Intrusion detection and location method of distributed fiber optic fence based on φ-otdr

Abstract

The invention discloses a distributed optical fiber fence intrusion detection and location method based on a phi-OTDR (Optical Time Domain Reflectometer), and the method comprises the following steps of: firstly, subtracting an acquired ith signal by an acquired (i-1)th signal to obtain a preprocessing monitoring signal; secondly, carrying out at least four-layer wavelet decomposition on the preprocessing monitoring signal by adopting a plurality of wavelet functions; thirdly, judging whether actual intrusion exists according to the consistency of distribution positions of maximum-wavelet mode maximums in all scale signals; fourthly, judging that the actual intrusion exists if the distribution positions of the maximum-wavelet mode maximums in at least three scale signals are consistent; fifthly, corresponding multiplying the scale signals in which the intrusion exists and the distribution positions of the maximum-wavelet mode maximums are consistent to obtain a composite signal of which pseudo maximums are inhibited and mode maximums at a catastrophe point are enhanced, using a position corresponding to the maximum-mode maximum in the composite signal as a position of the determined intrusion point, determining the intrusion generation and the intrusion position by combining various composite signal judgment results of wavelet multi-scale analysis according to the majority voting criterion.

Description

technical field [0001] The invention relates to the field of perimeter security and distributed optical fiber sensing signal processing, in particular to a method for intrusion detection and positioning of distributed optical fiber fences based on Φ-OTDR. Background technique [0002] Phase sensitive optical time domain reflectometer (Φ-OTDR) is a new type of distributed optical fiber sensing technology. The same as the conventional optical time domain reflectometer (OTDR), the optical pulse is injected from one end of the optical fiber, and after being detected by the detector, it scatters the light to Rayleigh to judge the disturbance and fault location; the difference is that the Φ-OTDR system injects a strong For coherent light, what is detected is the result of the interference of Rayleigh scattered light in the pulse width range. The position of the interference point can be judged by measuring the time delay between the input pulse and the received interference signal...

AI Technical Summary

Problems solved by technology

[0003] In practical applications, although the distributed fiber optic fence intrusion monitoring system has many outstanding advantages compared with other systems, due to the long monitoring distance, sensitivity to external environmental interference, and the optical system is easily affected by the external environment and temperature, the monitoring signal signal is unstable. The noise ratio is low, and its own fluctuations make it difficult to detect intrusions, and the system false alarm rate is high

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