| 摘要 |
PURPOSE:To output the output signal of a constant level at the modulation of an input signal, even at nonmodulation thereof by synthesizing an output of a variable attenuator attenuating an input signal and a signal being the result of phase delay of the output by pi and correcting the control voltage of an AGC circuit by the detected voltage of the synthesized signal. CONSTITUTION:A correction voltage generating circuit consisting of a 1st circuit 5 to a 4th circuit 8 detects the presence of modulation of an output signal IF OUT of a transmission quantity variable means 2 to generate a detection voltage Eadd. The detection voltage Eadd is inputted to an amplifier section 9 together with the detection output E of the detector 4 to control its output voltage (c). The detection voltage Eadd corrects the difference E of the detector 4 when a signal IFOUT is modulated signal and a nonmodulation signal and outputs the output voltage (c) of the amplifier section 9 at a constant value. When the output voltage (c) of the amplifier section 9 is constant, since the control voltage of the means 2 is constant, the transmission quantity given to an input signal IFIN by the transmission quantity variable means 2 is constant and its output signal IF OUT is kept constant. Thus, the transmission quantity variable means 2, regardless of the presence of absence of the input signal In INF, otuputs the output signal IF OUT of a prescribed level.
|
