Optical fiber distributed temperature sensor using short term Fourier transform based simplified signal processing of Raman signals

A simplified technique using short term Fourier transform to reduce the errors in distributed temperature measurement with a Raman scattering based optical fiber sensor system is presented. The two main sources of errors are differential attenuation to anti-Stokes and Stokes signal by fiber and local change in Stokes due to change in temperature. The proposed technique compensates these errors and extracts correct temperature profile in spite of practical difficulties encountered in applying the theoretical concept. Moreover proposed technique is less complex, self-reliant, can tolerate variation in laser power, requires less dead zone and suits automation using embedded solution. Results of measurement carried out, using the system developed at RRCAT, Indore, for two hot zones having spatial width of 1.9 m ( kept at 56 degrees C) and 1.5 m ( kept at 78 degrees C), located at 47 m and 85 m respectively, show that these parameters can be recovered with significantly small errors. (C) 2013 Elsevier Ltd. All rights reserved.