Study And Design On Signal Processing System Of Distributed Optic Fiber Temperature Sensor

The technology of distributed optic fiber sensing was brought forward in 70th's, a series of sensing mechanism and measure systems turned up and were used gradually in many fields. Nowadays, it has been one of the most promising technologies in optic fiber sensing. Distributed optical fiber sensor system can sensing the change of temperature along the optical fiber by the form of continuous function of distance. The fiber of distributed optic fiber is not only transport media but also sensing media. It has the peculiarity of insulation and resistance of electromagnetic interfere, small size and do little effect to temperature field.The back scattering Raman signal with the information of temperature is weak or completely submerged in noise. As a result, the denoising level determined the accuracy of the whole system. Weak signal measurement must be used in this system. This paper takes a deep research on the distributed optic fiber temperature sensor and resolves the following prime problems: First, the principle of distributed optic fiber temperature measuring methods has been researched and four demodulation methods have been discussed. Second, the temperature calibration method of distributed optic fiber temperature sensing system was brought forward and resolved the remaining problem. Third, a new signal processing system was designed based on the research of weak signal measurements and methods. The signal processing was the combination of software and hardware, which make full use of the system resource. Forth, a new signal processing method was discussed based on the study of distributed temperature. This method is the amalgamation of Wavelet decomposition, relevance process and average, which can raise the signal-to-noise ratio and improve the accuracy of system.