An Enhanced Multiple Intrusion Event Localization Algorithm Based on Dual MZ–Sagnac Optical Fiber Sensing Perimeter Security System

Interferometric distributed optical fiber vibration sensing technology has been widely applied in the field of perimeter security. Among various structures, the dual MZ–Sagnac optical fiber sensing perimeter security system (the dual MZ–Sagnac system) plays an important role in perimeter security due to its high sensitivity, electromagnetic resistance, corrosion resistance, high stability and low cost. However, under the condition of low-SNR signals, the traditional event localization method for the dual MZ–Sagnac system, which directly averages the localization results of continuous short-interval signals, leads to great errors. In this paper, by employing the Cram´er-Rao Lower Bound (CRLB) theory of cross-correlation time delay estimation method, a Weighted Gaussian Superposition (WGS) algorithm based on the dual MZ–Sagnac system is proposed to enhance event localization accuracy and distinguish multiple vibration events. Vibration signals are collected and CRLB conformity to the dual MZ–Sagnac system is validated. Furthermore, the WGS algorithm reveals a minimum MSE of 1.63, corresponding to the error of 1.28 m and an accuracy improvement of 72 % in the experiment. Additionally, an application is performed to evaluate the effectiveness of the WGS algorithm for multiple events discrimination and localization. In perimeter security scenarios utilizing the dual MZ-Sagnac system, the WGS algorithm not only further refines the localization precision but also enables the system with multiple events discrimination, allowing the measurement instrumentation to better adapt to engineering applications.