Research And Design Of General Demodulation System For FBG Sensor And Fiber F-P Sensor Based On DSP

Nowadays, optical fiber sensor is one of the most popular research hotspot in sensing. For large-scale projects monitoring, comprehensive compared with all of intelligent sensors, as can be seen, optical fiber sensor is the best choice in monitoring conditions of civil projects. In a variety of fiber optic sensors, Fiber Bragg Grating (FBG) sensor has the advantage of wavelength encoding, easy multiplexing and real-timing. Fiber Fabry-Perot (FFP) sensor has the advantage of high static accuracy and not affected by temperature. In large-scale projects people ofen use these two kinds of sensors integrated. But the demodulation devices in research and practical applications are directed developed at one of the sensors, existing demodulating method increases the complexing of demodulating system, decreasing dependability and enhanceing cost system. So it is necessary to study a general demodulating method for FBG and FFP sensor.The principle of FBG and FFP sensor,some methods of demodulation are introduced in the thesis. After analyzing the advantages and disadvantages of various demoudulating methods, one demodulating method that based on Fabry-Perot tunable filter is presented. The free spectral range and transmission bandwith of the filter are determined, using FFT algorithm is presented. The theoretical feasibility of the demodulating method is verified both by the theory and MATLAB simulation.According to the actual situation and specific algorithm requirement, DSP chip (TMS320VC5416) and the peripheral circuits have been designed to make hardward circuit board. The core algorithm and the control software are programmed by using C language.Separately use FBG and FFP sensor in demodulating experiment, the results show that tunable Fabry-Perot filter can be well positioned to meet the system requirements, the algorithms designed makes demodulating accuracy improved and demodulate faster.