Improved performance of coded digital FM

The performance of convolutionally encoded narrow-band digital FM with Viterbi decoding was considered in some detail by Simon (1983) for a noncoherent limiter/discriminator (L/D) with integrate and dump (I&D) bit detection. Employing a new threshold receiver which averages the output of the I&D detector with the output of a sample and hold (S&H) detector, a 3-dB improvement over Simon´s results for the bit error probability with FM clicks is shown to be achievable. At low error rates, the performance of this new receiver is, moreover, comparable to that obtained when the clicks are exactly removed by Simon´s hypothetical “genie”