Sequence estimation scheme using Viterbi algorithm for improving bit error rate of binary continuous phase FSK with limiter discriminator and integrate and dump filter detection

For a communication scheme using binary continuous phase FSK with limiter-discriminator and integrate and dump filter detection the improvement of bit error rate at the receiver side has been carried out through the bandwidth optimization of the IF filter or the decision feedback equalization using multilevel decision method. This channel is inherently the intersymbol interference channel due to the narrow band IF filter, so sequence estimation techniques using the Viterbi algorithm can also be used, although the channel is not purely additive white Gaussian. The authors examine the actual BER improvement of the sequence estimation scheme for a few IF filter types for static AWGN channels using computer simulation. Very large estimation gains are obtained for the modulation index h≲0.5