| 摘要 |
PURPOSE:To suppress influence given by an asynchronous state by providing a comparator and a relay, and a performing bypass control while monitoring a source voltage. CONSTITUTION:An input signal is bi-sected by an optical branching filter 2, and one is supplied to an optical switch 1, and the other to the logic part 22 of data transmission equipment 2, and the output of the logic part 22 is issued to an optical fiber cable L' via the switch 1. A driving power source for the switch 1 is supplied from a power source 21 via the contact of the relay 4 excited by a transistor(TR) 11 being turned on by the comparator 10 which compares a reference voltage generated from the power source 21 of the branching filter 2 with the output of the logic part 22. The bypass state of the switch 1 can be formed when the power source 21 is disconnected, etc., and the TR 11 is turned off just before an error occurs in the logic part 22, and the relay 4 is recovered. After that, the output of the logic part 22 via the contact 4a of the relay and a time constant circuit is supplied to the comparator 10 when the power source 21 is supplied, and the power source 21 is supplied after a synchronous stable state is established. |
