Research On The Wavelength Demodulation System Of FBG Based On Virtual Instrument Technology

Optical fiber sensing technology has developed rapidly with the development ofoptical communication technology, and has been widely applied in many areas, such aselectricity,bridges,medical and mine. Existing FBG demodulation products are expensive,bulky.The key is to reduce costs and develop a practical demodulation systems. Thispaper choose fiber Bragg grating(FBG) wavelength demodulation technology as researchsubjects has important academic value and practical significance.This thesis first summarized the basic principle and characteristics of FBG sensingtechnology.The principles and the performance of the four methods are analyzed andcompared. The demodulation system in this paper is based on tunable F-P filter method,the main contents as follows:The characteristics of FBG sensor signal and noise modelwhich generated in optical system have been analyzed. Using LabVIEW and MATLABsimulation software produce a FBG sensor demodulation signal which included noise;according to FBG signal processing:Gathering-Filter-Fitting-location,for the filter, themoving average filtering, wavelet filtering, zero phase filtering, optimized zero-phasefiltering, Savitzky-Golay smoothing filtering and other nine kinds of filtering algorithmshas been simulated and compared; for the fitting, Power weighted average method,Gaussian fitting,deconvolution method Etc have been simulation analyzed. Theadvantages and disadvantages of filter algorithms and peak-detection algorithms wereanalyzed and compared.In order to explore a further accurate detection method of FBG center wavelength,based on neural network theory, design and debugging of RBF, BP and wavelet neuralnetwork, used to fitting spectral data, by comparing the time and results of network andanalyzing and comparing the advantages and disadvantages of different networkstructures.Thr result showed that the neural network fitting has advantages in processingFBG reflection spectrum.Completed the design of FBG wavelength demodulation system based on virtualinstrument technology. And this system operate normally and can process and storage thecollected spectral data. Demonstrate the effectiveness and feasibility of the FBGwavelength demodulation system.