o a 50 ee G eaa Ill e e x g 99 g ee ee e BHEHNHNEHNHNEHEEN g BEEBE Eee aun Copyright for and Software There exists a copyright for the FIR filter EPROM to SYMEK GmbH or UIf Kumm DK9SJ All other copyrights for schematics and board layout belong to SYMEK GmbH or Ulf Kumm Stuttgart The modem cannot be operated independently So it is a complex component and there is no need for a EMI certification CE sign When the modem is to be used in systems other than TNC3 or TNC31 the EMI regulations have to be observed The contents of this manual may be copied as long as the author and the source is mentioned Users Manual FSK Modem FSK9601 C Version 14 05 2005 Production and distribution SYMEK GmbH Datentechnik http symek com Address D 70597 Stuttgart Sonnenberg Johannes Kramer StraBe 34 Phone 49 711 76 78 923 Fax 49 711 76 78 924 e mail info symek com FSK 9601 Page 92. 96 1913 98 J13 J10 J5 J12 14 J4 J12 1228 915 96 1915 98 915 910 5 14 J15 J12 Xtal oscillator 19 6608 MHz instead of 9 8304 MHz Xtal oscillator 39 3216 MHz instead of 9 8304 MHz Test pins on modem FSK9601 You can access three test pins on the bottom side of the modem board MP1 RX Eye AF signal at the decider comparator input Connect an oscilloscope to check the receiver eye diagram s an MP2 TX Eye Transmit signal at the D A converter output unfiltered transmit eye diagram Check the transmit eye before the antialiasing filter and modulation amplitude trimmer MP3 PTT MP3 is LOW 0 Volt in receive mode HIGH 5Volt in transmit mode Setting the Baudrate with FSK9601 The FSK9601 is available for various baudrates from 1000 Baud to 1 228 kBaud baudrates of transmitter and receiver can be configured to be different For setting the baudrate it is necessary to select the frequency of the master clock oscillator set the frequency dividers with the solder jumpers J2 to J15 select the component values of the analog transmit and receive filters according to the baudrates Changeing the baudrate requires tools for smd part soldering and experience in handling such miniature parts We do not recommend to change the baudrate We shall publish the instructions for changeing baudrate on http symek com later Known problems A white n
3. TRX4S Kenwood Yaesu Azden etc TRX4S TM733 TM455 TM251 TM451 TM V7E Azden PCS9600 Yaesu FT8500 etc with 6 pin mini DIN DATA socket Modem Pin 1 radio Pin 1 Data in packet data input Modem Pin 2 GND radio Pin 2 Ground Modem Pin 3 radio Pin PTT standby Modem Pin 4 DEMOD radio Pin 4 Data out 9600 Baud packet output TEKK KS960 Tnet Mini 9 pin sub D plug socket at the transceiver Modem Pin 1 radio Pin 4 Transmit Data in Modem Pin 2 GND radio Pin 2 Ground Modem Pin 3 radio Pin 3 PTT Line Modem Pin 4 DEMOD radio Pin 5 Receive Data out Reduce data out voltage via a 1 3 voltage divider 22 kO in series 10 kO parallel to 0 5 volt Settings and adjustments of modem FSK9601 Jumpers FSK9601 Note the modem board is built in in the TNC3 or TNC31 bottom up component side down The following description shows the modem board with the component side down Jumper 1 is near the edge of the modem board the jumper 4 is located with 4 to 5 mm distance to the modulation amplitude trimmer The jumpers are closed by normal 2 5 mm jumper bridges Unused jumpers may be plugged parallel to the board edge on the pins which are nearest to the board All these pins are connected to ground WB jumper installed no jumper Normal mode The modem is shipped with no jumpers active The jumpers are plugged parallel to the board on the ground pins DIN Connector Trimmer 4 3 2 1 N
4. it should be reduced by a voltage divider which is mounted in the radio to get 0 7 Volt or less The input resistance of the modem is about 100 in parallel with the input filter capacitance 100 pF Input voltages exceeding 1 volt are limited by a diode pair causing excessive distortion of the signal Make sure not to over drive the input to avoid this PTT Pin 3 This pin is switched to ground when transmitting With this all common PTT circuits of the usual radios may be operated The switch in the TNC is a n channel vertical MOS field effect transistor VMOS FET which is able to switch up to 25 Volts and up to 250 mA In the on state the resistance of the FET is typically 30 or less the cut off current when switched off is far below 1 pA VMOS FETs are suited well for such applications because the voltage across the switched on FET is low only a few mV Bipolar silicon npn transistors have usually saturation voltages which are much higher FSK 9601 Page 4 With this circuit it is only possible to switch DC voltages up to about 20 Volts to ground You cannot pull a line up to 12 Volt when transmitting or switch a negative voltage For this application you should use a switching amplifier or a reed relay with diode clamp At most handy radios the PTT contact and microphone is connected to the same signal pin The AF path for the micro phone signal is decoupled by a series capacitor the PTT signal is fed by a series
