Viterbi detector for narrow-band digital FM with limiter-discriminator detection

Considers a Viterbi detector for narrowband digital FM with limiter-discriminator detection. It is shown that the bit-error-rate performance of a four-state Viterbi detector is better than that of a two bit (or four-level) decision feedback method for GMSK on an additive white Gaussian noise (AWGN) channel. The four-state Viterbi detector can be applied to duobinary FM, generalized TFM, or any other continuous-phase modulation (CPM). Evaluating the relative performance between various digital FM schemes by minimum squared Euclidean distance is also discussed. Simulated performance for MSK, duobinary FM and GMSK with a Viterbi detector is given.