Design And Optimization Of Distributed Optical Fiber Temperature Measurement System Based On Raman Scattering

DTS is a temperature measurement system based on the relationship between the power of scattered light in the sensing optical fiber and the temperature. The temperature measurement method overcomed the shortcomings of the traditional methods of measuring temperature, it has unique advantages.For example it is not affected by electromagnetic interference, it has good insulation,light quality and small size, it can be used for long distance temperature measuring and can use on many applications. DTS is not subject to electromagnetic interference, which can be used to monitor the temperature along the cable. It is suitable for long distance temperature monitoring, such as gas pipeline, tunnel and so on. With the increase of distance the cost performance is higher than other system. In addition, the distributed optical fiber temperature measurement system has a simple line layout,and temperature distribution long the sensing fiber can be read directly through the temperature measuring software,which can reducing the workload of installing the temperature measurement system.In foreign countries, the research of distributed DTS began in the 70s of the 20th century, China began to research in the 80s of the 20th century.Now, the DTS technology continues to developing,and system performance is continuously being optimized, it will be used in more place.This article explains the temperature measuring principle and positioning principle of DTS based on Raman scattering.Other DTS principle is also being introduced including principle of temperature measurement based on Brillouin scattering. Principle of DTS based on Rayleigh scattering and principle of fiber Bragg grating temperature measurement also be introduced.And all kinds of principle are compared with each other.This paper introduces the hardware system, which including the laser, WDM, avalanche diode (ADP). data acquisition card and sensing optical fiber. The performance requirements of each component and the selection criteria are described, the process of converting anti-Stokes and Stokes scattering light signal into temperature signal is expounded in this paper.The system performance including temperature precision, resolution of position, location accuracy and responsed time are analyzed in the paper. After measureing the system performance, this paper proposes a method of piecewise linear fitting to improve measurement precision,and adding light switch components to increase the system temperature measurment range, using the algorithm to realize the function of fire early warning.Improving the performance of the system in many aspects.Finally the paper analyses the building fire alarm experimented discussed whether the fire warning function is available to detecte building fire.Two kinds of early warning methods are compared, and the application occasions of the two kinds of methods and the requirements of the fiber layout are obtained.