| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve stabilized learning of parameters for recording and evaluation of a recording quality even when it is difficult to evaluate the recording quality directly from a reproduced signal of recorded data because of restriction in signal transmission properties and high density in recorded information in an optical disk. Ž<P>SOLUTION: When a phase shift of the reproduced signal relative to a channel clock is to be evaluated, based on a difference between an output from a waveform equalization circuit to equalize an input reproduced signal to a predetermined target equalization characteristic and the target equalization characteristic, a group delay characteristic with respect to the frequency of the waveform equalization circuit is fixed. Hence, an equalized waveform as an output from the waveform equalization circuit can preserve phase shift information of the inputted reproduced signal to correctly detect the phase shift of the reproduced waveform using the equalized waveform. It is hence possible to achieve, with high precision, optimal value learning of various parameters for the recording, reproduction, and servo by use of the phase shift as an index. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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