Codes for combating non-linearity in partial response channels

A rate 2/5 (2, 7/6) constrained code is designed. This code finds applications in partial response recording channels suffering from non-linearity. A 12-state finite state transition diagram (FSTD) encoder of this code is derived via judiciously splitting and merging states during code design. The state-independent decoder of this code is designed, requiring one current codeword, one future codeword, and two preceding codewords to decode one current codeword. This code combines the constraints of both (2, 7) and (0, k/I) codes, and thus outperforms (2, 7) or (0, k/I) codes in certain applications. The power spectrum of this code is evaluated and analyzed.