| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem of a deterioration possibility of accuracy of an evaluation value in an evaluation index of a PRML system calculated by using a conventional fixed Euclid distance in adaptive viterbi having an internal reference level of viterbi decoding changed. Ž<P>SOLUTION: In adaptive viterbi decoding having an internal reference level of viterbi decoding changed according to a playback signal, a difference between the changed reference level and a fixed reference level is extracted and, for dispersion of a difference metric obtained by using the changed reference level, normalization is performed for every patterns where Euclid distances are equal. Thus, a playback signal index not deteriorated in accuracy with respect to the change of the reference level is calculated while an increase in circuit scale is suppressed. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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