Research On Multiplexing Expansion And Wavelength Detection Technology Of Fiber Grating Sensor

Optical fiber sensing technology is a sensing technology that uses optical fiber as a medium and light waves as a carrier to sense and transmit the signal to be measured.Fiber Bragg Grating is widely used in oil pipeline leakage warning,bridge and tunnel structural health monitoring,and high-voltage power transmission line safety due to its many advantages such as low energy loss during transmission,high mechanical strength,and large number of multiplexed sensors.Protection and other fields.With the rapid development of optical fiber sensing theory and its application technology,optical fiber sensing technology is continuously developing in the direction of large capacity,long distance,high precision and networking.Based on the analysis of fiber grating sensing technology at home and abroad,this paper takes large-capacity fiber grating sensing network demodulation technology and system as the research object,and launches preliminary explorations on two key issues of fiber grating multiplexing and expansion and wavelength detection technology Research:(1)Propose an effective denoising scheme and corresponding algorithm improvement for the multiplexing part of the sensor network,and finally realize the multiplexing and expansion of the largecapacity fiber grating network of the sensor network.(2)Perform temperature sensing experiment on fiber grating and detect its wavelength change.The research content and achievements of this paper mainly include:(1)On the basis of summarizing and analyzing the domestic and foreign research work related to fiber grating sensing technology,according to the theory of fiber grating coupled mode,the calculation method and spectral characteristics of fiber grating are studied,and the fiber grating wavelength division/time division hybrid multiplexing model is established.And further explore the causes of crosstalk caused by spectral shadow effects and multipulse interference to sensor signals;(2)On the basis of analyzing commonly used network denoising algorithms,explore new methods of denoising in large-capacity fiber grating network multiplexing systems.A de-noising algorithm combining CEEMDAN and wavelet packet is proposed and verified by simulation.The results show that the proposed algorithm has the characteristics of a complete integrated empirical mode decomposition of adaptive noise and the combination of wavelet packet algorithm.The combination of CEEMDAN and wavelet packet denoising algorithm has a repeatability of 20 consecutive times under 4 different signal-to-noise ratios.The average test error can be reduced by up to 0.245,which has higher reliability and guarantees the accuracy of subsequent demodulation;(3)Designed and built a large-capacity fiber grating sensor network demodulation system test platform.Using the CEEMDAN and wavelet packet denoising algorithm proposed in this paper to build a system after denoising,through the temperature sensing experiment test and analysis of the center wavelength at different temperatures,it shows that the demodulation system is within the temperature range of 5??60?.The average temperature error is greatly reduced to 0.2507?.The research results of the large-capacity fiber grating network multiplexing demodulation system in this paper have certain theoretical and technical reference value for practical engineering applications.