Research Of Distributed Optical Fiber Temperature Measurement System Based On Virtual Instrument Technology

Distributed optical fiber temperature sensing technology has been proposed in 1970s, with many years development and research, this technology has been widely applied in various fields. Fiber optic distributed temperature sensing, a branch of distributed optical fiber sensing technology, is one of the most promising in optical fiber sensing technologies especially.The distributed optical fiber temperature sensor can monitor many points' temperature along a single optical fiber simultaneity, and the position of temperature field can be located with OTDR technology. In other words, the sensor can measure the temperature field easily, the fiber is not only transport media but also sensing media. Compared with conventional temperature measuring system, distributed optical fiber temperature sensor system has an advantage in signal security and stability. In view of these unique advantages, distributed optical temperature sensor can be used in flammable and explosive occasions such as the temperature measurement in coal mine; disaster prevention and warning system of the tunnel; in the underground and hot spot monitoring and controlling of the overhead high-voltage power cables; distributed temperature measurement, thermal protection, fault diagnosis of varieties medium and large transforms, generator and so on.This dissertation uses LabVIEW 8.2 workbench developed by American National Instrument corporation, with the workbench the temperature signal which is gathered by the sensor can be de-noised, combining with time-domain accumulated average and wavelet multi-resolution analysis methods the useful temperature signal is extracted and the ration of signal to noise(SNR) is improved effectively. Based on the analysis and research on the Raman distributed optical temperature sensor principle, the performance parameters and choice of some system devices can be found, and the overall composition of the system is also described.In this dissertation, the hardware circuit of the system is designed, and the displaying and gathering of the temperature field signal is achieved, also the method which combines the wavelet multi-resolution analysis and time-domain average accumulated algorithm in the LabVIEW development workbench is also completed. With these two algorithms combination, the gathering temperature signal mingled with noise can be de-noised. In this dissertation,the traditional spectrum analysis instruments, oscilloscopes and other equipments is abandoned, but the functions of the traditional instruments is achieved with virtual instrument technology, and sophisticated analysis software programming is avoided combining with MATLAB which has powerful data processing capability,the system's data processing capability can be enhanced with this method, computer resources is made a full use and also speed up the system. In otherwise, this method can facilitate the application and maintenance of the test system, it also meet the requirement of the actual distributed temperature measuring system and monitoring environment.This dissertation focus on de-noising signal in the LabVIEW workbench, and data storage and display in LabVIEW development platform is also completed, real time of the system can be improved effectively.Figure[30] Table[1] Reference[79]...