Study On Demodulation System For Fiber Grating Based On STM32Technology

FBG sensor is the hot spots for the investigation in the field of fiber optical sensors in these years.It has many advantages such as:it is easily re-useable,protect against EMI, high insulation performance,good anti-explosion and corrosion resistance, with the development of the Fiber Optical Communication Technology,it is widely used in the safeguards for the huge buildings such as bridge,dam. And the portable FBG interrogator is a kind of measuring instrument adopted embedded microprocessor,high performance data collection, processing etc which is consist of the hardware and software, and it is small size,light weight,low cost,high reliability, advanced functions.in addition,it is much convenient for using,thus it posses higher market value and use value.At resent, the demodulation method of the FBG sensor mainly includes spectrograph method, Interferometry, Wavelength tunable laser method, the FBG grating dispersion demodulation method, filter method, etc. in of them, tunable F-P filtering method has the advantages of high sensitivity,long tuning range etc.so this article have had an in-depth study on the demodulation method of tunable F-P filtering method.The main content of this article is about the study how to demodulate the signal’s physical quantity detected by the FBG. The core device of demodulating system in this article is fabry-perot (F-P) filter, it analysis the working principle and characteristic parameter,as well as has a discussion on the special relationship between the scanning-driving voltage of the filter and central wavelength while using the relations between them,and establish the digital relationship model between the driving voltage and being tested physical signals.For the part of hardware,it adopts the STM32F103VCT6microcontroller based on the inner core ARM Cortex-M3. During the process of acquisition by driving voltage, it designs the photoelectric conversion of the sensing signal and signal amplification etc, transmitting the sensing signal into the STM32F103VCT6microcontroller and have the processing for AD transition and LCD display transition,finally acquire the signal demodulation result.We have the temperature sensing experiment on The fiber Bragg grating demodulation system which is based on the F-P filter, fitting experiment data with the MATLAB tested and verified the feasibility of the demodulation system.