| 摘要 |
PURPOSE:To suppress the noise caused in the no-signal time in any state with simple constitution and in a quick and accurate way, by always transmitting the false signal at the outside of an intermediate frequency band to an intermediate frequency amplifier to control an amplitude limiter. CONSTITUTION:The false signal at the outside of an intermediate frequency band which is transmitted from an intermediate frequency band signal generator 9 is transmitted at all times to an intermediate frequency amplifier 2 via an attenuator 8. When a desired intermediate frequency signal is not supplied, the gain of an amplitude limiter is controlled by the false signal to transmit no noise in the no-signal time. When a desired intermediate frequency signal is supplied, the desired signal that is selected and amplified through an intermediate frequency band pass filter 1 and the amplifier 2 is supplied to the limiter 3 along with the above-mentioned false signal. Then the modulated signal of a desired wave is delivered thruogh a frequency discriminator 4 when the level of the desired intermediate frequency signal exceeds the level of the false signal. |
