DSP techniques for use in low bit rate satellite modems

Discrete and custom built circuits can be used for high bit rates, whereas digital signal processors such as the TI 320 family can be used for lower bit rates. As the calculating power of these processors increase, more useful bandwidth can be obtained. The limiting factor in the use of the DSP processor is the number of instructions per sample and hence another approach is the use of multiple processors to increase the bandwidth and flexibility of these systems. Other factors to be considered is the efficiency of the coding and the trade offs that can be obtained by trading speed for memory capacity. Once the DSP hardware system is designed the use of software allows techniques to be implemented digitally which can multi-task, giving rise to techniques not readily available to the analogue engineer