| 摘要 |
SSB receivers which use feedback and feedforward automatic gain control (AGC) are subject to bursts of noise in the audio output due to the action of the feedforward AGC when signals having low signal to noise (S/N) ratios are being received. This invention minimizes such noise bursts by disabling the feedforward AGC at a predetermined threshold S/N ratio independent of the feedback AGC control voltage. Noise within the received channel is bandpass filtered and a first signal generated which has an amplitude proportional to the filtered noise. The first signal is compared with a reference voltage which corresponds to the threshold at which the feedforward AGC is disabled.
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