| 摘要 |
PURPOSE:To apply clamping at a response speed suitable for the property of a DC level fluctuation of an input signal by increasing the time constant of an LPF so as to slow down the response of the clamping in receiving a satellite broadcast. CONSTITUTION:The LPF 7 consists of a time constant circuit comprising a resistor and a capacitor, and the time constant of the LPF 7 is changed by controlling whether or not a capacitor C2 is connected in parallel with a capacitor C1 by a switch 10. In case the input signal passes through a dispersal elimination and de-emphasis circuit 3, the switch 10 is closed to slow down the time constant of clamp response. In case the input signal does not pass through the said circuit 3, the switch 10 is opened to quicken the time constant of clamp response thereby obtaining a suitable clamp response speed in response to the input signal.
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