| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that an optimum recording compensation is difficult because the exact edge shifting amount cannot be obtained due to the change of value in a least square Euclidean distance in the case of a method to make an target value of a viterbi decode adaptive for the purpose of compensating such a property of asymmetry that an optical disk is upper/lower asymmetric. SOLUTION: By an adaptive equalizer 24, a PR property is imparted to a run length restrictive code reproduced from the optical disk to equalize a waveform, and a tentative discrimination signal showing a tentative discriminated result of the signal after waveform equalization is outputted in company with the outputting of the signal after waveform equalization. By a viterbi decoder 25, a plurality of new target values are adaptively calculated from the tentative discrimination signal and the signal after waveform equalization, and the viterbi decoding is performed to one target value selected in accordance with the tentative discrimination signal or to the signal after waveform equalization to output binary data and metric information. By using these procedure, the least square Euclidean distance based on an actual signal after equalization is computed by an arithmetic section 29. A DSAM and SAMDEV are calculated by arithmetic sections 28, 32. COPYRIGHT: (C)2006,JPO&NCIPI
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