| 摘要 |
PURPOSE:To mute the undesired passing sounds that are outputted through a speaker of a cordless slave device with operations of such switches as an on-hook switch, an unlock switch, a holding switch, etc. CONSTITUTION:A master device radio circuit 4 transmits the carrier that is modulated by a down-voice signal, and the carrier under transmission through the circuit 4 is interrupted with push of a switch which has such functions as the on-hook, unlock, holding, etc. Then a control signal transmitter circuit 6 sends the control signal to a slave device via the circuit 4 in accordance with each function. A slave device radio circuit 14 receives the control signal as well as the carrier modulated by the down-voice signal. Then the control signal is received by a control signal receiver circuit 16, and the modulated carrier is received by a carrier sensor circuit 17 respectively. A muting circuit 18 mutes the control signal when the carrier received by the circuit 17 is interrupted. |
