The Key Signal Processing Technology Of Botdr Distributed Sensing Systems

Distributed optical fiber sensing technology can be used to monitor the themeasured information in continuous space and time, it has great prospects fordevelopment. With high measurement precision and long sensing distance, thedistributed optical fiber sensing technique based on Brillouin scattering become themainstream technology in optical fiber sensor field. This paper research the Brillouindistributed optical fiber sensing system in sensing accuracy, sensing distance andspatial resolution problem. The specific contents are as follows.First, expound the mechanism of spontaneous and stimulated Brillouin scatteringand research the quantitative relation between the Brillouin scattering spectrum shift,strength and temperature, strain. Focus on coherent detection technology, and analyzesthe performance of the BOTDR system. Three problems in BOTDR system at thepresent stage, measurement accuracy, spatial resolution, sensing distance, arediscussed.Secondly, in view of the high accuracy need of Brillouin scattering spectrumcenter frequency extraction, research group proposed a Brillouin scattering spectralfitting algorithm PSO-LM algorithm. On this basis for further improvement of thealgorithm, FEA-LM algorithm is proposed in this paper. The simulation results showthat the new algorithm can effectively improve the accuracy of the measurementsystem.Thirdly, in order to improve the spatial resolution of the system, this paper putforward the pulse subdivision stack technology. Theoretical analysis and numericalanalysis results demonstrated that this method can improve the spatial resolutiondepending on the sampling rate, overcome the limitation of the pulse width on thespatial resolution, and can improve the sensing distance simultaneously.Finally, in order to improve the distributed sensing distance, this paper introducesthe Simple coding technology and use it combining with the average superpositiontechnology. Use different encoding and averaging combination with the different requirements in real-time and sensing distance of the system. This method improvesthe sensing distance with guarantee of the space resolution.