| 摘要 |
PROBLEM TO BE SOLVED: To obtain a PDS optical line supervisory system capable of specifying an abnormity point in a plurality of subscriber side transmission lines with one testing device. SOLUTION: A test pulse light from an OTDR 2 is given to a 1:n optical multiplexer/demultiplexer 5, where the light is demultiplexed into (n) signals, the signals are sent to each subscriber home through an optical fiber grating 6. In the transmission characteristic of the optical fiber grating 6, the light of band other than that of the test pulse light is passed, and the band of the test pulse light is blocked. However, only a light with wavelength bands of λ1, λ2,..., λn different from each subscriber is transmitted. In this characteristic, the test pulse light transmitted through the optical fiber grating 6 is scattered in an optical transmission line 7 or part of the light is returned in a direction of an in-station device 9 through reflection at a fiber connecting point or an abnormity point. The returned light is analyzed to locate at which point of which path of the optical transmission lines 7, a fault takes place. |
