Patent ID: 7219296

Claim:
An information reproducing apparatus for performing maximum-likelihood decoding, comprising: a detecting section which detects information recorded in the recording medium and which outputs a reproduction signal; an equalizing section which performs partial response equalization of the reproduction signal and which outputs an equalized signal; a correcting section which corrects the potential of the equalized signal in accordance with a correction amount determined on the basis of a plurality of reference levels used for the maximum-likelihood decoding, to produce a corrected equalizing signal; and a maximum-likelihood decoding section which performs maximum-likelihood decoding of the corrected equalizing signal by referencing the plurality of reference levels, and which outputs a decoded signal; wherein, the plurality of reference levels used for the maximum-likelihood decoding are represented by LV( 1 ), LV( 2 ), . . . , LV(n−1), and LV(n) in sequence from the lowest level, and a plurality of levels for peaks in a histogram of equalized signals and that correspond to the reference levels are represented by LP( 1 ), LP( 2 ), . . . , LP(n−1), and LP(n) in sequence from the peak level whose value is smallest, the correction amount is determined by the correcting section to generate a value satisfying one of: LP (1)= LV (1)−α (where α is a constant), and LP ( n )= LV ( n )+α, and wherein the constant α is the same as a value LVd equal to each of the intervals between the plurality of reference levels used for the maximum-likelihood decoding and, based on the correction amount, the correcting section corrects a corresponding equalized signal level.