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MR1200

RADIO MODEM 1200 bauds

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USER MANUAL

908709-02

(AUGUST 2000)

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Summary of Contents for MR1200

Page 1: ...MR1200 RADIO MODEM 1200 bauds USER MANUAL 908709 02 AUGUST 2000 ...

Page 2: ......

Page 3: ...tion push to talk 16 2 8 3 Microphone connection 17 2 9 T R POWER SUPPLY 17 3 CONFIGURATION 19 3 1 ENTERING CONFIGURATION MODE 19 3 2 CONFIGURATION COMMANDS 19 3 3 QUICK CONFIGURATION 20 3 4 OPERATING PARAMETERS AND OPTIONS 21 3 4 1 Configuring the terminal modem interface 21 3 4 2 Configuring the radio interface 23 3 4 3 Operating parameter 25 3 4 4 Power saving feature 26 3 4 5 Other parameters ...

Page 4: ...rogramming 36 4 4 3 Radio relay control 37 4 4 4 Usage in a V25bis call command 37 4 5 POWER SUPPLY SAVING SLEEP MODE 38 4 5 1 Operation 38 4 5 2 Sleep model 38 4 5 3 Transceiver wake up 38 4 5 4 Power state up 39 4 5 5 Configuration mode wake up 39 4 6 SPEECH USE 39 ...

Page 5: ...nchronous data transmission using FFSK modulation at 1200 b s or 2400 b s plus data protection using an error correction code RS232 or RS485 serial link to the Data Terminal Equipment with a choice of command modes including 3 wire automatic mode TxD RxD ground in RS232 mode 15 way sub D connector for connection to the external transceiver Radio channel access conflict management multiple equipmen...

Page 6: ...L 908709 02 Minimal power consumption of 50 mA reduced to 300 µA using the power saving feature Durable and compact case housing the data handling interface card Completely configurable from an ASCII terminal using an elementary set of commands ...

Page 7: ...tion therefore it will be necessary to site the modem transceiver Data Terminal Equipment battery and any temperature regulating devices in a clean dry enclosure 2 2 External description The MR1200 modem is housed in a metal box Dimensions 180 x 130 x 45 L x W x H Overall weight 550 g Impact and penetration IP40 Fixing centres 150 mm 120 mm ...

Page 8: ... The different circuits carried on the interface are shown in the following table Pin Circuit Function Usage according to control mode automatic direct V25bis 1 109 DCD Detection of modulated carrier optional optional optional 2 104 RxD Data reception yes yes yes 3 103 TxD Data transmission yes yes yes 4 108 2 DTR Wake up V25bis dialogue optional optional yes 5 102 SG Signal ground yes yes yes 6 1...

Page 9: ...on an isolated site a 12V lead battery is an ideal solution The MR1200 is fitted with a circular male power supply connector whose pinout is as shown 1 12 V 2 ground 3 not connected Remarks The MR1200 does not possess an ON OFF switch The MR1200 works from a single source of power Where two power sources are used battery solar panels for example switching between them must be done externally 2 6 C...

Page 10: ...d 4 reserved 2 6 1 1 The LFout connection The output stage levels are calculated to match the VCO input of a classic analogue phase modulated transmitter The circuit diagram below shows an amplification stage IC3 A R25 P3 with gain adjustment using the multiturn potentiometer P3 a signal pre emphasis stage IC3 B C17 C15 C3 C4 R19 R11 R12 providing the correct levels at the VCO input to obtain the ...

Page 11: ...cy response spectrum will be required in order to determine the characteristics of any compensating filter needed to obtain the recommended radio channel frequency excursions The discreet components around IC3 B may be changed to achieve the correct filter response This is a delicate operation requiring radio frequency measuring equipment and an SMD soldering kit see ETIC 2 6 1 2 The LFin connecti...

Page 12: ... s when a signal of 1500 Hz 85 mV r m s is applied to the LFin input 2 6 1 3 The ALT connection The T R s change over to transmit mode ALTERNAT command either happens the instant circuit 105 RTS is set ON or when the ALT command generated by the data card is asserted A monostable triggered by 105 RTS prevents T R changeover occurring before data transmission has terminated RTS DATA ALTERNAT Soft D...

Page 13: ...logic signal the modem compares the DP signal from the transceiver with a threshold voltage IC1 R7 R20 R22 P2 C6 The threshold level is adjusted with P2 Using straps S3 and S4 a positive logic level can be generated whatever the nature of the DP signal input L5V S4 DP Logic S3 L5V S4 DP Logic S3 Straps S3 and S4 are factory set for a positive DP signal In the opposite case straps S3 and S4 need to...

