| 摘要 |
PURPOSE:To eliminate need for an optical terminal station for each line by using a prescribed number of switches so as to control the changeover of a prescribed number of optical transmission lines. CONSTITUTION:Optical switches 7 of NXN=4X4 or the like are provided to optical transmission lines 6 whose number is N=4 and being optical fibers 11. Then switching control circuit 3 always monitors an optical signal on the fibers 11 via a photodetector 2 and the switch 7 is subject to switching control when the absence of an optical signal on the operating fiber 11 as an active line is detected, the optical fiber 11 is connected to an optical terminal station. Thus, no optical terminal station is required for each line and a standby line is not required and quick and sure changeover is implemented and the optical transmission changeover device with high reliability is obtained. |
