Performance evaluation for FDTS/DF on MR nonlinear channels

We evaluated the performance of fixed-delay tree-search detector with decision feedback (FDTS/DF) when used for nonlinear magneto-resistive (MR) read head channels. The feedback section of the FDTS/DF was replaced by RAM lookup table for nonlinear equalization. The evaluation was based on a computer simulation in which the read-back signal from the MR head was modeled from a measured MR transfer characteristic function and actual real reproduced isolated pulses. Performance was compared to that of PRML channels. We also compared the sensitivity of the FDTS/DF and PRML channels to variations in the recording channel frequency response due to head-medium spacing fluctuation. The results show that the FDTS/DF channel has good resistance to MR nonlinear distortion and channel response variations, and is superior to the PRML channels in terms of realistic recording channel response.