Optical time domain reflectometer with automatic measuring function of optical fiber defects

摘要

A light source (1) supplies an optical pulse to a target optical fiber (6). A light receiver (3) produces an electric signal corresponding to reflection light from the target optical fiber (6). A processor (4) per­forms digital processing on the electric signal to thereby produce waveform data. A level computing sec­tion (7) computes level difference data for a predeter­mined unit interval of the waveform data. A comparator (8) compares the level difference data with a first threshold value and produces reference position data indicating a position where the level difference data exceeds the first threshold value. A detector (9) retrieves that level difference data which is located within a predetermined range preceding and succeeding the reference position data, to thereby detect first and second position data indicating preceding and succeeding constant-value start points, and detect first level data included in the waveform data, which corresponds to a point attained by adding the predetermined unit interval to the first position data, and second level data of the waveform data which corresponds to the second position data. A judging section (10) acquires difference data indicating a difference in level between the first and second level data and determines a defective point in the target optical fiber (6) by comparing the difference data with a second threshold value.