Research On Key Technologies Of Signal Processing In High Speed OFDR Optical Fiber Sensing System

With the advent of 5G era,Internet of things technology is becoming more and more mature.As an important part of the perception layer of Internet of things technology,sensors are widely studied and concerned.As an optical fiber sensing technology with the advantages of high spatial resolution and high sensitivity,OFDR is an important supporting technology of the Internet of Things technology.It has a wide range of applications in aerospace,large buildings,precision instruments and other fields.At present,with the theoretical and experimental research of OFDR technology becoming more and more abundant,the demand of OFDR technology for productization has been paid more and more attention by researchers.In many domestic related researches,in order to facilitate debugging and changing parameters,most of the research adopts the CPU-based software signal processing mode,but this processing method has a low speed,usually in minutes or even tens of minutes,which is difficult to meet OFDR High frequency fast measurement requirements.This paper studies the high speed of OFDR signal processing,focuses on the hardware design of the signal processing algorithm of OFDR technology,and uses the FPGA development platform to implement hardware parallel acceleration of the key algorithm of OFDR signal processing.Design and construction of high-speed OFDR parametric sensing system.The main contents of this paper are as follows:1.Based on the basic principle of OFDR technology,we analyzed the nonlinear tuning effect of tunable light source,and proposed a suitable solution according to the high-speed characteristics of the system.At the same time,we studied the influence of the parameters of the light source on the parameters of the sensor systemand designed the reasonable sweep parameters and modes of the light source2.In order to meet the requirement of high-speed OFDR signal processing system,the key algorithms of OFDR signal processing algorithm,we analyzed large-scale FFT algorithm and cross-correlation algorithmtheoretically.In FPGA hardware environment,the algorithm is designed and resources are pre evaluated,which makes the realization of logic fully parallel.According to the pre evaluation results of the algorithm,we completed the selection of FPGA hardware platform and the development and debugging of the key algorithms of signal processing on the hardware platform 3.We designed the overall system of high-speed OFDR optical fiber sensor is designed,and the auxiliary interferometer is built as the external clock sampling to eliminate the nonlinear tuning effect of the light source.According to the characteristics of high-speed system,the analysis and selection of key devices are completed,and the main instrument is built to generate the back Rayleigh scattering signal.According to the principle of external clock sampling,a high-speed signal acquisition system is designed and built.The overall construction of the high-speed OFDR sensing system is completed.The sensing distance of the system can reach 50m,the local spatial resolution can reach 5mm,and the sensing time at a sensing distance of 5m is less than 50ms.And through the strain parameter sensing to verify the feasibility of the system and various parameters.