Yokogawa Electric Corporation

Mitsubishi Electric Corporation

Hideo Shida

Susumu Takahashi

Akira Ishikawa

Kazushi Oishi

Yo Makita

Takashi Iitsuka

Takeshi Kurosaki

Shinji Monden

An optical fiber temperature distribution measurement system includes a temperature difference calculator configured to calculate a temperature difference between corresponding spatial resolution zones based on a first temperature distribution obtained by a return light from a first optical fiber part and a second temperature distribution obtained by a return light from a second optical fiber part, and an abnormality detector configured to calculate a temperature difference for evaluation for each spatial resolution zone, the temperature difference for evaluation being a sum of a temperature difference of each spatial resolution zone and a temperature difference of a spatial resolution zone adjacent thereto, and to determine that an abnormality has occurred in a roller near the spatial resolution zone when the calculated temperature difference for evaluation exceeds a reference value.

Optical fiber temperature distribution measurement system and optical fiber temperature distribution measurement method

An optical fiber temperature distribution measuring device includes: an optical fiber as a sensor; a calculation control unit for measuring a temperature distribution along the optical fiber by using backward Raman scattered light from the optical fiber; a far-end-position dispersion characteristic calculation unit for obtaining a dispersion characteristic of the optical fiber at a far-end position thereof; a per-unit-length dispersion characteristic calculation unit for obtaining a per-unit-length dispersion characteristic of the optical fiber based on the dispersion characteristic of the optical fiber at the far-end position thereof; and a correction parameter calculation unit for calculating a correction parameter for correcting a dispersion characteristic of the optical fiber based on a dispersion characteristic at each of different positions along the optical fiber.

Optical fiber temperature distribution measuring device

An optical fiber temperature distribution measurement device for measuring a temperature distribution along a longitudinal direction of an optical fiber is provided. The device includes: a light transmitter configured to input a train of code-modulated light pulses into the optical fiber; a light receiver configured to receive Raman back scattering lights generated by inputting the train of code-modulated light pulses into the optical fiber; a demodulator configured to perform a correlation processing between a measured signal output from the light receiver and a code string associated with a type of the code modulation performed by the light transmitter, and to demodulate the measured signal; a storage storing a correction data to be used to correct a distortion of the measured signal output from the light receiver when an impulsive pulsed light is output from the light transmitter; and a corrector configured to perform a correction to one of the measured signal output from the light receiver and a demodulated signal output from the demodulator, using the correction data stored in the storage.

Optical fiber temperature distribution measurement device and method of measuring optical fiber temperature distribution

An optical fiber temperature distribution measurement device configured to receive Raman back scattering lights obtained by inputting a pulsed light into an optical fiber and to measure a temperature distribution along a longitudinal direction of the optical fiber is provided. The device includes a first filter device. The first filter device includes: a threshold value setting circuit configured to set a threshold value in accordance with a change in an amount of noise overlapped with a measured signal, the measured signal indicating one of an intensity distribution and a temperature distribution of the Raman back scattering lights along the longitudinal direction of the optical fiber; a filter configured to eliminate a frequency component of the measured signal, the frequency component being larger than a predetermined first frequency; a determination circuit configured to determine if the measured signal is over the threshold value; a synthesizing circuit configured to select and synthesize one of the measured signal processed by the filter and the measured signal unprocessed by the filter in accordance with a determination result from the determination circuit.

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Musashino, Japan

Hideo Shida