| 摘要 |
PURPOSE:To improve the reliability and the economization of a device by adopting the synchronizing pattern detection system and monitoring current multiplexing and demultiplexing parts and stand-by multiplexing and demultiplexing parts by the same method. CONSTITUTION:In case that the current multiplexing part is monitored, a high-speed signal 140 for transmission monitor of the output of a multiplexing circuit 23 which multiplexes plural transmission low-speed signals 10 into one high-speed signalis sent to the stand-by demultiplexing part. When a synchronizing pattern is obtained as the result of detection, a control circuit 94 judges that the current multiplexing part performs the normal operation, and monitoring of the current demultiplexing part is started. If the synchronizing pattern is not detected and stepout occurs, the current multiplexing part is switched to the standby multiplexing part automatically by the control of the control circuit 94. The current demultiplexing part demultiplexes a reception high-speed signal 60 transmitted from a counter station into plural reception low-speed signals by a demultiplexing circuit 52 and transmits them not only to a line through a selecting circuit 51 as reception low-speed signals 40 but also to a pattern detecting circuit 96 of a monitor part 90 as low-speed signals 80 for reception monitor.
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