Research On Signal Demodulation Technology Of Optical Fiber Sensor Vibration System

Distributed optical fiber sensing systems are popularized in the perimeter security of today's oil and gas pipelines,communication cables and other infrastructures due to their high sensitivity and large monitoring range.The optical fiber sensor is mainly composed of an optical physical system and a digital signal processing system;the first part of the optical physical system is responsible for acquiring external disturbances and transforming into detectable signals;the second part is responsible for signal analysis and processing.The signal processing part plays an important role here,and many defects in the optical physical system can be corrected by the digital signal processing system in practical applications.Therefore,this paper will focus on the signal processing aspects of fiber optic sensing technology.This paper first introduces the research status of optical fiber sensing system and the research status of phase demodulation technology.Through the experimental comparison of common fiber interference structures,an improved distributed dual Mach-Zehnder interference fiber sensing structure is proposed..Based on the above sensing structure,the noise characteristics and polarization fading of the dual Mach-Zehnder system are modeled and simulated.The simulation results verify the assumption that polarization fading is treated as visibility multiplicative noise.The advantages and disadvantages of phase generation carrier technology and traditional 3x3 coupler demodulation demodulation methods are compared by experimental simulation.A 3x3 coupler demodulation algorithm based on ellipse fitting is proposed.The ellipse fitting results are simulated for polarization fading.It is pointed out that the key to ellipse fitting is how to accurately obtain the outer contour of the ellipse.By comparing the wavelet decomposition reconstruction method Compared with the traditional morphological denoising method,the morphological polarization processing method based on elliptical interpolation filtering is proposed.The data acquisition module,noise reduction processing module and signal demodulation module based on Lab VIEW and MATLAB hybrid programming are designed.Finally,the experiment of signal demodulation of fiber-optic vibration sensing system is designed.Combined with experimental data,the effectiveness of the method is proved and the accuracy of signal demodulation is improved.