SIGNAL SPACE DETECTOR FOR CHANNELS UTILIZING A CODE HAVING TIME VARYING CONSTRAINTS

摘要

Data is detected from a disc (112) in a disc drive (110) and provided as a sampled read signal including data samples provided in a plurality of time intervals. A signal space detector (320) is configured to detect the data, wherein the data is encoded according to a code having a time varying maximum transition run constraint which varies between a first and a second constraint over a plurality of time intervals. The detector (320) is configured to receive an input sample including a first plurality of terms indicative of one of a plurality of possible data symbols. One of the plurality of possible data symbols is eliminated based on the first constraint when the input sample then being detected is constrained by the first constraint, to provide a second plurality of remaining possible data symbols. An estimated data value is determined which corresponds to the input sample then being detected, by determining which of the second plurality of remaining possible data symbols is within a predetermined range of the input symbol.