| 摘要 |
PURPOSE:To improve the quality of talking by dividing a level change region of a channel gain into plural regions in response to the kind of state changeover of transmission and reception to set respectively the control characteristic of the channel gain at each split region. CONSTITUTION:A transmission attenuation circuit 6 is inserted to a transmission line 1, a reception attenuation circuit 7 is inserted to a reception line 2 and a gain control circuit 8 is connected to both the attenuation circuits 6, 7 so as to constitute a voice switch circuit of the channel gain control system. The control circuit 8 compares the voice level of the transmission line 1 and the voice level of the reception line 2, and the control gain of the channel is formed based on the result of comparison and the result is fed to the attenuation circuits 6, 7. The level change region of the channel gain is split to plural kinds in response to the kind of the state changeover of the transmission and reception. A control characteristic of the channel gain is set respectively to each split region and the talking gain is controlled according to the control characteristic. The increasing characteristic having a large change in the control characteristics is set to a curve projected upward to improve the quality of talking. |
