Research On Distributed Optical Fiber Temperature Measurement System And Temperature Drift

With the rapid development of China's economy in recent years,and there is a rapid development of infrastructure construction.A large number of highway tunnels,railway tunnels,substations,underground cables,urban rail transit,hydropower dams and other infrastructure projects are increasing.The use of distributed fiber temperature measurement system demand is also greatly increased.It has a real-time online monitoring of all fiber temperature points,a large range measurement of non-live work and other advantages are widely used,and the development prospects are good.Distributed optical fiber temperature measurement system is complex,vulnerable to the external environment.There are many parts of the internal temperature sensitive changes.The system signal is a small signal,and the noise interference is more serious.Therefore,this paper mainly studies the system noise reduction,compensation system temperature drift and research system of light source and photoelectric conversion module affected by temperature.The main contents of this paper are as follows:(1)This paper analyzes the development status of distributed optical fiber temperature measurement system at home and abroad,discusses the advantages of distributed optical fiber temperature measurement technology,and finds out the lack of filter technology and temperature drift control,and leads the research content of this subject.The process of Raman scattering is studied in depth,and the reason of the different Raman scattering intensity is explained by the angle of quantum mechanics.By analyzing the temperature demodulation method,choose to use dual anti-stocks and stocks demodulation.The principle of OTDR and the principle of temperature calibration are discussed.(2)System design and analysis.The design of a distributed optical fiber temperature measurement system,introduced the system structure design,part of the circuit design,hardware components and device selection,the system uses Raman scattered light for temperature demodulation.The influence of temperature on the three parts of the light source module,photoelectric conversion module and sensor fiber is discussed,and the elimination measures are discussed.(3)Research on System Filtering Method.The advantages and disadvantages of smoothing filter,digital cumulative filtering and wavelet filtering are compared in detail,and the filtering method is experimented.Finally,the filtering results are compared with the three filters,and the optimal filtering effect is achieved.On the basis of combinatorial filtering,the main performance indexes of the system are determined by experimental method.(4)System Temperature Compensation and Temperature Drift Research.Based on the experimental results,the temperature drift law of the system is found out,and the temperature compensation formula is used in the system.And verify the feasibility of the compensation method.The relationship between the output voltage,the reverse voltage and the temperature of the APD is studied by studying the relationship between the temperature,current,output wavelength and output power of the laser.The causes of the system temperature drift are given and the relevant solutions are given.To improve the APD bias control and laser control program premise.