| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that detection of dropout is impossible because the recording format of a DVD-RAM or the like has no continuity due to the address information part (ID part) in RF signals. SOLUTION: In the circuit to detect dropout in RF signals, the AGC circuit to control the low frequency component in the amplitude of RF signals to be constant is provided with a function of muting the ID part. The AGC output potential during muting is fixed, the discharge current in a fast or slow envelope detection circuit is increased in the ID part, and signals are gated while the width of the signal to be detected is increased than that of the muted signals. Thus, the obtained optical disk device shows high detection accuracy for dropout even for the above recording format.
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