| 摘要 |
<p>An optical disk device comprises a variable gain amplifier (203: VGA) for amplifying the amplitude of the signal picked up by a pickup (202), an A/D converter (204) for digitizing the amplified signal, and an amplitude detecting circuit (206) for detecting the amplitude information from the digitized information. The optical disk device further comprises a gain control circuit (205) for computing the control value of the VGA (203) from the detected amplitude information and an envelop generating circuit (207) for conducting computation for absorbing the transfer characteristic of the VGA (203) from the control value of the VGA (203) and the amplitude information so as to generate the envelop picked up by the pickup (202). When the characteristic of the VGA (203) varies, the degree of the variation is computed from the amplitude information on the signal picked up by the pickup (202) and the amplitude information acquired by fixing the control value of the VGA (203) to correct the characteristic.</p> |
