多点扰动对光纤分布式扰动传感器定位准确度的影响

Effects of Multiple Disturbances on the Location Precision of Fiber-Optic Distributed Disturbance Sensor

基于激光干涉原理,建立了基于Mach-Zehnder干涉仪的光纤分布式扰动传感器多点同时扰动的信号模型.在此基础上,通过数值模拟研究了多点同时扰动对传感器定位准确度的影响,明确了多个扰动信号同时作用时扰动的幅值比和位置差不同情况下传感器的定位准确度.仿真结果表明:当多点同时扰动的信号幅度差别大于等于20倍时,可以给出较强扰动的定位信息;当多点同时扰动的空间距离小于等于100m时,可以近似看成单点扰动.在光路中增加偏振分束器来抑制偏振衰落的影响,并采用信号发生器对实验光路中的两个压电换能器同时施加正弦信号来模拟扰动进行实验.实验结果表明:在5km和10km的位置同时施加扰动,当两个扰动的幅值比大于等于20时,距离较强扰动点的最大定位误差的最大值为200m;在5km和5.05km位置同时施加幅值比为1的扰动,距离5km位置的最大定位误差为200m,验证了仿真结果的正确性.该研究为多点同时扰动条件下光纤分布式扰动传感器定位准确度的提高和误报率的降低提供了理论指导.

The mathematic models of the Mach-Zehnder interferometers based fiber-optic distributed disturbance sensor for the multiple disturbances applications were established in accordance with coherent lightwave theory. According to the models, the influences of the multiple disturbances on the location precision of the fiber-optic distributed disturbance sensor were simulated. The relationship concerning the location precision, the amplitude ratio and the distance of the disturbances were presented. The simulation results demonstrate that the stronger disturbance can be located when the amplitude ratio of the multiple disturbances is larger than or equals to 20. The multiple disturbances can be regarded as a disturbance when the distances of the disturbances are less than 100 m. The polarization beam splitters were utilized to eliminate the influence of the polarization induced fading. Then the signal generator produced sine wave, applied to the two piezoelectric transducers simultaneously to simulate the disturbances. The experimental results show that when the amplitude ratio of the two disturbances imposed on the sensing fiber at 5 km and 10 km is larger than or equals to 20, the maximum location error from the strongest disturbance is 200 m. The maximum location error from the 5 km position is 100 m when the amplitude ratio of the two disturbances applied at 5 km and 5.05 km is 1. The numerical simulation results were proved by the experiments and helpful to improve the location precision and reduce the false alarm rate for multiple disturbances applications.