| 摘要 |
PURPOSE:To decrease demodulated noise without deteriorating talking quality by controlling an attenuation of a variable attenuator in response to a reception level and controlling variably the gain of a variable gain amplifier according to the envelope output. CONSTITUTION:A reception level detection circuit 7 detects a reception level by a reception circuit 3 and supplies it to a level control variable attenuator 8. The circuit 8 changes the attenuation depending on the received level. When the reception level is low, the attenuation of the attenuator 8 is increased, the output of an envelope detection circuit 6 is decreased so as to decrease the gain of a variable gain amplifier 5. Since the gain change of the amplifier 5 is set at each syllable of the talking voice in this case, the deterioration of the talking quality due to the gain change is produced and even if demodulated noise is superposed on the talking voice, the deterioration in the talking quality due to the demodulated noise is improved by decreasing the entire output level. |
