| 摘要 |
PURPOSE:To prevent the generation of reception noise at switching by inserting a pattern different from a synchronizing pattern for a prescribed period before switching at the switching of a PCM transmission signal, and applying muting for the period where no synchronizing signal is detected at the receiving side. CONSTITUTION:A pulse-code-modulated information signal is blocked for each prescribed period, and the synchronizing signal of a prescribed pattern is inserted to the block and transmitted. A switch 40 is operated at the transmission side for a prescribed time before the switching at the switching of a transmission signal in this case, the control signal is applied to a block synchronizing signal pattern generating circuit 15 from a switching control signal generating circuit 41, and an error pattern not being a block synchronizing pattern is added at each block at the circuit 15. Muting signals MT, MT' are transmitted to a signal processing circuit 29 from a block synchronizing signal generator 30 and a carrier regenerating circuit 28 at the receiving side for a period where no synchronizing signal is detected at the transmission, the operation of the circuit 29 is stopped, and when the synchronism is taken, the signals MT, MT' are stopped to release the muting. |
