Thedesignand Implementation Of High Speed Acquisition Card Used In Distributed Fiber Optic Sensing System

The high-speed data acquisition card,based on PCI bus interface protocol,is one of the most important parts of Raman Distributed Fiber Sensing system (DOFS). High-speed acquisition card is used as signal conditioning, sampling, storing and forwarding afterphotoelectric conversion. The highefficiency and real-time of the card ensure the DOFS system to measure the temperature information accuratelyat a given resolution, and findproblems in a timely manner during applications.First of all, the paper discusses the theories of Optical Time Domain Reflectometer (OTDR), Raman optical fiber temperature sensor. Then the operation principles to improve the signal-to-noise ratio (SNR) using Golay complementary codes and cumulative average method are demonstrated. Also it introduces how both of two signal processing techniques to improve the signal-to-noise ratio, and simulations with Matlab software verify their effects. Secondly, the paper conducts a deep research to describe design principles and programs of the high-speed data acquisition card, and decided the architecture based on PCI interface and FPGA hardware circuit. Hardware circuits are desiged by Altium Designer software and divided into five sub-modules according to the technical indicators of the DOFS system. The software on FPGA part is developed by development software of Altera Corporation, and it is written with the Verilog HDL hardware description language. The bottom software realizes drivers of various hardware modules, modulation pulse of Gray complementary code and cumulative average algrithm before forwarding the acquisition data. The software on host computer, which makes use of PLX SDK Development Kit of PLX Technology Corporation, realises PCI data acquisition driver in VS2005with C++language. The high-speed data acquisition card used in DOFS system has a transmission speed from80MB/s to120MB/s, which achieves the design goal basically.