Hitachi Cable, Inc.

The Tokyo Electric Power Company, Incorporated

Nobuo Ando

Akiji Shibata

Satoshi Yamamoto

Toshio Fukahori

Hiroyuki Kunugiyama

Yasuo Ozawa

Hiroshi Kawakami

Keiichi Hashiba

Shigehiro Endoh

Kouichi Sugiyama

Akira Tokushima

Kaoru Yamazaki

Teruaki Tsutsui

A method of receiving wavelength multiplex signals is designed to receive together, at an end of an optical fiber transmission path, optical information signals transmitted in multiple wavelengths, which correspond to multiple kinds of information, from a plurality of information sources distributed at a virtually constant interval along the transmission path in response to an optical trigger signal. Each of the optical information signals is sampled at a time interval that is in inverse proportion to the light velocity which depends on the wavelength of the signal, so that the content, kind and source of information are identified at the signal reception.

Method of receiving wavelength multiplex signals

A fiber optic distributed temperature sensor system outputs a temperature distribution along the longitudinal direction of a sensor optical fiber by measuring the temperature dependency of Raman scattered light intensity produced in an optical fiber by use of the OTDR technique. The system is characterized in that a light output from a light source is input to the sensor (optical fiber) via an optical wavelength division demultiplexer, that among the reflected light of back scattered light returning from the sensor optical fiber, light of a particular wavelength range is reflected or transmitted by at least one optical filter of the optical wavelength division demultiplexer to separate the light of the particular wavelength range and that signal of the light of the particular wavelength range is guided to a detector of an optical measuring system.

Fiber optic distributed temperature sensor system

Growing community of inventors

Hitachi, Japan

Nobuo Ando