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Distributed fiber optic intrusion sensor system for monitoring long perimeters

机译:分布式光纤入侵传感器系统,用于监视长距离

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The use of an optical fiber as a distributed sensor for detecting and locating intruders over long perimeters ( > 10 km) is described. Phase changes resulting from either the pressure of the intruder on the ground immediately above the buried fiber or from seismic disturbances in the vicinity are sensed by a phase-sensitive optical time-domain reflectometer (φ-OTDR). Light pulses from a cw laser operating in a single longitudinal mode and with low (MHz/min range) frequency drift are injected into one end of the single mode fiber, and the backscattered light is monitored with a photodetector. In laboratory tests with 12 km of fiber on reels, the effects of localized phase perturbations induced by a piezoelectric fiber stretcher on φ-OTDR traces were characterized. In field tests in which the sensing element is a single mode fiber in a 3-mm diameter cable buried in a 20-46 cm deep, 10 cm wide trench in clay soil, detection of intruders on foot up to 4.6 m from the cable line was achieved. In desert terrain field tests in which the sensing fiber is in a 4.5-mm diameter cable buried in a 30 cm deep, 75 cm wide trench filled with loose sand, high sensitivity and consistent detection of intruders on foot and of vehicles traveling down a road near the cable line was realized over a cable length of 8.5 km and a total fiber path of 19 km. Based on these results, this technology may be regarded as a candidate for providing low-cost perimeter security for nuclear power plants, electrical power distribution centers, storage facilities for fuel and volatile chemicals, communication hubs, airports, government offices, military bases, embassies, and national borders.
机译:描述了使用光纤作为分布式传感器来检测和定位长距离(> 10 km)上的入侵者。相位敏感的光学时域反射仪(φ-OTDR)可以检测到入侵者在埋入的光纤正上方的地面上的压力或附近的地震干扰引起的相变。来自以单纵模工作并且具有低(MHz / min范围)频率漂移的连续激光器的光脉冲被注入到单模光纤的一端,并用光电探测器监视反向散射的光。在卷轴上使用12 km光纤的实验室测试中,表征了由压电光纤拉伸器引起的局部相位扰动对φ-OTDR迹线的影响。在现场测试中,传感元件是一根单模光纤,直径3毫米,埋在粘土中20-46厘米深,10厘米宽的沟槽中,直径3毫米,检测距离电缆线4.6 m处的入侵者已实现。在沙漠地形野外测试中,传感光纤位于直径4.5毫米的电缆中,该电缆埋在30厘米深,75厘米宽的沟槽中,该沟槽中充满了松散的沙子,具有高灵敏度,并且能够连续检测到脚上的入侵者和行进中的车辆在8.5 km的电缆长度和19 km的总光纤路径上实现了靠近电缆线的距离。根据这些结果,可以认为该技术是为核电站,配电中心,燃料和挥发性化学物质的存储设施,通信中心,机场,政府机关,军事基地,使馆提供低成本外围安全保护的候选方法。和国界。

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