On Coded M-ary Frequency Shift Keying

We discuss the combination of permutation codes and M-ary frequency shift keying. We show that this combination has special properties that can be used in power-line communications: e.g. constant envelopes, and error correction capability for impulsiveand narrow band noise. We give a simple convolutional encoding and decoding scheme. The outputs of a binary convolutional codes are mapped onto code words of a permutation code in such a way that the Hamming Distance is preserved, or even increased in some special cases. The demodulator consists of a classical envelope detector followed by a “soft-decision” matrix indicating the order of envelope magnitudes. We also show how permutation codes can be used to allow for multiple users with controlled interference.