| 摘要 |
PROBLEM TO BE SOLVED: To improve the accuracy of wobble signal detection for disc discrimination and to reduce discrimination errors due to noise. SOLUTION: A wobble signal generator 26 creates a wobble signal from an electrical signal which includes been obtained from conversion by a pickup 3. A bandpass filter (BPF) 27 is set to change its central frequency to a wobble frequency f0 and fn different from the wobble frequency, and the filter extracts the respective frequency components from the wobble signal. An amplitude-measuring section 28 measures amplitude levels A0 and An of the extracted multiple signals. A disc discriminator 30 compares the multiple amplitude levels and if the amplitude A0 is greater than the amplitude An by at least a threshold level Ath, determines that a wobble is present in the disc. COPYRIGHT: (C)2009,JPO&INPIT
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