Optical line monitoring method and an apparatus permitting simultaneous

Abstract

An optical line monitoring method and an apparatus for locating a failure point in an optical communication system, wherein a plurality of types of inspection light rays having wavelengths which are determined by cut-off wavelengths, which differ from each other, of short-wavelength pass filters installed at a plurality of branched ports of an optical coupler/splitter of the communication system are sent from a light source having variable wavelengths into one or more corresponding optical fiber lines of the system in sequence via an optical directional coupler and the optical coupler/splitter. Each time reflected light, corresponding to the inspection light, from one or more optical fiber lines is received, an output representing the intensity level of the reflected light is sent from a light receiver to an arithmetic circuit and stored in the arithmetic circuit. The arithmetic circuit calculates the reflected light intensity levels which correspond to the individual optical fiber lines according to the light receiver outputs which individually correspond to inspection light rays, whereby the position of the failure in the optical fiber line incurring the failure is identified.