5. from modem to TNC RXD and TXD can be encoded NRZ as well as NRZI 5 8 9 CTS transmitter is keyed from modemto 10 Signal description digital interface Reset Pin 5 modem input normally high is pulled low for 50 ms at power on of TNC3 not used in FSK9601 DCD Pin 7 Data Carrier Detect modem output High modem receives no carrier low modem has locked on a G3RUH signal CTS Pin 9 Clear to Send modem output Normally high If the modem is ready to transmit data the signal is low With the FSK9600 CTS output is connected to PTT input The TNC will wait for CTS low before data transmission starts PTT Pin 11 Push to talk or RTS Request to send modem input normally high When the transmitter is to be keyed the TNC pulls this signal to low TXD Pin 13 Transmit Data modem input The data is latched at rising edge low to high transition of transmit clock RXD Pin 15 Receive Data modem output The data output changes at the falling edge and is valid at the rising edge low to high transition of the receive clock TXC Pin 17 Transmit Clock modem output The modem generates a clock frequency which determines the transmit baudrate and the data speed between TNC and modem Transmit data signal TXD has to be stable at the rising edge of TXC FSK 9601 Page 3 RXC Pin 19 Receive Clock modem output the output of the receive clock recovery circuit is sent to the to sy
6. jumpers in modem FSK9601 Watchdog solder jumper 16 Jumper J17 RX muting Jumpers for selecting the baudrate Test pins on modem 9601 Setting the Baudrate with 9 Schematics Modem 96 1 Component Location Modem FSK9601 C Copyright for Hard and Preface This manual should help you to use the FSK Packet Radio Modem FSK9601 in your TNC3 or TNC31 controller and to install the connection to your radio transceiver If there are any problems you may ask for help vie a mail at support symek com With this manual the expression FSK9601 is used However all parts of the manual are valid for the various options of FSK9601 for baudrates from 4800 up to 614 kBaud as well If you need instructions how to modify a specific amateur radio transceiver for 9600 baud operation ask us We have a collec tion of many plans how to modify the transceivers Write us an e mail we shall reply and attach the information requested if possible Options for FSK9601 The FSK9601 board is tested and ready for use in the TNC3 or TNC31 For use with other packet radio controllers it may be necessary to use an additional 20 wire ribbon cable The data exchange
7. SK modem to a radio requires modification of the radio in most cases You have to find a suited point in the transmitter circuit to modulate the transmitter without significant distortion The receiver circuit has to be tapped directly after the demodulator to get an unfiltered signal For connecting the radio use a 5 pin DIN connector 180 degree pinning The five pins are numbered as shown view to solder side of plug view to front of the socket Pin 1 MODULATOR of radio output of modem Pin 2 GND ground Pin 3 PTT transmitter keying push to talk contact to ground Pin 4 DEMODULATOR output of radio input of modem Pin 5 N C Note the five pins are not enumerated in turn Modulator Pin 1 Here the modulator of the radio is connected The maximum output voltage of the modem is up to approx 3 5 B and could be adjusted with the only trimmer resistor accessible at the rear side of TNC3 31 The minimal output voltage which could be set is about 10 to 20 mV Below this the adjustment becomes somewhat fiddly The modem has a output amplifier with a series output resistance of 2 kO Sometimes the radio requires much less AF voltage e g only 10 mV for sufficient modulation For this case the AF voltage must be reduced by a voltage divider which should be placed in the radio The output of the modem should be about 1 Volt for good adjustment with the pot near middle position This gives less susceptibility to hum and nois
