利用高相干、低噪音激光器作为光源,设计了2干涉臂长度差为60 m的长光程差光纤迈克耳孙干涉仪作为传感器。采用二元矩形脉冲对光源进行相位调制,结合正交信号解调法恢复相位信息,由基于现场可编程门阵列(FPGA)的高性能询问器实时实现相位信号的计算。结合时域穿越统计(LC)报警算法,提高了对入侵事件报警的实时性及精确性。最终搭建了包含4个防区的安防系统,该系统询问设备简单、成本低、实时性高。实验结果表明,通过设定合适的阈值,系统可以对各种入侵和干扰行为实时进行报警,同时对雨雪等恶劣环境的误报进行有效抑制,该系统持续工作1个月,未出现漏报,误报率低于1%。

We use highly coherent and very low-noise laser as the light source to design fiber Michelson interferometers with an optical path difference of 60 m used as the front-end transducers. Binary rectangular pulse is used to modulate the phases of the light source, and the phase signals are restored with an orthogonal demodulation algorithm. A highly efficient interrogator controller based on field programmable gate array(FPGA) is used to calculate phase signals in real time. Real time and accuracy of invasion alarm signals are improved, based on the time-domain level crossing (LC) algorithm. Finally, a four-zone security system is set up, which has advantages of simple interrogator controller, low cost and real-time handling capability. The experimental results show that the system can alert all kinds of intrusions in real time and suppress the false alarm caused by the environmental noises, such as winds and rains, under the chosen proper threshold. The system has worked for 1 month without alarm failure and the false alarm rate is less than 1%.