Research On Optical Fiber Temperature Sensor Based On Raman Scattering

Distributed optical fiber temperature technology could measure the temperature field where fiber locates,which uses after-reflection of Raman scattering light.It has the characteristics of small volume,good anti-jamming and precision,and is widely used in biomedical,industrial processes,national defenseand so on.We made overall system design of the distributed optical fiber temperature sensor system,and the main work is as follows:(1)Make a deep research on Raman scattering theory and mainly analysis two demodulation algorithm: single channel demodulation algorithm and dual channel demodulation algorithm.By compared both of them,adopted dual channel demodulation algorithm for the system,and make some data sampling experiments.(2)Select some key components,eg: processor,AD.This system break the PC+ FPGA mode,adopted FPGA+DSP+ARM mode.On the one hand,PC+FPGA mode has the characteristics of simple module,easy development,but the power consumption and volume is larger;On the other hand,FPGA+DSP+ARM mode makes full use of the advantages of each processor: FPGA has the characteristics of hardware editable properties,and is suitable for high speed logic operation;DSP is suitable for mathematical operation;ARM is suitable for interface design,which makes the whole system low consumption,high speed and small volume.Single channel AD could reduce the design cost by using time-sharing multiplexing way.(3)Design a kind of new and high speed PCB for system,including anolog circuit and circuit of AD and overall design of PCB,and mainly consider the the integrity of the key signal in the sampling process,such as analog signals,high-speed signal,which could provides a good guarantee for Raman signal acquisition.(4)Design softeware for system.On the platform of FPGA,design a high-speed accumulator by verilog,which improves the signal-to-noise ratio of the Raman signal;On the platform of DSP,completed temperature demodulation algorithm on SYS/BIOS and synchronous control of DSP and FPGA;On the platform of ARM,make full use of relative mature embedded technology,realize the SQL database,human-computer interaction interface of QT and dual-core communication based on syslink.