Performance of the receivers of trellis-coded data signals transmitted through HF channels

Shows the results of investigation by computer simulation of several receiver structures for trellis-coded signals transmitted through an HF radio channel. It is well known that application of Ungerboeck codes jointly with PSK or QAM modulation and the soft-decision Viterbi algorithm results in 2-6 dB asymptotic gain depending on the applied code. However, it is worth investigating the effective gain over uncoded systems when deep selective fades and ISI occur and signal-to-noise ratio is low or moderate, as in HF channels