Hybrid trellis-coded CPFSK signalling

A hybrid trellis-coded CPFSK signalling which employs a time-varying mapper is considered to improve the performance of CPFSK signalling. The best obtainable codes are sound for the rate 1/2 encoder combined with a 4-ary CPFSK modulator. It is numerically found that the hybrid trellis-coded CPFSK signals increase the minimum Euclidean distance of the conventional trellis-coded CPFSK signals.