Sampled amplitude read channel employing a remod/demod sequence detector

Abstract

A sampled amplitude read channel is disclosed for disk storage systems that employs a remod/demod sequence detector guided by an error syndrome of an error detection code (EDC). The remod/demod sequence detector comprises: a conventional trellis type maximum likelihood sequence detector, such as a Viterbi detector, for detecting a preliminary binary sequence from the channel sample values; a syndrome generator for generating an error syndrome in response to the preliminary binary sequence; a remodulator for remodulating the detected binary sequence into a sequence of estimated ideal sample values; a sample error generator for subtracting the channel samples from the estimated samples to generate a sample error sequence; an error pattern detector for detecting potential error events in the sample error sequence; and an error corrector for correcting the preliminary binary sequence when the error syndrome indicates that an error occurred. In the embodiment disclosed herein, the error syndrome is generated as the parity over a predetermined number of bits. When a parity error occurs, a correction is made corresponding to the most likely error event detected. Guiding the remod/demod sequence detector with an error syndrome avoids miscorrections that may otherwise occur in conventional remod/demod sequence detectors.