The Researching On Signal Processing Methods Of Brillouin Distributed Sensing System

The distributed optical fiber sensing technology can simultaneously measure the timeand space domain along the fiber for the distribution of information to achieve a full rangeof continuous monitoring of the measured field, it becomes the current popularresearching field. The distributed optical fiber sensor based the Brillouin scattering cansupport long-distance temperature and strain sensing at the same time, so it has very broadprospects for future development. This paper mainly researches signal acquisition and dataprocessing methods about the distributed optical fiber sensor system based Brillouinscattering. The main content in this paper including：Firstly, this paper introduces Brillouin scattering, OTDR theory and optical fibersensing system. It researches theoretically on the relationship between Brillouin frequencyshift and the light intensity and sensing performance parameters like temperature andstrain and conducts the equation investigated theoretically, and derivation of the frequencyshift of light intensity and temperature the relationship between them.Secondly, this paper provides signal processing approach according to Brillouinscattering and acquire the approach of extracting week signal characteristics under thenoise background by using the digital average cumulative method. It also presents in detailand take full use of the theory of the average cumulative to improve the SNR and decreasenoise.Thirdly, it studies deeply on Brillouin sensor signal demodulation method andestablishes the model of demodulation. The principle of fiber optical sensing based on theeffect of Brillouin optical time domain reflectometry is established in this paper. Using theMorlet wavelet transform of digital signal average cumulative envelope detector. Itextracts power data at different frequencies along the fiber, and fits them with MATLAB,so it can affirm Brillouin frequency shift and obtains the data of temperature and strain. Itis given that MATLAB simulation results included digital average cumulative denoising,the Morlet wavelet transform of the envelope detector and Brillouin scattering spectrum ofthe model based on Lorentz function fitting in this article. Finally, it illustrates the signal acquisition and data processing and experimentalsection. In this section, it describes three aspects: the technical indicators of thecomposition of the sensing system, the hardware and the software composition of thesignal acquisition and processing system, and it’s workflow. It pays attation to theselection of data acquisition card, function testing, the analysis of antiinterference abilityand staff and the consequence of the whole system.