Research Of Signal Processing Method In Distributed Fiber Temperature-measured System

Distributed optical fiber temperature sensing technology has been proposed in1970s,this technology has been widely applied in various fields with many years development and research.As a branch of distributed optical fiber sensing technology,it has been one of the most promising in optical fiber sensing technologies especially.This paper expounds the general structure of the system by analysising each part of the device performance parameters and selection,based on the analysis and research Raman distributed optical fiber temperature sensor measuring principle.The measuring temperature principle of distributed optical fiber temperature sensor is the spontaneous Raman back scattering temperature effect and OTDR technology.The multi-point measurement of temperature can be achived by conducting spatial orientation of temperature field with OTDR technology.The fiber is not only transport media but also sensing media.Compared to the traditional temperature measurement system,the security and stability are incomparable.Therefore,distributed optical fiber temperature sensor can be widely used in the following occasions,such as the temperature measurement in coal mine; disaster prevention and warning system of the tunnel;the hot spot monitoring and control of underground and power cable;the distribution measurement,thermal protection and fault diagnosis of all kinds of large and medium-sized transformer and generating set.Data acquisition system is an important component of modern information processing system, which is widely used in communications, telemetry and remote sensing. Because data collection is often accompanied by noise, so the data acquisition system needs to filter the collected signal to improve the accuracy of collected data. With the development of society, it is more and more important for a data acquisition system with more data, higher processing rata and better real-time. Accumulating treatment after multiple data collection is tradition way to eliminate noise, but it would take a lot of storage resources and cause larger processing time. This method has become more difficult to meet the actual demand.In compare with the tradition data acquisition and filter model, the paper designed a high-speed data accumulator and filter which is based on FPGA (field programmable gate array) to deal with the collected signal. The whole system based on FPGA is designed using Cyclone Ⅱ EP2C5F256C6chips of ALTER company,the design relaized some function modules,such as addition module,double port RAM module and some auxiliary signal control module.FPGA devices have the features of high reliability, rich resources, high-speed and parallel computing capacity. This system uses FPGA as the core CPU. The design completed the pipeline processing of accumulating and storing. The design uses Verilog HDL language in each module and uses QUARTUS Ⅱ sofiware to design. The experiment test shows that the method is stable, occupy less system resourses and has fast processing speed.In this research,cumulative average filtering method is used to reduce noise and improve signal-to-noise ratio.And sophisticated analysis software programming is avoided combining with MATLAB which has a powerful data processing ability,so computer resources is made a full use and the system is speed up.In otherwise,this method can facilitate the application and maintenance of the test system.It also meet the requirement of the actual distributed temperature measuing system and monitoring environment.