Design And Fabrication Of Optical Time Domain Reflectometer Based On FPGA

Fiber optic communications are very widely used in modern communication systems because of its brand bandwidth, anti-interference ability, low attenuation and many other advantages. Optical time domain reflectometer(OTDR) is an important test instrument, which can measure the actual length, average loss, and can detect, locate and measure any location on the fiber link events in optical fiber communication system. OTDR is widely used in engineering installation, maintenance and monitoring of online communications network in optical fiber communication, which has important research significance.The paper uses a high performance FPGA to complete the design of the optical time domain reflectometer. Firstly this paper briefly introduces the OTDR development history and research status at home and abroad, put forward the thesis’s focus and innovation points. After analyzing the basic theory of OTDR, the paper then proposes the structure of the system. FPGA controls the light emitting module to produce light pulses through an optical circulator in optical fiber transmission, as the fiber present in the Fresnel and Rayleigh scattering, the reflected optical signal from the optical receiving module converted into electrical signal, then filtered, amplified to AD convertor. FPGA collect signals from AD, then storage and process, and upload to the host computer by usb to do further analysis and processing. Based on the structure of the system, the paper introduces the working principle of each module and its software and hardware implementation scheme in detail. The whole system works as a virtual instrument which PC software controls FPGA to achieve the function of OTDR design.The software and hardware of the design is compact and reasonable, at the same time this OTDR has good performance, high stability, and the resolution and dynamic range has reached predetermined target.