| 摘要 |
PURPOSE:To prevent an alarm from being transmitted to a multiplexer in standby as a spare device as if a fault were caused in said device by transmitting a pseudo reception signal to the multiplexer in standy as the apare. CONSTITUTION:Terminal devices 1, 2 are connected through two transmission lines via switching circuits 3, 4 so as to be selected for exchange connection. The transmission lines consist of multiplexers 5, 5', dial signal transmitters 6, 6', multiplexers 7, 7', dial signal transmitters 8, 8' and an exchange network 9. A pseudo signal is transmitted to a multiplexer in standby as a spare so that no faulty alarm of the transmission line is fed to a multiplexer in standby as a spare among the multiplexers 5, 5' and 7, 7'.
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