A modified demodulation algorithm for fiber-optic distributed temperature sensing system based on raman scattering

Abstract

A modified demodulation algorithm in the fiber-optic distributed temperature sensing system base on Raman scatter is introduced. It is a combination of wavelet domain denoising and iteration technique which rises the signal to noise ratio(SNR) of the raw data and finely compensate the attenuation difference between Stokes and Anti-Stokes wavelength of the sensing fiber. A 8 km conventional OM1 fiber is used as the temperature sensing fiber and the raw data of demodulated temperature is processed by the wavelet domain denoising method, which enhanced the temperature resolution from 8.0 to 1.0°C in the fiber end, where we got the worst SNR. Further the attenuation difference between the Stokes and Anti-Stokes wavelength is finely compensated by a iteration of 8 times and a temperature resolution of 0.1°C is achieved on a whole fiber of 8 km.