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基于多波干涉原理,建立了基于相位敏感光时域反射计(OTDR)的光纤分布式扰动传感器(FDDS)光路系统数学模型,研究了激光器频率漂移对相位敏感OTDR定位精度的影响机理。仿真结果表明:激光器的频率漂移是导致传感器定位精度和信噪比降低的关键因素,当激光器的频率漂移分别高于25 MHz/min和30 MHz/min时,依据移动平均和有扰动减无扰动定位方法以及移动平均和移动差分算法得到的传感器信噪比低于2dB,定位算法失效。采用频率漂移速率分别为3MHz/min和190 MHz/min的激光器进行实验,实验结果表明:频率漂移速率为3MHz/min的激光器通过所述的两种定位方法得到的定位误差均为100m;频率漂移速率为190MHz/min的激光器无法实现扰动的定位。研究结论为激光器的选型以及提高传感器的定位精度提供了理论指导。
Based on the principle of multi-wave interference, a mathematic model of optical fiber distributed disturbance sensor (FDDS) optical system based on phase sensitive optical time domain reflectometer (OTDR) is established. The influence mechanism of laser frequency drift on the positioning accuracy of phase sensitive OTDR is studied. The simulation results show that the frequency drift of the laser is the key factor to reduce the positioning accuracy and signal-to-noise ratio of the laser. When the laser frequency drift is higher than 25 MHz / min and 30 MHz / min, respectively, Positioning method and the moving average and moving differential algorithm to obtain the sensor signal to noise ratio is less than 2dB, positioning algorithm failure. The experimental results show that the lasers with 3MHz / min frequency drift rate get 100m positioning error by 100m respectively. The frequency drift The 190 MHz / min laser can not position the disturbance. The conclusions of the study provide theoretical guidance for the selection of laser and the improvement of the positioning accuracy of the sensor.