OPTICAL FIBER MONITOR USING OPTICAL TIME DOMAIN REFLECTOMETER AND MONITORING METHOD

摘要

In order to automatically monitor a to-be-monitored optical fiber with accuracy even if a signal level variation occurs in an OTDR apparatus body due to an ambient change, etc., first to fourth initial data memories 31a to 31d prestore initial data R obtained when a reference optical fiber 22 having a predetermined length was previously measured, and initial data Pa to Pc obtained when the to-be-monitored optical fiber was previously measured. A first arithmetic unit 33 finds a difference alpha between measurement data R' obtained when the reference optical fiber 22 is newly measured and the initial data R as a first drift amount representing a variation in characteristics of the OTDR itself. A second arithmetic unit 34 finds a difference beta between measurement data P' obtained when the to-be-monitored optical fiber 1 is newly measured and the initial data of the to-be-monitored optical fiber as a second drift amount representing a variation in characteristics of the OTDR itself and characteristics of the to-be-monitored optical fiber 1. A third arithmetic unit 35 finds, from a difference between beta and alpha , a real characteristic variation amount gamma of the to-be-monitored optical fiber 1 as a third drift amount representing a variation in characteristics of the to-be-monitored optical fiber 1. A waveform comparator 36 detects the presence/absence of abnormality of the to-be-monitored optical fiber 1 based on the real characteristic variation amount gamma of the to-be-monitored optical fiber 1 which provides the third drift amount. <IMAGE>