Research On Shock Wave Overpressure Detection System Based On Optical Fiber F-P Sensor And Signal Processing

As we all know,the measurement of shock wave overpressure is the main research direction.With the increase of explosive power and the deterioration of test environment,it is urgent to study the test system which can be used in more severe environment.In harsh environmental conditions,electrical sensors have certain defects,while optical fiber sensors have passivity and anti-electromagnetic interference,can effectively resist high temperature and high pressure,humidity and strong electromagnetic interference and other environmental factors.To solve this problem,this paper designed and built a test system based on fiber optic F-P sensor.The main research is as follows:Firstly,this paper compared the mainstream demodulation means such as intensity demodulation and phase demodulation of optical fiber F-P sensor.According to the characteristics of blast wave signal,this paper selected the low precision F-P cavity,and passive zero-difference demodulation method with three wavelength light source excitation and arbitrary phase interval was designed for demodulation.This paper simulated the arithmetic by Matlab software,and verified the three-wavelength phase demodulation algorithm by constructing an ideal shock wave pressure signal.Secondly,according to the test environment,this paper selected the appropriate optical devices such as light source,photodetector and coupler and passive devices,and designed the main control unit,A/D conversion circuit,FLASH memory and other system.Besides,a Zig Bee-based relay device was designed and built to realize wireless control of the test system up to 10 km away.Finally,this paper uesd the device of shock tube to calibrate the detection system of fiber optic F-P sensor.The calibration results of piezoelectric sensor and piezoresistive sensor test system are compared,which effectively verifies the practicability of the system.Meanwhile,the paper designed the Five-point cubic smoothing algorithm and Empirical Mode Decomposition(EMD)signal,which improved the test accuracy.