Design and Development of Fiber Optic Sensor for Remote Monitoring

Abstract

A fiber optic sensing system is suitable for detecting surrounding environmental newlineparameters like temperature, strain, vibration, intrusion, acoustic effects, etc. The fiber optic newlinesensing system that allows continuous, real-time measurements along the entire length of an newlineoptical fiber is known as a distributed fiber optic sensing (DFOS) system. Most of the DFOS newlinesystems designs are based on the principle of optical time-domain reflectometry (OTDR) and use newlinethe backscattering effects like Rayleigh, Brillouin, and Raman scattering effects. Sensing range, newlinesensing resolution, spatial resolution, and power consumption are the major performance metrics newlineof a given DFOS system. In this thesis, the dynamic range improvement of OTDR using the newlinedifferent signal processing techniques is reported. The respective results are experimentally newlineevaluated. newlineThe performances of fiber-based distributed sensing systems are investigated using newlinedifferent signal processing techniques namely using translation invariant wavelet thresholding newline(TIWT), lifting wavelet transform-modified particle swarm optimization (LWT-MPSO), LWToptimum newlinemodified differential threshold (LWT-OMDT), and empirical mode decomposition newline(EMD) techniques. In this thesis, distributed temperature sensing (DTS) systems namely newlineBrillouin OTDR-DTS, Brillouin OCDR-DTS, and distributed strain sensing (DSS) systems newlinenamely Brillouin OTDR-DSS, Brillouin OCDR-DSS, and Rayleigh OTDR-DSS are investigated newlinefor their performance improvement using the adopted signal processing techniques. newlineThe higher degree of sensing resolution with a higher degree of sensing range is obtained newlinein the Brillouin OTDR-DTS system using EMD, and LWT-OMDT techniques. As compared to newlinethe EMD technique, the LWT-OMDT technique offered better performance. The higher degree newlineof temperature resolution along with a sub-meter spatial resolution is obtained in the Brillouin newlineOCDR-DTS system using the PSO technique.