DSP Implementation of OQPSK Baseband Demodulator for Geosynchronous Multichannel TDMA Satellite Receiver

Abstract

Geosynchronous satellite and development of its earth-based receiver has a lot of importance in satellite networks. The geosynchronous time division multiple access (TDMA) narrowband satellite receiver must have the ability to do proper baseband processing including frequency and time synchronization, phase offset correction, and baseband demodulation. This paper discusses the efficient implementation of baseband processing implemented in Texas Instruments (TI) multicore TMS320C6678 DSP for a field-deployable geosynchronous multichannel TDMA satellite receiver. It also discusses a complete discrete domain baseband processing technique for demodulating OQPSK-modulated bursts for a geosynchronous satellite receiver. In the proposed implementation, high multichannel capacity is easily attainable because of the reduced computational time and reduced complexity. Bit error rate (BER) performance exhibited in this implementation matches the requirements for a satellite receiver. The technique proposed in this paper is rather enticing due to the narrowed estimation error limit which is attainable with even a short preamble, especially for OQPSK-modulated bursts with its self-induced inter-symbol interference (ISI).