EQUALIZATION AND DETECTION IN STORAGE CHANNELS

In this work, a model for digital magnetic recording on thin-film medi a is developed, and the performances of several detector/run-length-li mited code combinations are compared under different densities, media noise, offtrack interference, and channel mismatch conditions. The stu dy is based on computer simulations using an experimentally extracted transition response of a magnetoresistive read head. The detection alg orithms considered include the partial response maximum likelihood det ectors, decision feedback equalizer (DFE), and fixed-delay tree search with decision feedback (FDTS/DF) detector. It was found that the DFE with a (0, k) run-length-limited (RLL) code and the FDTS/DF with a (1, 7) RLL code show the least bit error rate degradation, as the user de nsity increases beyond 2.5 bits/PW50. The PRML and DFE suffer less fro m offtrack interference. The (0, fi) coded DFE and the (1,7) coded EPR ML and FDTS/DF channels are relatively robust under PW50 mismatch. At a user density of 2.5, FDTS/DF (1, 7) and DFE; (0, k) are found to yie ld the best bit error performance under varying intensities of white G aussian noise and media noise.