编码瑞利BOTDA系统传感技术研究

发布时间：2018-05-08 10:45

本文选题：布里渊散射 + 瑞利散射　；参考：《华北电力大学》2017年硕士论文

【摘要】：本文介绍了分布式光纤传感技术的发展背景和现状,主要阐述了布里渊光时域分析(BOTDA)的研究现状,论述了光纤中的布里渊散射特性,揭示了其与温度和应变的关系。分析了基于编码的瑞利BOTDA的传感理论及性能,并对编码瑞利BOTDA实验系统进行了研究与设计。首先针对编码瑞利BOTDA系统中的编码技术即格雷码和Simplex(简称S)码技术进行了简单介绍,分析其编解码原理;深入研究格雷码和S码在瑞利BOTDA系统中的实现方法,并对编码瑞利BOTDA系统的信噪比改善量进行了理论分析和仿真验证。其次分析了基于雪崩光电二极管(APD)检测和S编码的瑞利BOTDA系统中的两种噪声,随机散粒噪声和热噪声。随机散粒噪声功率和信号功率有关,而热噪声功率主要取决于APD光电检测器的性能、与信号功率无关。由系统中与两种噪声相关的电流波动的方差和S码的编解码规则可得编码系统的均方误差,由此推导了系统信噪比和编码增益公式,并利用MATLAB进行了仿真验证。最后设计了格雷码瑞利BOTDA实验系统,重点设计的部分是系统的编解码部分。在设计编码系统前先进行了单脉冲编码瑞利BOTDA系统的设计和测量。理论分析了受激布里渊散射(SBS)瞬态耦合波方程对非归零(NRZ)码和归零(RZ)码系统中声波场幅度和布里渊增益的影响,进行了NRZ和RZ的格雷码瑞利BOTDA系统的实验研究。
[Abstract]:In this paper, the development background and present situation of distributed optical fiber sensing technology are introduced, the research status of Brillouin optical time domain analysis (BOTDA) is mainly described, the Brillouin scattering characteristics in optical fiber are discussed, and the relationship between Brillouin scattering and temperature and strain is revealed. The sensing theory and performance of coded Rayleigh BOTDA are analyzed, and the experimental system of coded Rayleigh BOTDA is studied and designed. Firstly, this paper introduces the coding technology of Rayleigh BOTDA system, that is, Graycode and Simplexcode, analyzes the encoding and decoding principle, and deeply studies the realization method of Gray-code and S-Code in Rayleigh BOTDA system. The improvement of signal-to-noise ratio of coded Rayleigh BOTDA system is analyzed theoretically and verified by simulation. Secondly, two kinds of noise, random shot noise and thermal noise, in Rayleigh BOTDA system based on avalanche photodiode detection and S-coding are analyzed. The random shot noise power is related to the signal power, while the thermal noise power mainly depends on the performance of the APD photodetector and is independent of the signal power. The mean square error of the coding system can be obtained from the variance of the current fluctuation associated with two kinds of noise and the encoding and decoding rules of the S-code. The formulas of the SNR and the coding gain of the system are derived and verified by MATLAB simulation. Finally, a Gray-Rayleigh BOTDA experimental system is designed, the key part of which is the coding and decoding part of the system. The design and measurement of monopulse coded Rayleigh BOTDA system are carried out before the design of coding system. The effects of transient coupled wave equations of stimulated Brillouin scattering (SBS) on the amplitude of acoustic field and Brillouin gain in non-return-to-zero (NRZ) and return-to-zero (RZ) codes are analyzed theoretically. The experimental study of Gray-Code-Rayleigh BOTDA system of NRZ and RZ is carried out.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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