| The distributed optical fiber temperature sensoring (DTS) technology has caughtworldwide attention for continuous real-time measuring from its birth. DTS are not onlyequipped with premium features of general optical-fiber, but also takes advantage ofcontinuous distribution and solves some measuring tasks when other mode sensors aredifficult to be completent.DTS based on Raman back-scattering measures temperature information bytemperature sensitivity of spontaneous Raman scattering in optical fiber. Because power ofspontaneous Raman scattering is extremely weak, DTS is in essence an instrument fordetecting and processing on weak signal. As other processing systems on weak signal,algorithm problems also confront DTS, including data signal processing (DSP) algorithmon capture card and temperature demodulation algorithm. Main performance of DTSsystem depends on them, such as response time, spatial resolution, the maximum detectiondistance and so on.On the algorithm of capture card, the paper compared several algorithms used in DTSsystem, including cumulative mean, noise reduction method by wavelet, complementaryGray code method and so on. According to the specific request of fire alarm, a kind oflinear accumulation algorithm is adopted in the paper. The algorithm base on FPGAplatform is accomplished by pipeline way. Furthermore, DSP effects are compared withdifferent numbers of accumulation through the experiments.On temperature demodulation algorithms, the paper if focus on the research of thealgorithm of DTS using pumped plused Laser by Erbium Doped Fiber Amplifiers (EDFA).Experimental results indicate that theoretical temperature demodulation formula couldn’tbe applied to practice directely due to non-ideal characteristics of the system. Theinfluence and feature of amplified spontaneous emission (ASE) noise in DTS is analyzed,the modified demodulated formula using minimum value of the ASR curve is acquired by the paper and the demodulation effect would be checked in experiments. |
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