Nonlinear multi-h phase codes for full response and partial response CPFSK modulation

A novel trellis coding technique called nonlinear multi-h signaling is introduced with both full response and partial response CPFSK signals. In contrast to ordinary multi-h phase codes, where the modulation index is changed at the end of every symbol interval, nonlinear multi-h phase codes are constructed by changing the modulation index based on the previous symbols, and the current symbol interval. Minimum Euclidean distances and spectra of nonlinear multi-h codes for binary full response and partial response CPFSK signals are calculated at different phase states and various selected modulation index patterns. Comparisons have been made with ordinary multi-h full response and partial response CPFSK signals. It is concluded that nonlinear multi-h phase codes with both full response and partial response CPFSK signals achieve significantly higher distance than other multi-h formats reported in the literature