Buried COTDR perimeter intrusion alarming system and signal processing method

Abstract

The invention discloses a buried COTDR perimeter intrusion alarming system and a signal processing method. The system comprises a detection optical cable arranged along the boundary of a defense region; a sensing optical fiber is arranged in the detection optical cable; the boundary of the defense region is provided with an inverted trapezoid-shaped canal; the bottom part of the canal is provided with a gravel layer; a layer of natural soil covers the gravel layer; the detection optical cable is arranged in the center position of the gravel layer; one end of the detection optical cable is connected with a monitoring host; the monitoring host comprises a strong coherent light source and a photodetector; strong coherent light as incident light pulses is injected from the incident end of the sensing optical cable; backscattering signals detected by the photodetector are signals after mutual interference of Rayleigh scattering light returned to the incident end by each point in the sensing optical cable; according to the light intensity changes of the backscattering signals, the monitoring host judges the intensity of vibration happening to the boundary of the defense area; and according to the time delay between the incident light pulses and the backscattering signals, the vibration position is judged. The system and the method have the advantages of sensitive reaction, real-time performance, high efficiency and accurate positioning.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to an underground COTDR perimeter intrusion alarm system and a signal processing method. Background technique [0002] Optical fiber perimeter security products can be divided into two types according to the installation method: hanging net and buried. The detection principle is mainly based on optical fiber interferometer technology, fiber grating vibration sensing technology and other types. Buried optical fiber perimeter security products have a relatively broad market demand in some scenarios where physical physical fences (nets) or walls cannot be installed due to their advantages of good concealment and strong anti-environmental interference. Among them, the patented fiber optic micro-vibration sensor (application number: 201210584013.9), based on the Mach-Zehnder interference principle, provides a fiber optic micro-vibration sensor. The ground tone monitoring will cause a...

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Problems solved by technology

Among them, the patented fiber optic micro-vibration sensor (application number: 201210584013.9), based on the Mach-Zehnder interference principle, provides a fiber optic micro-vibration sensor. The ground tone monitoring will cause a high false alarm rate due to the wide detection frequency; the patented buried optical fiber Grating-type perimeter intrusion detector (application number: 201410373273.0), based on the principle of fiber-optic grating sensing, provides a buried fiber-optic grating-type perimeter intrusion detector, but cannot locate the intrusion event

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