Research On High Accuracy Extraction Of BOTDR Distributed Sensor Signal Based On Improved D-S Evidence Theory

The distributed optical fiber sensing technique based on Brillouin scattering can carry out the continuous monitoring of fiber features along with time and space. It can be widely used in the field of long fiber sensing. Based on the linear relation between the temperature and stress change of the optical fiber and Brillouin center frequency shift, the technique can realize directional sensing and obtain optical fiber information outside. The paper concentrates on high accuracy extraction of distributed sensor signal to spread related research. The details are as follows:Firstly, this paper briefly describes the classification of distributed optical fiber sensing technology. And the current situation of fiber optic sensing technology based on Brillouin scattering is studied in this paper. The mechanism of spontaneous and stimulated Brillouin scattering is analyzed. The mechanism of spontaneous and stimulated Brillouin scattering is also analyzed. At the same time he linear relationship between frequency shift of Brillouin center, optical power and temperature, strain is described. Finally, this paper briefly describes the principle and characteristics of different Brillouin signal detection techniques.Secondly, a new method based on adaptive chaotic particle swarm optimization(AIW-CPSO) algorithm is brought forward. The algorithm introduces the adaptive inertia weight parameter. And the stochastic nature and ergodic property nature of chaos optimization are used to improve the standard PSO algorithm. The AIW-CPSO algorithm overcomes the defects of the premature convergence of PSO and makes it jump out of local optimum. Simulation results show the proposed algorithm is applied to the fitting of Brillouin scattering spectrum with different linewidth, different SNR and different linear weight ratio. Then high accuracy of feature extraction and temperature information can be obtained.Finally, the basic concepts, principles and fusion rules of D-S evidence theory are described, and an improved D-S evidence theory algorithm is proposed. Combine the improved D-S algorithm with AIW-CPSO,and apply it to the Brillouin scattering spectrum feature extraction. The contrastive analysis and simulation results show that DS-AIW-CPSO can improve the extraction accuracy of Brillouin center frequency shift and temperature information obtained by DS-AIW-CPSO algorithm are both higher than that of AIW-CPSO. And it improves the stability of feature extraction algorithm in Brillouin scattering spectrum.