Optical fiber testing method for measuring connection location and

Abstract

In an optical fiber testing method, light are supplied to a measuring optical fiber so that return light, consisting of back-scattering light and Fresnel-reflection light, is outputted from the measuring optical fiber. A waveform representing the return light is used to perform testing of the measuring optical fiber. Herein, a detection range of the waveform used for detection of connections is defined and is partitioned into a plurality of regions in connection with Fresnel-reflection space. Then, at least a noise index and a constant are calculated for each region; and HOUGH conversion is performed on each region of the waveform. In addition, a center-value filtering process is performed, using the constant, with respect to each region of the waveform to create a filtered waveform. Further, a mean difference process is performed on the filtered waveform to create a mean difference waveform. A location of a temporary connection is set at a specific location of the mean difference waveform whose level exceeds a predetermined range. Approximate lines are calculated with respect to a left-side section and a right-side section of the temporary connection on the mean difference waveform. A connection loss is calculated for the temporary connection based on the approximate lines. Then, a decision is made, based on the connection loss, as to whether or not the temporary connection indicates a real connection. Thus, it is possible to automatically detect locations of connections and connection loss with high precision.