Patent ID: 6246723
Filing Date: 2001-06-12
Classification: G11B,H03M,H04L

Abstract:
A sampled amplitude read channel for reading data recorded on a disc storage medium by detecting an estimated sequence from discrete-time sample values generated by sampling pulses in an analog read signal from a read head positioned over the disc storage medium, comprising:(a) a sampling device for sampling the analog read signal to generate the discrete-time sample values;(b) a discrete-time trellis sequence detector operating according to a state transition diagram comprising a plurality of states, for detecting the estimated sequence from the discrete time sample values, the sequence detector comprising:(i) a metric generator for generating at least one accumulated error metric for each state in the state transition diagram relative to the discrete time sample value and a target sample value;(ii) at least one path memory corresponding to a path of a trellis diagram, wherein:the path memory stores a survivor sequence; and the path memory comprises a first memory element, a last memory element, and a plurality of intermediate memory elements;(iii) a metrics comparator for comparing at least two accumulated error metrics and fewer than all the states in the state transition diagram generated in response to the metric generator and outputting a compare signal and(iv) an early-decision output for outputting an early-decision estimated value generated in response to an intermediate memory element of the path memory.