Page 14: ...dulation at 2400 b s For FFSK modulation at 2400 b s the sub carriers coding bits 1 and 0 are respectively F1 1200 Hz and F0 2400 Hz Now 2400 b s is at the limit of the transmission chain bandwidth and any mismatching tolerable at 1200 b s will now produce signal alterations too severe for the modem to handle Furthermore in order to maintain the bit rate modulation frequency shifts at crossover ta...

Page 15: ...eep T R not powered In this case power for the T R is supplied through a relay controlled by the MR1200 Relay operation is described in chapter 4 5 3 Wake up initiated by 108 DTR or by the configuration mode push button being activated Configuring the straps for SLEEP MODE 1 Cut the copper track linking the pins of S12 component side and solder a strap in position as indicated on the drawing below...

Page 16: ...ication i e has a high impedance input better audio quality can be obtained by taking the LS signal directly from the output of IC3 D behind C8 and if necessary increasing the level by modifying the values of R3 and R17 consult ETIC The pinout of the female 9 way sub D connector is as shown 1 5 5 V cut when the MR1200 is in sleep mode 2 LS output 3 microphone input 4 transmit control o p PTT conne...

Page 17: ...ction The external microphone signal is amplified and filtered low pass filter IC3 A C18 R21 P3 C16 If necessary the signal level can altered by modifying resistor R21 consult ETIC 2 9 T R power supply The transceiver connected to the MR1200 should have an external power source For sleep mode operation the VREG output can then be used to control a T R power supply relay MR1200 TRANSCEIVER RX TX GN...

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Page 19: ... terminal has been installed and the equipment powered the operator pushes the CONFIGURATION miniature push button found on the modem front panel At this point any radio communication in progress will be terminated indicators TR and DP will come on and the following message will appear on the terminal screen C 2 1 1 Serial connector for terminal link male 9 way sub D 2 Miniature push button switch...

Page 20: ...s all the commands it receives on the terminal screen It is always possible to cancel this echo if the terminal echoes its keyboard input locally 3 3 Quick configuration This paragraph describes the minimum configuration necessary to get the modem up and running quickly When completed the MR1200 will function in automatic mode communication using 4 serial interface circuits 103 TD 104 RD 106 CTS a...

Page 21: ...he CONFIGURATION push button one last time will turn off the indicators and disconnect the terminal Connect the modem to one of the DTEs that will be using radio communication The MR1200 will work with a 4 wire cable carrying the RS232 serial interface circuits 103 TD 104 RD and 02 SG A wire for the 106 CTS signal is optional the modem uses this circuit for handshaking Check which DTE serial inter...

Page 22: ... simple automatic 2 direct 3 V25bis Either of the automatic modes is adequate in most instances having been designed to allow the modem to operate transparently using only circuits 103 TD and 104 RD and 106 CTS for handshaking if required In direct mode the terminal uses an extra circuit 105 RTS to control access to the radio channel before sending data The V25bis control mode uses all the serial ...

Page 23: ...is parameter set to 1 the RS232 interface 107 DSR circuit is implemented as per a standard telephone line modem 107 DSR is ON during communication radio channel and OFF when at rest Setting its value to 0 forces 107 DSR to the permanently ON condition ges_dsr 107 DSR handling 0 no permanently ON 1 yes ON in communication 3 4 2 Configuring the radio interface Parameter 020 mod_rad Defines the MR120...

Page 24: ...data is controlled by a master station master slaves network this option may be deselected to reduce modem turn around delay to a minimum Parameter 023 st_num Allows selection of the MR1200 CCIR ZVEI tone encoder operating mode st_num standard 0 CCIR 1 CCIR short 2 ZVEI 1 3 ZVEI 2 Parameter 024 seq_num Defines the tones to be emitted and or the protocol used by the MR1200 each time it goes into tr...

Page 25: ...receive data by being allocated a unique address notably when the V25bis control mode is used see chapter 4 The ad_mod parameter represents the individual modem s address ad_mod format from 0 to 255 BCD 0 no address If 0 is entered for this parameter the MR1200 will not use an address when it transmits data To address data to stations within a transmission network enter different non zero addresse...

Page 26: ...es 3 72 bytes 4 96 bytes 5 120 bytes 6 144 bytes 7 168 bytes 8 192 bytes 9 216 bytes 10 240 bytes Select a small packet size 48 bytes or less if transmission conditions are only mediocre Select a larger size 144 bytes or more if the radio link is of good quality and the data rate needs to be high Parameter 035 f_mem Alters the MR1200 s transmit data buffer size from 32 bytes to 2 Kbytes depending ...

