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3.7
Signalling Module MDSR 134
The MD 134 contains the function groups:
1.
Analog signalling
2.
Digital signalling (FFSK 1200 Baud)
3.
Clock conditioning
4.
Chip-Select logic for the unit control.
The MDSR 134 has been derived from a fusion of the components SR 130 and MD 134.
Analog Signalling (Function Scope of the SR 130)
The SR 130 is a universal encoder/decoder for analog tone signalling methods according to
ZVEI, CTCSS, CCIR, EIA standards. The SR 130 can be programmed for frequencies of 1 Hz to
4000 Hz.
Two separate tone signal generators allow use as a DTMF encoder.
Digital Signalling (Function Scope of the MD 134)
The MD 134 is an intelligent semiduplex modem. It processes a 1200-b/s FFSK signal. The two
frequencies are 1200 Hz for a logic 1 and 1800 Hz for a logic 0. The frame synchronisation is
achieved by comparison with a synchronisation word, in addition the inverse synchronisation word
is searched for. The synchronisation word is 32-bit freely programmable.
The module is controlled by the processor through a parallel interface.
Digital Signalling (Function Scope of the OKI modem)
A bit-transparent modem is used for RX decoding of the 1200 baud signalling.
A software control effects an automatic changeover from MDSR 134 to the OKI modem.
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