| 摘要 |
PURPOSE:Not to cause an excessive input in the post-amplifier even the status has been varied from non-input to availabe input, by delaying and controlling a signal by the pre-amplifier when the signal has been input. CONSTITUTION:In case of the status that a signal is not input, the post-circuit is disconnected by the switch SW, and only the pre-circuit is operated. When an input signal has been generated, the squelch circuit 6 is opened, and the switch SW is closed after a fixed period of time by the delay circuit 9. In this delay time the automatic gain control system AGC1 shows the effect and controls the amplifier 3 so that an output signal from the switch to the pre-circuit can be controlled. Accordingly, it is possible to suppress generation of a noise due to an excessive input which has been generated in its head part when the input signal has been generated. |
