| 摘要 |
PURPOSE:To decrease demodulated noise without deteriorating talking quality by outputting an average value signal over a prescribed period of a control voltage to control the gain of a variable gain amplifier. CONSTITUTION:A reception level is detected by a reception level detector 9 and supplied to a voltage comparator circuit 6. A reference voltage is fed to a terminal 10 of the comparator 6 and when the reception level is lower than the voltage, the control voltage decreasing the gain of the variable gain amplifier 8 in response to the reception level is generated and supplied to an average value detecting circuit 7. The circuit 7 measures the control voltage for a prescribed period and supplies its mean value to the amplifier 8 to control the gain. Since the gain change is set at each syllable of talking voice, the deterioration in the talking quality attended with the gain change is eliminated and even if demodulated noise is superposed, the deterioration in the talking quality due to demodulated noise is improved by decreasing the entire output level.
|
