| 摘要 |
PROBLEM TO BE SOLVED: To automatically perform fault location on the way of a path at actual time without altering an optical access system.SOLUTION: An optical line monitoring method monitors, by an OTDR, a loss characteristic change on the way of each path in an optical line system which consists of an optical path formed by one optical fiber and a plurality of paths formed by a plurality of branches, constructed by making the optical path formed by one optical fiber branch out to the plurality of branches by passive optical branching means, and making the plurality of branches formed by optical fibers whose difference between lengths is larger than the distance resolution of the used OTDR. The optical line monitoring method always monitors to compare a current reflection impulse response waveform with a reflection impulse response waveform from a certain time before, and if a decrement response has been detected, it determines a loss occurrence path by a fall position of the waveform of the decrement response, and determines a loss occurrence place by a rise position of the waveform of the decrement response. A digital-type OTDR employing a pseudorandom code correlation system is used. |
