Performance of trellis encoded tamed frequency modulation

Combinations of convolutional codes and tamed frequency modulation (TFM) are optimized as one entity for rate 1/2 and decoder complexities of up to 256 states. It is concluded that the best codes found so far belong to a class of codes called matched codes, which have the property of minimizing the complexity of the optimal Viterbi decoder. Coding gains of up to 7.68 dB are reported. The reported codes are the best codes for use with TFM in a Gaussian noise channel and assuming Viterbi decoding. Some of these codes are found to be catastrophic, yet the coded TFM scheme is free of this problem. The codes obtained are found to be superior to those obtained with traditional optimization techniques.<>