Application Research On The Distributed Optical Fiber Temperature Measurement System Under The Freezing Method

In recent years, distributed measurement technique is one of the hot questions in the temperature measurement field which this researching task belongs to. Temperature measurement system of distributed optical fiber is paid more attention because of its strongpoint.Due to the limitation of traditional measurement system to supervise a pot, under freezing method situation to supervise all the position at the same time, it can not measure the buildings effectively. Temperature measurement system of distributed optical fiber can achieve it with ease. Design the temperature measurement system to basically satisfy the application to measure the temperature in the freezing method construction is our final goal. The relation between whole configuration and all performance of temperature measurement system of distributed optical fiber are under research.During the design the measurement system we adopted the engineering design. According to this method we can directly devise the system that can be applied in the freezing method. In this paper we will give a reliable theory or rule which designer can follow. Firstly the relative temperature sensitivity of Raman Backscattering is analyzed, the relation between Raman Backscattering signal and the function of temperature is given, different demodulation method are compared and give a method that can work efficiently. Secondly, the method of design laser driver circuit and temperature controller circuit are provide, which can let the laser work effectively in the temperature measurement system. The signal process circuit is designed in this paper, you follow this method you can complete the laser emission and the signal receive and process. At last we study the optimal demodulation method of measurement data and the calculation formula of the optimal split ratio of 1×3 coupler is given, base on this given calculation formula we can directly calculate the optimal split ratio . Following this method we retrenchment a optical filter and a magnify circuit in the system reduce the cost of the system, we also improve the stability and reliability by software engineering. Let the system can achieve videotext.At the present time, we design the temperature measurement system can measure the temperature range is -40~50℃,temperature measurement precision is 1℃,spatial resolution is 1m,optical fiber length is 2km,this can application in the freezing method. If the measurement system completeness application in the freezing engineering the temperature measurement precision will demand improve.