8. Users Manual for the Packet Radio Modem FSK 9601 Layout Version FSK9601 C 9600 19200 38400 76800 153600 Baud etc Issue 14 05 2005 12 52 00 Production and Distribution SYMEK GmbH Datentechnik Ulf Kumm DK9SJ Adress D 70597 Stuttgart Sonnenberg Johannes Kr mer StraBe 34 Phone 49 711 76 78 923 Fax 49 711 76 78 924 Hotline 49 711 76 54 911 eMail info symek com Internet http symek com Table of contents Table of contents s uH Dosen pA se Re Preface Options for FSK9601 Technical data FSK 9601 C Short description Bit rate and baudrate Digital interface 20 pin connector Signal description digital interface Connecting the FSK9601 to general TNC2 Connecting the radio to FSK9601 Modulator Pin 1 Demodulator Pin 4 PTT Pin 3 GND Pini 2 reines Standard FSK connection cable TRX4S Kenwood Yaesu Azden etc TEKK KS960 Tnet Mini Settings and adjustments of modem FSK9601 Jumpers 9601 Bit Error Test Jumper 1 Permanent transmit on PTT jumper 2 FSK GMSK switch jumper 3 Filter select switch jumper 4 Solder programmable
9. aud 9600 bit s optional other baudrates AF output level adjustable from 10 to 3 5 V p Rj 2kQ DC free up to 6 V DC permissible Output is muted while reception PTT max 25V 0 1A to ground input sensitivity 100 700 op at 100 DC free A input limiter 0 5V avoids overdriving the amplifiers by short DC peaks at T R switching FSK 9601 Page 2 NF filter 8 bit wide 512 tap FIR Filter in the transmitter with 64 fold oversampling DK9SJ type Active lowpass filters in TX and RX All inputs and outputs to the radio are filtered with R C R filters for EMI suppression A FSK filter raised cosine rolloff and a GMSK filter are selectable by a jumper Modem interface digital CMOS level 5 volt TXData TXClock RXData RXClock RTS CTS DCD 5 volt reset ground Connector 20 pin 2x10 ribbon connector LED display DCD carrier detect PTT transmitter keying Jumpers and trimmers 4 jumpers for PTT keying bit Error test FSK GMSK filter and spare filter select Setting of output voltage with a 20 turn trim mer Watchdog The PTT switch is time limited to approx 15 seconds In case of failure of the TNC the PTT is released after the maximum time For tests or special applications digipeaters with long transmission periods the watchdog may be disabled by a solder jumper Jumpers on board AF output muting on off baudrate 9600 19200 38400 76k8 153k 307k Baud watchdog disable Differe
10. between TNC3 31 and the modem is NRZI formatted If you want to use the FSK9601 with a TNC2 you need to order the option NRZ because here the data format is NRZ The difference between standard NRZI and optional NRZ version is only the programming of two of the three GALs They are marked R T and for the optional NRZ version The GALs cannot be changed so you have to order the modem with Option NRZ GAL Most power of FSK9601 is consumed by the GALs There are versions with zero power GALs available which reduce the total supply current of the modem from 115 to 30 mA at 5 volt The GALs cannot be changed so you have to order the mo dem with Option Zero power GAL Standard speed options for FSK9601 range from 9600 to 307200 Baud Receive and transmit baudrate may be different with one modem e g the combination receive 38400 and transmit 9600 is common for satellites with fast downlink data rates Receive baudrates from 2400 to 1228800 Baud and transmit baudrates from 9600 to 614400 Baud are possible Odd baudrates not a 2 multiple of 2400 Baud are available on special request Technical data FSK 9601 C Power supply 5 volt DC typ 125 mA Option low power 30 mA typical values Dimensions ca Length 120mm Width 41mm Height 25 mm mass approx 45 grams Radio interface 5 pin DIN connector same pinning as TNC2 TNC2S TNC2H etc Modulation filter scrambler according to specifications of GS3RUH speed 9600 b
11. e Another fine place for the voltage divider is the DIN plug The output voltage is coupled via an electrolytic capacitor There should be no DC voltage applied to pin 1 which is more positive then 2 5 Volt because the output capacitor of TNC will be reversed in polarity If the modulation input of your radio shows more voltage you should connect a 10uF capacitor in series minus connection directed to the modem The transmit signal sounds like white noise but on a oscilloscope you recognise pulses with a distance of about 0 1 ms at 9600 Baud IMPORTANT the correct adjustment of the transmit AF is very important As the radios are modulated directly there is no AF amplifier or modulation limiter you may far overdrive the modulator by applying too much AF voltage This gives the transmit signal an excessive bandwidth and the IF filter of the destination receiver will totally distort the signal We advice to watch closely the eye diagram at the receiver and adjust then the proper modulation level If the AF is too low you may loose some signal to noise ratio but you don t risk to distort the signal by overdriving Demodulator Pin 4 The demodulator output of the radio is connected to this pin The AF voltage should be 150 mV or more The decoder works at voltages of 50 mV or more without errors but the DCD LED will flicker and the modem is sensitive against signal distor tions If the output of your radio produces much more signal voltage
