| 摘要 |
PURPOSE:To search for a fault point of the optical fiber line which has a branch by making a light pulse incident, converting its reflected light after back scattering photoelectrically and performing signal processing, and observing the relation between the distance of the reflection point and reflected light intensity as a reflected waveform. CONSTITUTION:The light from a light pulse generator 11 is sent out to an optical fiber line 2 to be tested through a directional coupler 12. Return light due to the back scattering and Fresnel reflection on the line is converted by a photoelectric converter 14 into an electric signal, which is sent to a processing part 15, which multiplies the delay time after the pulse transmission by its propagation speed to calculate the distance. The result is displayed on a display part 26 while the distance is set on the lateral axis and the signal intensity (reflection quantity) is set on the longitudinal axis. At this time, a step is generated on the reflected waveform at the same distance from the break point and loss increase point of the line. Consequently, the fault point on the optical fiber line which has the branch can be searched for by a specific decision system. |
