| 摘要 |
PURPOSE:To prevent excessive loudspeaking by converting and negative-feeding back a transmission signal into a control signal and to suppress a slight tone simply with a variable gain adjuster. CONSTITUTION:A transmission signal outputted from an amplifier 19 is transmitted to a line 5 and given to a control signal generator 20, a transmission signal is converted into a control signal with a control signal generator 20 and negative-fed back to a variable gain adjusting circuit 18 to control the output level of the amplifier 19 to a constant value. On the other hand, a transmission signal leaked to the reception system with the coupling 12 between the transmission and reception systems flows to the reception system as the reception signaln and amplified at an amplifier 21, this output is given to the control signal generator 20, this is converted into a control signal and negative-fed back to the variable gain adjusting circuit 18. This controls the output level of the amplifier 19 accordng to the amount of coupling between the transmission and reception systems via a hybrid circuit 4. |
