| 摘要 |
PROBLEM TO BE SOLVED: To correct asymmetry of digital data read from a recording medium by using a histogram. SOLUTION: In a histogram formed by expressing appearance frequency of each output value of digital data as a function of the output value, a value to be a center of symmetry of distribution of corrected output values is calculated as a checkpoint value (S102, S103). One group includes output values of digital data larger than the checkpoint value. The other group includes output values of digital data smaller than the checkpoint value. Based on an output value in the group in which waveform distortion due to asymmetry is relatively smaller, the output value in the other group is corrected (S104). In addition, asymmetry correction using histogram is applied to Viterbi decoding. COPYRIGHT: (C)2011,JPO&INPIT |
