The Envelope Algorithm Research Of BOTDR Signal

This dissertation mainly achieve the digital signal process of fiber sense signal with coherent detection.Firstly, we introduce the principle and applications of distributed fiber sense system, then analyze the latest time-frequency analysis technical in digital signal process domain and some common algorithms for complex signal process.Next we introduce the sense principle of Brillouin scattering and propose the scheme of Brillouin distributed sense system.The characteristic of Brillouin sense signal is wideband modulated and added by lots of random noises, so the dissertation process the BOTDR signal with envelope algorithm based on Morlet. We choose the algorithm's parameters which can effect the envelope result obviously and analyze, simulate the BOTDR signal, moreover identify that the sense system's performance has been improved.We research the S transform which is newly developed in last decade. Through comparing the S transform with short time Fourier transform and Morlet wavelet transform in time-frequency domain, we find out that the distinct advantage of S transform. Because S transform choose the constant mother wavelet function, we introduce the generalized S transform and compare it with S transform. Then we envelope the BOTDR signal using S transform and generalized S transform separately, we get better result by adjusting the parameter of generalized S transform.At last we summarize the dissertation and point out the advantages and disadvantages using S transform to envelope the BOTDR signal, then we know how to improve performance of the algorithm.