Low bit-rate satellite demodulator implementation

In this paper we present the system design for a BPSK demodulator suitable for earth station implementation for satellite communications. The primary design goal has been to obtain a demodulator that has fast acquisition in a low signal-to-noise ratio environment. To this end the implementation uses structures and algorithms that are entirely feedforward. The system design has been analysed and verified by the use of software simulation and an implementation suitable for Inmarsat-C applications bas been developed using a Motorola DSP56001 target system. The key requirement was for a demodulator implementation that would operate both in a burst-mode and a continuous mode according to the signal types and specifications applicable for Inmarsat-C 'coast earth stations' and 'network control stations'. The design has resulted in a flexible implementation that could be easily adapted for many applications.