Digital signal reproducing apparatus using a viterbi decoder

摘要

A digital signal reproducing apparatus which can reproduce a digital signal without deteriorating the performance of a Viterbi decoder being deteriorated even if a positional error due to some mechanism causes in reproducing information from a recording medium or amplitude fluctuation in a red signal due to fluctuation in characteristics of the recording medium should occur. The digital signal reproducing apparatus performs an A/D conversion of a read signal read from the recording medium to convert it to a digital sample value series, obtains an amplitude value according to a result of subtraction between a maximum sample value having a maximum level of sample values in the sample value series and a minimum sample value having a minimum level of sample values in said sample value series, and supplies a value obtained by uniformly each of the estimated sample values in a Viterbi decoder by this amplitude value as a final estimated sample value to the Viterbi decoder.