Improved Vibration Localization Algorithm for Multiple Intrusions Based on Phase Spectrum Estimation in Distributed Mach–Zender/Sagnac Optical Fiber Sensing System

Interferometric distributed optical fiber sensing technology has emerged as an important branch in the field of optical fiber sensors, and the research on the technology is of great significance. In this article, a distributed optical fiber vibration sensing localization algorithm based on phase spectrum time delay estimation is proposed. The algorithm effectively overcomes the limitations in stationary periodic vibration signals localization and multiple vibration signals localization. Theoretical analysis is presented to clarify the principle of vibration localization, especially for multiple vibrations localization. The experimental verification of vibration signal localization on a 40-km optical fiber is demonstrated. The experimental results show that the localization error is less than 20 m for the single-point stationary periodic vibration signals, while less than 50 m for the instantaneous vibration signals. This algorithm achieves the simultaneous localization of multiple stationary periodic vibration signals, while also enabling the concurrent localization of both stationary periodic signals and instantaneous signals. The algorithm shows the capability of multiple vibration signals localization.