Page 27: ...0 removes all limits on the duration of transmission Parameter 051 tp_sil A minimum period of post transmission silence can be defined to allow other MR1200 modems the time to access to the radio channel tp_sil units de 1 to 255 x 1 s 0 6 20 x duration of transmission The MR1200 ignores this parameter if no transmission time limit has been set parameter tp_emi null Parameter 052 tp_ae Corresponds ...

Page 28: ...he current communication in the absence of either data being sent or received tp_rc units de 0 to 999 x 50 ms 2 100 ms Enter a low value 100 ms where applications function by a rapid exchange of data with brief request response intervals in automatic or direct control mode Enter a higher value 1 s or more in V25bis control mode 3 5 Leaving configuration mode Once modem configuration has been compl...

Page 29: ...res strictly to the specifications laid down in the French standard ST PAA DIR 1382 Radio channel data transmission is synchronous and uses a data rate of 1200 or 2400 b s The modulation employed is of an indirect type an FFSK modulated audio frequency sub carrier phase modulates a radio frequency carrier Normal transmission is in base mode data to be transmitted is formatted into frames protected...

Page 30: ...ze will force the communicating modems to re synchronise the frequency depending on the application and the quality of the radio link f_paq parameter Half duplex transmission The MR1200 control of T R switching half duplex is transparent to the terminal The use of buffers enables terminal modem dialogue to remain duplex throughout The modem will switch from transmission to reception according to a...

Page 31: ...sen Circuit Name Pin Direction Function Control mode implementation automatic direct V25bis 102 SG 5 Signal ground yes yes yes 103 TD 3 terminal modem Transmitted data yes yes yes 104 RD 2 modem terminal Received data yes yes yes 105 RTS 7 terminal modem Ready to send yes 106 CTS 8 modem terminal Clear to send advised yes yes 107 DSR 6 modem terminal Data set ready optional advised yes 108 2 DTR 4...

Page 32: ...ition set during the period of radio data transfer and an OFF condition set when communication has ended However the configuration option exists to set this circuit permanently ON ges_dsr parameter Circuit 106 CTS is ON most of the time being set OFF only when the data transmission buffer overflows The signal may be used to control data flow from the terminal 4 3 3 Marked automatic mode Marked aut...

Page 33: ... and set OFF when communication ends It can however be configured to be ON permanently ges_dsr parameter Once radio transmission has begun 107 CTS remains ON and is only set OFF to signal transmission data buffer overflow The signal can be used to control data flow from the terminal 4 3 5 V25bis mode The V25bis control mode makes a more extensive use of the serial interface only 105 RTS is unused ...

Page 34: ...e transmit command ss s call sequence CNX Transmission of sequence terminated Modem at rest INC Detection of a radio transmission addressed to the modem RES0 Reinitialise terminal modem dialogue VAL Reinitialisation carried out RES1 Reinitialise modem with default parameters VAL Reinitialisation carried out Remarks The symbols p or a represent ASCII numbers The value vv v of a parameter is given i...

Page 35: ...ncoming data when in the rest state it simultaneously sets ON 125 RI and 109 CD The terminal then has 6 seconds to accept the call by setting ON 108 2 DTR otherwise any incoming data will be lost If the terminal sets ON 108 2 DTR or if data communication is detected when a dialogue is in progress the MR1200 sets OFF 125 RI and sends an incoming call message to the terminal INC 106 CTS is then set ...

Page 36: ...between CCIR or ZVEI mode is programmable st_num parameter The tones to transmit and or the radio channel access code are defined in a call sequence comprising a chain of up to 10 max ASCII characters chosen from the following symbols 0 to 9 A to E transmit corresponding tone CCIR or ZVEI mode test for channel availability no radio carrier wait time 6s max test relay carrier activation follows seq...

Page 37: ...l the MR1200 using its carrier detect facility to check channel availability each time before it transmits similar to a sequence To activate and control a CCIR or ZVEI relay carrier the seq_num parameter must be programmed with a sequence respecting the following syntax nn n where nn n is the selective call number of the relay CCIR or ZVEI mode is selected by the st_num parameter value 4 4 4 Usage...

Page 38: ...upply operation of the configuration button Note the sleep mode chosen is set by straps on the circuit board 4 5 2 Sleep mode When inactive the MR1200 drops into sleep mode after a configurable time delay of between 1 second and 60 minutes att_ina parameter If one of the above events occurs before the time out the modem remains awake and the countdown is stopped Note The att_ina parameter can be f...

Page 39: ...en place 4 6 Speech use Where applications use the radio channel for both speech and data communication the MR1200 can be equipped with a microphone loudspeaker set In this case the phonie option must be selected When the operator wishes to speak he pushes the transmit receive button on the set The MR1200 then suspends all current data communication and switches the T R into transmission Holding t...

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