A digital signal processing based modem receiver for the INMARSAT Standard C system

Discusses how the demodulator/decoder features extensive use of digital signal processing and uses three TMS 32020 for demodulation and uses a 68000 microprocessor for decoding. The key reception parameters of frequency error, timing error (in the case of burst mode), signal to noise ratio and packet error rate are displayed on the VDU screen which with the keyboard forms the main interface to the operator. The principal requirement of the demodulator/decoder is to be able to receive a 600 symbol sec or 1200 symbol/sec burst mode signal which is used principally for signalling in the Standard C system or a 600 symbol/sec or 1200 symbol/sec quasicontinuous signal used for the transmission of messages in the Standard C system. The signal processing is addressed in considerable detail