Safety monitoring system and method for circumference

Abstract

The invention discloses a perimeter security monitoring system. A light source, an optical isolator and a port B of a beam splitter 3 are connected through an optical fiber in sequence, the beam splitter 3 is connected with a beam splitter 4 through a sensing optical fiber, the port a of the beam splitter 4 is connected with a reflecting mirror through a phase modulator, the port b of the beam splitter 4 is connected with a delay winding through the phase modulator, and the delay winding is connected with the reflecting mirror. When the sensing optical fiber vibrates along the line, the two paths of interference optical signals carried with the same vibration information reach an photoelectric detector from the port A of the beam splitter 3, the analog signal is transformed into a digital signal through a data acquisition unit, the digital signal is transmitted to a computer, and the positioning of a vibration source is obtained by a formula, i.e. z is equal to LD*phi s(t) / phi M-Z (t). The invention can monitor the perimeter vibration conditions at real time, has very high sensitivity and positioning accuracy and reliably runs.

Description

technical field [0001] The invention relates to the field of public security protection, in particular to a perimeter security monitoring system and a perimeter security monitoring method using the system. Background technique [0002] In recent years, with the development of optical fiber sensing technology, long-distance distributed optical fiber sensing technology has also begun to be applied to perimeter security monitoring. Compared with the traditional perimeter security system, the fiber optic perimeter security system is a non-destructive security system, which has the advantages of anti-electromagnetic interference, corrosion resistance, strong concealment, low power consumption, and long life. [0003] Aiming at the problems existing in the existing perimeter security monitoring technology, an attempt is first made to implement perimeter security monitoring by using OTDR (Optical Time Domain Reflectometer, Optical Time Domain Reflectometer) technology. Its essence...

AI Technical Summary

Problems solved by technology

Its essence is light radar technology, which is to judge the disturbance of the optical fiber and locate it by sending narrow light pulses into the optical fiber and detecting the Rayleigh scattering and Fresnel reflection signals generated in the optical fiber, but the disadvantage is that the signal noise is too large , the signal processing time is long, and real-time monitoring cannot be carried out, so the practical significance is not great

This invention is a breakthrough for the safety monitoring technology of large-scale perimeter, but the disadvantage is that the optical path system in this invention is unstable, and there is signal blanking caused by phase fading and polarization fading, so it is difficult to work effectively

The disadvantage of this technology is that: since the two sensing fibers are relatively close to each other, the vibration along the sensing fiber may make the phase delays of the two sensing fibers consistent, so that there is no interference and a reciprocity effect occurs; in addition, only the captured The start time of the intrusion vibration signal can only be located. When the intrusion vibration signal has occurred, the intrusion point positioning function will no longer be available.

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