| 摘要 |
The invention discloses radio frequency zero crossing signal generators for optical disc drives, comprising a controllable low pass filter, a comparator, and a control circuit. The controllable low pass filter evaluates an average level of the magnitude of a radio frequency ripple from an optical disc drive. The comparator compares the radio frequency ripple to the average level evaluated by the controllable low pass filter to generate a radio frequency zero crossing signal. When the optical disc drive reads a fingerprint defect on an optical disc, the control circuit adjusts a cut-off frequency of the controllable low pass filter to adjust the speed at which the controllable low pass filter evaluates the average level.
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