PURPOSE: To detect reflection type discontinuity with high sensitivity by impressing a light pulse on light waveguide fiber from an optical time domain reflectiometer(OTDR), generating amplitude values at a set of data points corresponding to the detected reflected light, and relating the amplituide values to each other by a predetermined waveform. CONSTITUTION: A light pulse is impressed on optical fiber from an OTDR, and amplitude values are generated at data points corresponding to its reflected light. These amplitude values are precorrected so as to compensate a difference between a noise spectrum and a white noise according to a noise spectrum characteristic of the amplitude values. Reflection type discontinuity is detected by relating the amplitude values to each other by a predetermined waveform. It is desirable that the waveform to be used is obtained by leveling a OTDR trace from fiber having known unexpected reflection of various amplitudes, for example, an amplitude of a range up to about 0.25dB from about 0.58dB to a straight line component of the OTRD trace.
METHOD FOR DETECTION OF REFLECTION-TYPE DISCONTINUITY IN OPTICAL WAVEGUIDE FIBER