Abstract :
Describes the performance of a 4800 bit/s serial, voiceband HF radio modem that uses trellis coded modulation at the transmitter and near maximum likelihood decoding at the receiver, and compares this performance with that of the equivalent uncoded QPSK system. Both systems are tested under conditions of deep selective Rayleigh fading that is introduced by HF radio channel models with frequency spreads and multipath delays of upto 2 Hz and 3 ms, respectively. The testing is done via computer simulation and it is concluded that, for the particular system under test, the preferred scheme is uncoded QPSK modulation
