| 摘要 |
PURPOSE:To prevent generation noise at switching of a transmission station by utilizing a frame synchronism detecting signal added to a voice suppressing code and obtained at a receiver inside for voice suppression and also providing a proper time constant to the control of suppression. CONSTITUTION:A voice suppression indication code detecting circuit 1 detects a voice suppression indication code and a frame synchronism detecting circuit 2 performs frame synchronism detection of a PCM signal. Further, a timing control circuit 4 is constituted so as to keep the suppressing state for a prescribed time even if an output signal of an OR circuit 3 is changed from the voice suppressing state into the suppressing state. Thus, in utilizing the output of the frame synchronism detecting circuit 2, most of the period to suppress the voice is controlled by the output of the circuit 3 and further the voice suppressing period is prolonged by the output of the circuit 4, thereby suppressing voice surely. |
