Patent ID: 6771580
Filing Date: 2004-08-03
Classification: G11B

Abstract:
A data reproduction apparatus sampling at a given rate a reproduced signal complying with a partial response waveform, calculating branch metric values in accordance with the Viterbi decoding algorithm by employing expected values defined by the partial response waveform and each of sampled values, calculating path metric values based on the branch metric values, selecting paths corresponding to data state transition in accordance with a given rule based on comparison results of the path metric values, and reproducing data based on the selected paths, the reproduced signal being obtained from a recording medium, the data reproduction apparatus comprising:difference value calculation means for calculating a difference between compared ones of the path metric values in selecting a corresponding one of the paths; alternative path selection means for selecting a path different from the corresponding one of the paths, which are selected in accordance with the given rule, as an alternative path based on the difference between the compared ones of the path metric values calculated in said difference value calculation means; and reproduced data determination means for determining data to be reproduced based on the paths selected in accordance with the given rule and the alternative path selected in said alternative path selection means.