12. filter EPROM can store up to four different sets of filter coefficients Standard is FSK GMSK operation Two addi tional filter curves may be selected by installing jumper 4 With the standard modem this has no effect future use GMSK Filter enabled Filter select switch jumper 4 DIN Connector Trimmer 4 3 2 1 Optional filter enabled future use Solder programmable jumpers in modem FSK9601 For special applications there are some solder jumpers on the bottom side of the FSK9601 board To open soldered jumpers carefully remove the solder with desolderung wick J6 and J17 are closed by a copper trace which has to be cut with a small sharp knife 12 e e s s s e mmu B HEHE a BEB BRB EBB REPRE Fee eee a 232 mu e e e e s ll eM c A 0 0 28 0 Bottom side solder side of the printed circuit board FSK9601 C Watchdog solder jumper 16 The FSK9601 modem will key a transmitter only for a limited time If the watchdog timer approx 15 seconds is expired the PTT is released and the transceiver returns to receive mode even when the TNC keeps the PTT control line to So it can be made sure that the TNC does not key up the transmitter permanently even in case of a
13. nchro nise the received data signal RXD is stable at the rising edge of RXC The frequency of RXC corresponds to the transmit clock of the remote transmitter If the internal clock of the modem and the clock of the remote transmitter differ by some per cent the receive clock is adjusted by 1 32 clock cycle to maintain synchronism Connecting the FSK9601 to general TNC2 If the FSK9601 is to be used with a TNC2 the 6 signals are connected to the Z80 SIO as follows Pinning refers to 40 pin Z80 SIO SIO Ping Modem Pin 1 and 3 5 Volt SIO Pin 19 Modem Pin 7 DCD SIO Pin18 Modem Pin 9 CTS SIO Pin 17 Modem Pin 11 RTS SIO Pin 13 Modem Pin 13 TXD SIO Pin 12 Modem Pin 15 RXD SIO Pin 14 Modem Pin 17 SIO Pin13 Modem Pin 19 RXC SIO Pin31 Modem Pins 2 4 6 20 GND Note for 9600 baud operation the system clock of the TNC2 should be 10 MHz or higher The NRZ option GALs of the FSK9601 must be used As the G3RUH modem includes a scrambler it would make no difference in transmit spectrum if NRZ or NRZI is used How ever to keep all systems compatible the NRZ and NRZI versions have to be observed Using two modems with the wrong GALs would result in the same perfect communication however other modems with the correct NRZ NRZI setting cannot read this signals Connecting the radio to FSK9601 Connecting a 9600 baud F
14. nt TX and RX baudrates are selectable Short description A modem contains modulator and demodulator circuits The FSK9601 converts the digital signals of a packet radio controller to low frequent tones which can be transmitted by a FM radio Further it decodes the tones received by a FM radio and sends them to the packet radio controller in digital form The modem FSK9601 generates and receives AF signals according the G3RUH recommendations which is usual with ama teur radio on terrestrial and satellite links all frequencies are quartz controlled adjustments are not necessary The audio bandwidth of the signal goes from 30 Hz to 5000 Hz 9600 bit s With other baudrates the bandwidth is higher or lower ac cording to the speed The transmit clock frequency 9600 Hz is generated in the modem The modem includes also the circuitry for transmitter keying PTT and transmit time limiter watchdog Bit rate and baudrate In this manual the expressions bit rate bit s bit per second and baud Bd are used for determining the transmission speed With the FSK9601 both values are equivalent as there is exactly 1 bit transmitted with every clock cycle In general it is possible to transmit more than 1 bit per clock the speed in bit s is then a multiple of the clock rate Digital interface 20 pin connector power supply 5 volt 150 mA from TNC power supply 5 volt 150 mA from TNC not used in FSK9600 AF carrier detect
