Research On Accelerating The Computation Of Φ-OTDR Sensing System Based On FPGA

Distributed optical fiber sensing system is a sensing system that is widely studied and applied at present,and it has an irreplaceable advantage compared to the traditional sensing system.The distributed optical fiber sensing system uses passive optical fiber as the sensitive component,which has the advantage of anti-electromagnetic interference,anti-deformation and high sensitivity.At the same time,it can realize long-distance multi-point multi-physical quantities(vibration,strain,temperature,etc.)detection on a single fiber.Phase-sensitive optical time domain reflectometer(Φ-OTDR)is a distributed optical fiber sensing system,it can implement quantitative detection of external physical quantities,and meet the testing requirements in the fields of security,transportation,construction,etc.With the researcher delve more deeply into the research of Φ-OTDR system,the detection performance(sensing distance,accuracy,response speed,etc.)of Φ-OTDR system is gradually improved,the amount of data for signal process is increasing continuously,how to realize real-time processing and transmission of large amount of data has become one of the bottlenecks that the technology needs to solve.This subject has carried out related research on the performance problems faced by the high performance Φ-OTDR system.The main research contents of this subject as follows:1.The subject has performed a theoretical analysis of the Φ-OTDR system and determined the signal processing flow of the system,analyzed the performance bottlenecks in the signal processing flow,proposed the use of FPGA to accelerate the Φ-OTDR signal processing,and calculated the data bandwidth.2.The subject has designed a FPGA-based Φ-OTDR signal processing platform,the hardware use Artix-7 FPGA as the signal processor,and use high-speed ADC,DDR3 memory and PCIe interface;which is designed by circuit design software,and made a prototype.3.The subject developed an Φ-OTDR signal processing program using Verilog on FPGA.The program uses a pipeline processing architecture,and uses a series of accelerated computation algorithms such as sliding window data frame segmentation,parallel FFT calculation,and multi-level buffer.This project realized the real-time processing of Φ-OTDR signal under 40 KM sensing distance and 2 KHz repetition frequency.4.The subject developed a set of upper computer program on the industrial personal computer to realize real-time display and storage of calculation results,and show the external vibration intensity and position information in real time.After testing,the FPGA based digital signal processing accelerator can greatly relieved the pressure of data processing use traditional computer.The system can ensure the real-time operation of Φ-OTDR sensing system at high repetition frequency,and guaranteed the reliability and stability of the system.