Design Of High-Speed Data Acquisition System For Botda Distributed Optical Fiber Sensor

BOTDA distributed optical fiber sensors has the advantages of long sensing distance,high measurement accuracy,simultaneous measurement of temperature and strain,etc.It has important application prospects in safety monitoring and accident warning of large buildings,oil pipelines,communication systems and power systems,which makes it a hot topic at home and abroad currently.However,due to limitations of related devices and technologies,BOTDA distributed optical fiber sensing technology can not fully meet the needs of practical projects.For example,detection and acquisition of high-speed Brillouin scattering signals is one of the key technologies that needs urgent solution.Therefore,this paper designs a high-speed data acquisition system based on the actual needs of BOTDA distributed sensors.In this paper,the performance parameters of the high-speed data acquisition system are determined according to the performance indicators of the BOTDA system,and a design scheme is proposed with the architecture of ADC+FPGA+USB3.0 to realize the detection,acquisition,and processing of high-speed Brillouin scattering signals.In order to realize the detection of high-speed Brillouin scattering signals,a photoelectric detection module was designed,including a photoelectric conversion circuit,a balanced amplification circuit,and an R-2R network programmable attenuation circuit.It can not only detect continuous light,but also detect pulsed light and automatically adjust the output voltage;In order to meet the requirements of long-distance high-resolution BOTDA systems,a high-speed data acquisition module was designed,including high-speed A/D module,FPGA module,USB module and PCB board,which realized the collection and processing of high-speed Brillouin scattering signals,and the sampling rate was 500 MSPS,which was small and easy to use.In order to achieve the extraction of weak Brillouin scattering signals,FPGA-based digital BOXCAR integrator was designed,including BOXCAR integration module program,synchronization control module program and data storage module program.This method of using hardware to implement BOXCAR integration had the characteristics of high processing speed.The designed high-speed data acquisition system has been applied to BOTDA distributed fiber optic temperature sensors and completed preliminary experiments.