Study On Optical Fiber EFPI Sensors Demodulation System Based On DSP

Compared with the traditional electric sensor, the optical fiber sensor has somecharacteristics:high sensitivity; anti-electric magnetic field interference; generating noelectromagnetic interference; safety, it can be used in some place with danger and strongelectromagnetic interference; an integration sensing and transmission; the multiplexing anddistribution measurement of sensor can be achieved. The optical fiber EFPI sensor is apioneer in actual projects and has been widely used in strain test of intelligent structure andlarge structural health monitoring.A digital signal processing chip based portable demodulation system for themeasurement of optical fiber Extrinsic Fabry-Perot Interferometric sensors is demonstrated.In order to satisfy the requirements of high-speed and high-precision demodulationapplications, a method which measures the transmission wavelength of the EFPI isproposed. By using a DSP, the reflected optical spectrum of an EFPI can be tracked, and thetransmission wavelength can be calculated. Based on a calibration method, the measurandcan be interrogated. The results of the experiment show that a wavelength resolution of2pm can be reached and the dynamic measurement range is as high as50nm.The main content of this paper is as follows:The first chapter shows us several common optical fiber sensors. By the contrast, theadvantages of the EFPI sensor are demonstrated. Further more, it describes the researchstatus of EFPI sensor demodulator. Finally, it states the development process of white-lightinterference measuring technique and gives a summary to the this topic research content.The second chapter introduces the fundamentals and demodulation method of theEFPI sensor.The third chapter puts forward a whole design project and gives a brief introduction ofmain modules of the demodulator: sensor signal collecting modules, data processingmodules and D/A modules.The forth chapter explains its data processing modules—DSP, presents thecharacteristics and model selection of DSP, and finally presents the TMS320F28335whichis used in the topic.The fifth chapter designs the algorithm of EFPI sensor demodulator, including thesignal collecting, derivation and wave filtering etc. which help to get the final sensortransmission wavelength.