| 摘要 |
PROBLEM TO BE SOLVED: To transmit a part time signal through the use of an inexpensive switch. SOLUTION: An active system low speed interface section 11, a standby system low speed interface section 15, and a P/T system low speed interface section 16 are operated independently by using an active system selection distribution section 12 and a standby system selection distribution section 17. An active system multiplexer/demultiplexer section 13 and a standby system multiplexer/demultiplexer section 18 demultiplex a multiplexed signal received from an active system optical transmission line and a standby system optical transmission line into signals of plural channels, the active system selection distribution section 12 and the standby system selection distribution section 17 provide the demultiplexed signals to respective multiplexer circuits 32b, 42b, 52b of the active system low speed interface section 11, the standby system low speed interface section 15, and the P/T system low speed interface section 16 selectively, the multiplexer circuits 32b, 42b, 52b generate the demultiplexed signals into one multiplexed signal, which is transmitted to a main terminal device 7 and a PHT terminal transmission device 21 via optical transmission reception modules 31, 51, 41.
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