The Design And Implementation Of Optical Fiber Deformation Positioning System

With the rapid development of society,the application of large-scale infrastructure such as oil and gas pipelines,telecommunication optical cables,and electricity transmission networks has become widespread.The detection of faults at these facilities is becoming increasingly important.The detection of large-scale infrastructure often has the following requirements: larger spatial spans,high accuracy,and continuous real-time detection,so traditional detection methods cannot fully meet the needs.Distributed optical fiber sensing technology can not only detect the information distributed over a long-distance optical fiber,but also locate the information.It has the advantage that traditional detection technology cannot match,and is especially suitable for the detection of engineering facilities such as communication optical fiber.This paper taking the actual project as the background,for the demand of real-time online detection of abnormal deformation in communication optical fibers,analyzes and compares the existing Technical solutions by extensive reading of existing literature,and proposes an optical fiber deformation positioning system combining optical time domain reflection principle and interference principle to implement real-time detection and positioning of abnormal deformation such as bending,fracture,and disturbance of the optical fiber.Firstly,by analyzing the optical fiber sensing technology based on ?-OTDR and the FoxSmith optical fiber sensing technology with on 3×3 coupler,the paper proposes an improved Fox-Smith optical fiber sensor positioning technology.This technology adopts the optical path structure of the original Fox-Smith technology and improves it,which enables the system to have positioning accuracy of ?-OTDR technology and disturbance detection sensitivity of Fox-Smith technology,and solves the problems that the Fox-Smith technology cannot locate bending and fracture events and the disturbance detection sensitivity of the ?-OTDR technology is low.Secondly,according to the different signal characteristics of static events such as bending and fracture and dynamic events such as disturbances,the paper uses an accumulative averaging algorithm and a FIR filter to separately processe the two kind of signals,and proposes an positioning algorithm using a non-linear threshold curve.Combined with the characteristics of noise signal,the paper sets the nonlinear threshold curve of the algorithm according to the original detection signal,and tests the positioning accuracy.Based on the specific functional requirements of the system,this paper combines the software design,database management,network communication,embedded control system and improved optical fiber sensing technology to complete the overall scheme design of the system.The scheme is based on the design idea of functional aggregation and structure separation.The system is divided into five functional modules: optical system,control board,host computer,acquisition card and power supply module.Then,for the needs of managing laser,photodetector and power supply,the hardware circuit design and hardware program development of the control board which provides the network communication and serial communication functions are completed in combination with the embedded system.Finally,based on the overall needs of the system,software in the host computer was developed to provide the functions of querying and setting devices such as lasers and photodetectors,and implement the display,transmission,storage,and processing of test data,and then the optical fiber deformation positioning system was completed.In addition,the system is tested,which shows that the fiber deformation positioning system designed in this paper can implement the real-time detection and positioning of optical fiber deformation events,and has high positioning accuracy and sensitivity and can be widely used in fault detection of infrastructure such as communication optical fiber.