| 摘要 |
PROBLEM TO BE SOLVED: To increase a lowered gain under automatic gain control even when the gains of a gain control amplifier is temporarily lowered concerning an automatic gain control circuit with which an input video signal is amplified by the gain control amplifier and converted into a digital signal by an A/D converter, a difference is outputted from an error detecting part when an output signal exceeds a peak level setting value, '0' is outputted when the output signal does not exceed the set value, the output is integrated by an integrator and the integrated value is converted into an analog signal by a D/A converter and outputted to the gain control amplifier. SOLUTION: An integrator 18a is provided with an internal register 24 for replacing an integrated value, and a read/write control means (microcomputer) 22 is provided for reading the replaced value of the internal register 24 at the interval of fixed time, adding a preset fixed value K to the read integrated value when s matching state is continued for set time and writing the result into the internal register 24 as a new integrated value.
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