| 摘要 |
PURPOSE:To prevent the generation of hawling and noise, by increasing the time constant of an integrated circuit when there is a detecting signal, and decreasing the time constant at the time of no detecting signal. CONSTITUTION:A carrier modulated by a voice signal from a microphone 20a is transmitted 30a to a remote station and a modulated carrier transmitted from the remote station is demodulated 38a and outputted from a speaker 46a. When the modulated carrier is supplied, a carrier detecting signal is generated 64a an integrating circuit in a control circuit 60a integrates the carrier detecting signal and actuates a transmission circuit 30a in accordance with the integrated output signal or a transmission starting signal, and when the transmission starting signal or the integrated output signal disappears, the transmission circuit 30a is disabled. The integrated time constant is controlled so as to be increased at the generation of a detecting signal and decreased at the disappearance of the detecting signal. |
