| 摘要 |
PURPOSE:To exerise smooth automatic gain control without being affected by the presence or absence of a modulation signal, by extracting a signal proportional to the amplitude of a carrier signal for exercising automatic gain control. CONSTITUTION:An output of a synchronous detector 7 is applied to a low pass filter 10 for DC component extraction. The filter 10 can extract a low frequency component from a DC to 50-100Hz, extracts the DC component proportional to the amplitude of the carrier signal, and the automatic gain control is exercisid by feeding back the DC component to a high frequency amplifier 1, an intermediate frequency amplifier 4 or a mixer 3. As a result, the control is exercised in response to the carrier signal amplitude without being affected by the modulation signal. |
