| 摘要 |
PROBLEM TO BE SOLVED: To appropriately discriminate an FCM signal even when a peak level is fluctuated by the variance of a disk or the variance of property of an optical pickup. SOLUTION: Two control voltages different each other are applied on a VCA 36, and the FCM signal is amplified by the VCA 36 with a gain corresponding to the applied control voltage. The peak level of amplified each FCM signal is detected by a peak hold circuit 38. By a DSP 44, an optimum control voltage, with which an optimum peak level can be obtained is calculated on the basis of each control voltage applied to the VCA 36 and the peak level detected by the peak hold circuit 38. The FCM signal is amplified by the VCA 36 on the basis of the calculated optimum control voltage X1.
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