Double trellis-coded CPM - Communications, 1988. ICC 88. Digital Technology - Spanning the Universe. Conference Record. IEEE

The method of multiple trellis-coded modulation is applied to continuous phase modulation (CPM). Especially double trellis-coded quaternary CPM schemes using convolutional codes with an effective rate 2/4 are considered. Tables of optimum codes and minimum Euclidean distances are given for several frequency impulses and numbers of trellis branches per symbol interval, which have to be processed by a Viterbi-decoder. The results are clearly superior to single trellis-coded schemes with rate 1/2 codes. These improvements are accomplished by a proper selection of double channel symbols. Additionally this method offers improved receiver implementation properties. For a further reduction of complexity a modified decision feedback sequenceestimation is posed.