A 16/18 trellis code for EPR4 magnetic recording channel

For magnetic recording channels with EPR4 signaling, a rate 16/18 (0,6) trellis code and a time-varying Viterbi detector for the code are proposed and examined. A method to construct the code that has a pseudo matched spectral null (MSN) at the Nyquist frequency is described. We show that the TC-EPR4ML detection with the proposed 16/18 (0,6) code can provide 1.5 dB and 1 dB gains compared to the conventional 16/17 EPR4ML and 16/18 TC-PR4ML detection respectively at a user bit density of 2.5.