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

[Display omitted] •Optical fiber distributed temperature sensor with STFT technique is presented.•Accuracy in temperature measurement is achieved by STFT of Raman signals.•Automatically adjusts signals in spite of the several practical difficulties.•Tolerates variation in ‘laser power’ and/or ‘coupling between laser and fiber’.•Hot zones of 1.9m (56°C) and 1.5m (78°C) at 47m and 85m were measured. 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 1.9m (kept at 56°C) and 1.5m (kept at 78°C), located at 47m and 85m respectively, show that these parameters can be recovered with significantly small errors.