| 摘要 |
PURPOSE:To easily distinguish whether a fault is a fault at a connecting point or a fault of a light receiving section of the next stage repeater by adopting a two-branch structure to a repeater system fiber and applying loopback to a part of a optical output level through the two-branch structure. CONSTITUTION:Two-branch structure fibers 22B, 23A are used as repeater system fibers connecting outputs of incoming and outgoing light emitting devices 4, 9 of an optical repeater 1, and fibers 22, 23 at one end are used as a main relay transmission line. Then branch fibers 221, 231 of the other end are connected to a loopback input of other transmission system and connected respectively to incoming and outgoing 2-input light receiving sections 2, 7 via optical shutters 5, 6 controlled from a terminal station to constitute the optical loopback. Thus, since a part of an incoming optical output level, e.g., is subjected to loopback by the branch fiber 231 after the connection to the fiber 23A, whether a fault is a fault at its connecting point (a) or a fault of the light receiving section of the next stage repeater is distinguished and the faulty location is surely and easily found out. |
