Research On The Application Of Distributed Tunnel Temperature Measurement Systems Based On Optical Fibers

Optical fibers rencently have become important elements in communication network systems and sensing systems due to their high efficiency of light transport and their large bandwidth.They are not only used as sensitive elements of sensing systems,but also as transmission media of sensing systems to transport sensing signal. These properties have made fiber optics increasingly important in light analysis and in remote sensing.The distributed optical fiber sensing is a subject direction of develop- ment and many sensing schemes have been developed to measure a number of physical parameters. Distributed optical fiber temperature measurement system have been widely used in the temperature monitoring and alarm applications,due to distributed measurement of temperature and position point along long optical fiber.With rapid development of various types of traffic tunnels, heavy casualties and economic losses caused by overseas tunnel fire give us a warning.So this paper picks up distributed temperature measurement systems to monitor the temperature of tunnels.This paper introduces the research status and development trend of distributed optical fiber temperature sensing technology,also analyses the advantage of temperature measurement.Then this paper introduces the two development of Raman distributed temperature optical fiber sensing technology,we select the ROFDR to have a research.In the last we also research the temperature measurement principle of ROFDR and introduce the function of each part in the ROFDR.Various distributed optical fiber temperature measurement principle is analyzed and studied in this paper. Through the fiber properties, fiber optical transmission and the description of scattering phenomena,this paper introduces three types of distributed fiber optic temperature sensing technology and initially proposed the concept of optical frequency domain reflectometry(OFDR).This paper researches deeply thesis on Raman distributed optical fiber temperature measurement based on OFDR and propose the system architecture.After introducing the system operation procedure,the article haves a more details on devices selection in each module and design of hardware circuits. photoelectric conversion module, signal source modules, signal sampling and processing module are included in the system. System uses ADL5317 to control APD’s bias voltage in photoelectric conversion module, signal source modules use AD9951 and ADC is ADS8364. The system uses DSP as the controlling and signal processing component, and this may improve the system performance.This article haves do more research on Raman scattering,then study the Stokes and anti- Stokes in OFDR.Paper also uses the frequency domain transfer function and impulse response function to do research on Stokes and anti-Stokes signal processing.,and simulates to the system of ROFDR, the simulation results prove that the approach of distributed temperature measurement is right. The system performance is also analyzed. Finally this paper design the the system software of main function modules.