Improving performance of PRML/EPRML through noise prediction

Sequence estimation detectors for the digital magnetic recording channel based on noise-predictive partial-response equalization are described. Called noise-predictive maximum-likelihood (NPML) detectors, they imbed a noise prediction/whitening process into the branch metric computation of a Viterbi detector. Simulation results show that a judicious tradeoff between system parameters leads to substantial performance gains over both PRML and EPRML systems. A programmable 8-state NPML detector without decision feedback is presented.