Fiber Bragg Grating Temperature System Of Power Cables Based On DSP Signal Demodulation Technology

Fiber Bragg Grating sensor is a photosensitive material which creat spatial phase grating in the core of a fiber,thereby changing and controlling the spread of light in the fiber. FBG sensor is a passive filter pieces with the advantage of small size, fast response, free from electromagnetic interference, corrosion-resistant and easy to reuse.It's used widely in civil engineering structures, aerospace industry, shipping industry, shipping, oil and chemical industry, medicine, nuclear industry, Particularly temperature monitoring of electrical equipment.This paper introduces the basic sensing principle of FBG sensors. Analysis of the various demodulation of Fiber Bragg Grating, summarized the various characteristics of demodulation methods and compared them. A method of providing fitting data based on fiber interleaver filter which to replace reference-grating is proposed.Least square method is utilized to fit linear dependency between bragg wavelength of fiber grating and tuning voltage of Fabry-Perot filter.With wavelength shift that is demodulated by the tunable Fabry-Perot filter,the system accurately detect the displacement of reflection light peak of FBG sensors. And with the analysis of both theory and MATLAB simulations, the paper verify the feasibility of the method in sensing signal demodulation.According to the specific requirements of algorithm and data processing,DSP chip (TMS320VC5416) can meet the actual needs. With the external circuit design of DSP chip, completed the production of hardware. In the design of hardware, completed the core algorithm and software hardware-related programming using C language. The use of analog signal data implement the least-squares fitting algorithm on the hardware. Transfer results is displaied on the PC through the serial communication interface. The result of the research shows that fiber interleaver filter can replace the reference-gratings which is in thermostatic environment to calibrate the wavelength shift. The system meets the engineering application requirements of small error for reflective wavelength measurement. Solved the cost and technology difficulties due to a large number of reference grating.