Abstract: A filter processing system making it possible to be able to set a frequency pass-band automatically and to provide the optimum filter to an input signal. A filter processing method of an output signal of an Optical Time Domain Reflectometer (OTDR) in a chromatic dispersion distribution measuring apparatus is disclosed. The filter processing method includes establishing measuring-condition parameters, generating an ideal signal waveform based on previously established chromatic dispersion values and the measuring-condition parameters, and providing correlation results between the ideal signal waveform and a filter input signal. The method also includes comparing the correlation results to a threshold value to generate a minimum chromatic dispersion value and a maximum chromatic dispersion value, and performing filter processing for the output of the OTDR based on the minimum chromatic dispersion value and the maximum chromatic dispersion value.

Abstract: In order to improve a measuring precision in case of measuring properties of the optical fiber to be measured, in accordance with returned lights which have wavelengths different from each other, detection is carried out with respect to the returned lights of the wavelengths different from each other, at a timing based on difference of propagation rates between the returned lights in the optical fiber to be measured, and error between the returning points is compensated with respect to each returned light, in the optical pulse testing device for inputting the optical pulse to the optical fiber to be measured, to detect returned lights which have wavelengths different from each other and which are returned back from passing points in the optical fiber to be measured, respectively, in order to measure the properties of the optical fiber to be measured, in accordance with detection results of the returned lights.

Abstract: A light source produces laser beams that are subjected to frequency modulation whose frequency can be adequately set or varied. A light modulator modulates laser beams with respect to the center wavelength, so that the lower sideband is used as probe light input into one end of the measured optical fiber. A pulse modulator produces laser pulses based on laser beams as pump light, which is input into the other end of the measured optical fiber, along which correlation peaks emerge at different positions. The output light is extracted from the other end of the measured optical fiber and is supplied to a timing adjuster, which adjusts a transmission timing to allow transmission of light proximate to a measuring point in the measured optical fiber therethrough. Thus, it is possible to reliably measure characteristics of the measured optical fiber entirely over the relatively long distance with high spatial resolutions.