Empirical mode decomposition based dynamic error correction in SS covered 62.5/125 mu m optical fiber based distributed temperature sensor

• Published in: Optics and laser technology 2015-04, Vol.67, p.107-118
• Main Authors: Saxena, Manoj Kumar, Raju, SDVSJagannadha, Arya, R, Pachori, R B, Ravindranath, SVG, Kher, S, Oak, S M
• Format: Article
• Language: English
• Subjects: Covering; Detection; Error analysis; Fibers; Optical fibers; Permissible error; Stainless steels; Temperature sensors
• ISSN: 0030-3992
• DOI: 10.1016/j.optlastec.2014.10.006

The design and implementation of empirical mode decomposition (EMD) based preprocessor for backscattered spontaneous Raman anti-Stokes (AS) and Stokes (St) signals obtained from a stainless steel (SS) covered, 62.5/125 mu m optical fiber based distributed temperature sensor is presented. The preprocessor dynamically minimizes the error in temperature measurement caused by the difference in attenuation to AS and St signals offered by the optical fiber. Simultaneous denoising of AS and St signals obtained by the EMD based preprocessor yields better signal to noise ratio (SNR) of these signals and allows reduced error in temperature measurement. The EMD based technique is much better than previously reported techniques in terms of simplicity and automation. Automated and dynamic self calibration of distributed temperature sensor is also possible with the proposed preprocessor in an easier way. The use of proposed preprocessor has been demonstrated to develop an optical fiber based distributed temperature sensor with an accuracy of plus or minus 2.5 degree C in a temperature range of 25-105 degree C over a sensing length of 90m with a spatial resolution of 1m. The developed system uses a rugged stainless steel (SS) covered 62.5/125 mu m Multimode optical fiber. SS covering on the fiber makes it easier and safer to install the sensing fiber in critical field locations where normal sensing fiber cannot be used.