15. oise spectrum contains components which are recognised by the DCD circuit of the FSK9601 as valid data signal This cannot be avoided and may cause the DCD led to flash sometimes even if there is no data signal present If there is absolutely NO signal at the input short circuit no noise it may happen that the last state of the DCD remains ON until there is a new signal at the input The input signal should therefore be unsquelched otherwise the transmitter could be blocked due to an apparent busy channel Countermeasures A 1 MOhm resistor could be soldered parallel to R35 FSK 9601 Page 7 Schematics Modem FSK9601 C I a Be c3 i FSK 9601 Page 8 Component Location Modem FSK9601 C ee n e e a n a is m BH HB m ge e a EN E m e a ol EESTI a a e a a B E a E g E Bn gt E m 60000 2 2m a a e e B eels E a a sa g m 000060 H B oe e 00 00 E 00000 E B wee m
16. ormal mode FSK Bit Error Test Jumper 1 To run the bit error test BERT the transmitter is set to permanent zero transmission Check at the remote receiver for ones Every pair of ones represents a transmission error BERT is useful for test and adjustment of the signal path NOTE if jumper 1 os closed no ndata can be transmitted However the TNC may key up the transmitter and apparently data is sent But with BERT jumper installed this data contains no information and no connect is possible DIN Connector Trimmer 4 3 2 1 With jumper 2 the PTT of the radio may be keyed This is used for tests and adjustment The transmit time limiter Watchdog is not in effect when keying the PTT by jumper 2 For normal operation set jumper 2 always OFF Bit Error Test mode enabled Permanent transmit on PTT jumper 2 For testing it makes sense to install jumper 1 BERT and jumper 2 transmit at the same time FSK 9601 Page 5 As long as transmitter is keyed by command or by jumper 2 the modem transmitter is NOT muted DIN Connector Trimmer 4 3 2 1 With jumper 3 the transmit characteristic can be switched from the usual FSK modulation to GMSK Both modulation types are alike if there is not much noise present you will find no difference For best results use the FSK filter jumper not in stalled permanent transmit ON FSK GMSK switch jumper 3 DIN Connector Trimmer 4 3 2 1 The
17. resistor of 2 to 20 kO in order not to short circuit the microphone When pressing the PTT switch DC current may flow through this resistor keying the transmitter As the microphone will not be used with the 9600 Baud FSK modem the mic connector of the radio may be connected directly to the PTT pin of the modem Then the short circuit of the mic modulation is no disadvantage GND Pin 2 Ground of the radio case 0 Volt Standard FSK connection cable for transceivers with 9600 Baud FSK Capability Since about 1994 the industry begun to produce amateur radio transceivers with the necessary inputs and outputs for 9600 Baud FSK The transceivers of Kenwood Azden Alinco Yaesu ICOM SYMEK use the same connector and pinning and are easy to connect to a FSK9600 The radios have a 6 pin mini DIN socket same type as for PS 2 keyboards You have to make a simple cable with a 6 pin jack on the one side and the 5 pin DIN jack on the other Just connect the pins 1 to 1 2 to 2 3 to 3 and 4 to 4 Pins 5 and 6 remain unconnected As it is difficult to solder the tiny 6 pin jack it is better to buy a ready made PS 2 keyboard extension cable cut it into two pieces and attach the 5 pin DIN connector to the open end Read the manual of the radio how the FSK mode is to be enabled and how to adjust sensitivity If the demodulator output voltage exceeds 0 5 volt it is a good idea to reduce it to that level by soldering a voltage divider into the cable plug
18. software malfunction This circuit is called Watchdog For full duplex or digipeater use this watchdog function may be disabled by soldering jumper J16 This may be also useful for some tests if the transmitter is to be keyed up for longer periods With jumper 2 see above the transmitter may be keyed up independantly from the watchdog setting Jumper 917 RX muting In receive mode the transmitter modulation output of the modem is muted Jumper MUTE installed If a signal has to be generated even in receive mode the trace J17 has to be removed FSK 9601 Page 6 Jumpers for selecting baudrate For setting the transmit or receive baudrate you have to change not only the jumpers but some components of the analog filters too However we explain the function of the related solder jumpers here TXBaud 9600 19200 38400 76800 153600 307200 3072004 614400 RX 2400 J2 J6 RX 4800 J3 J6 J2 J8 RX 9600 J4 J6 J3 J8 J2 J10 RX 19200 J5 J6 J8 J8 910 J2 12 RX 38400 99 J6 J5 98 J10 93 914 192 714 2 12 76800 11 06 711 98 195 10 4012 3 7314 J2 J14 3 14 2 14 153k 13 96 1913 8 J134 J10 5 912 44 914 14 4 12 03 14 307k 15 96 715 8 115 10 15 J12 95 14 14 5 12 J4 J14 RX 614k J15 J6 1915 98 J15 J10 J15 J10 J5 J14 614 1
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