干涉型光纤预警系统入侵信号的调制解调技术

Research on Modulation and Demodulation of Intrusion Signal Based on Interferometric Optical-Fiber Early-Warning System

为解决干涉型光纤预警系统因偏振退化而出现的误报漏报以及定位失准的问题,在建立Mach Zehnder干涉系统结构模型的基础上,通过分析入侵信号的调制过程,得到两种调制信号失真现象,并详细推导了该问题的解决方案:基于耦合器的解调算法。为使该方案满足工程应用要求,提出一种参数调校方法消除实际耦合器不均衡引起的解调结果失真,并在Simulink环境下进行仿真分析。结果表明,该解调算法能在耦合器不均衡、出现偏振退化与待解调信号含有高次谐波的条件下准确还原相位信号,对系统工程应用具有指导性意义。

In order to reduce the false alert or missed alert which is caused by polarization degradation of interferometric optical-fiber early-warning system,the modulation process of intrusion signal is analyzed based on the structure model of Mach Zehnder interferometric system.Two kinds of modulation signal distortion are studied,and the solution,3×3 coupler demodulation method is derived in detail.To meet the demand of engineering application,a parameter correction method which can corrected demodulation distortion due to unbalanced coupler is put forward.Simulation result in Simulink showed that the demodulation method can restore phase signal accurately while the 3×3 coupler is unbalanced or polarization degradation occurred or the signal contains high order harmonics and it is useful for engineering application of this system.