Algorithm studies of BS digital system demodulator LSI

摘要

The new demodulation algorithm design challenges imposed by the characteristic of BS digital system having composite modulated (8/Q/BPSK) signals in the transmission stream are reported. In brief, dynamically configurable multi-format carrier recovery loop is required in carrier recovery. Conventional Zero-Crossing algorithm using only sign of received signals needs to be modified for implementing timing recovery. In an attempt to achieve better performance on Viterbi soft-decoder, a new hybrid 8PSK de-mapping scheme is to be introduced. Simulations on SPW (Signal Processing Worksystem) showed that carrier recovery convergence up to ±300kHz frequency offset as well as 0.17dB improvement at BER =1.0E-3 at Viterbi decoder output can be achieved.