Dynamic range enhancement of OTDR using lifting wavelet transform-modified particle swarm optimisation scheme

Abstract

The optical time domain reflectometry (OTDR) is the only investigation tool for the optical fibre continuity measurement and is capable of verifying inline splices and locating fibre faults. As per the literature review, most of the distributed fibre sensors are designed using OTDR principle. Dynamic range plays a major role in such instruments. Dynamic range enhancement of OTDR is proposed using the lifting wavelet transform (LWT)-modified particle swarm optimisation (MPSO) scheme. This scheme enables us to design customised lifting wavelet filters to improve the signal-to-noise ratio which in turn improvises the dynamic range. This study proposes and demonstrates the application of LWT along with the MPSO evolutionary algorithm to obtain optimum threshold, in order to mitigate the noisy lifting wavelet coefficients effectively. The proposed scheme is employed for OTDR measurement up to 50 km (silica optical fibre), using 10 dBm of laser input power. As compared with the conventional wavelet regularised deconvolution schemes, the authors’ proposed scheme offers a 3.42 dB enhancement in the dynamic range under a lower computational complexity requirement. The proposed study is carried out using computer simulation using MATLAB 15.0 software. The results were experimentally validated.