| 摘要 |
PURPOSE:To improve the quality of talking by giving an output of an AGC circuit provided respectively to a transmission system and a reception system to a transmission loss means and a reception loss means as control inputs respectively so as to decrease the feeling of switching between the transmission state and the reception state. CONSTITUTION:A voice signal inputted from a microphone 1 is sent to a communication line 6 through an amplifier 2, a transmission loss circuit 3, a transmission output amplifier 4 and a hybrid circuit 5. On the other hand, a reception signal sent through the line 6 drives a speaker 10 through a hybrid circuit 5, a reception input amplifier 7, a reception loss circuit 8 and an amplifier 9. Outputs of the loss circuits 3, 8 are fed also to AGC circuits 14, 15 so as to control the loss of the circuits 3, 8 reciprocally. Further, the output of the amplifier 2 and the output of the loss circuit 8 are compared by a comparator 13 and the result of comparison controls reciprocally the loss of the loss circuits 3, 8. Thus, the feeling of switching between the transmission state and reception state is decreased.
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