Adaptive threshold calculation method and system for vibration sensing system

Abstract

The invention provides an adaptive threshold calculation method and system for a vibration sensing system. The method comprises the following steps: obtaining a first signal and a second signal of a Rayleigh scattering curve according to whether an optical fiber is connected to an optical fiber distributed vibration sensing system or not; performing windowing and framing processing on the first signal and the second signal to obtain a third signal and a fourth signal; performing adaptive normalization processing on the third signal by using the fourth signal to obtain a fifth signal; performing high-pass filtering processing on the fifth signal in a time domain to obtain a filtered sixth signal; calculating short-time energy and a short-time over-threshold rate of the sixth signal in realtime, and solving a set threshold by using an adaptive method; and solving a joint threshold by using the short-time energy and the short-time over-threshold rate, and judging the short-time energy and the short-time over-threshold rate by using the joint threshold to identify the position of the intrusion alarm. Threshold parameters are iteratively updated in real time, and false alarm caused bydrifting of the system, environmental noise and the like is effectively restrained.

Description

technical field [0001] The present invention relates to the application field of optical fiber vibration sensing for security systems, in particular, to an adaptive threshold calculation method and system for a vibration sensing system, and more specifically, to design a method for realizing optical fiber distributed vibration sensing Adaptive Threshold Algorithm for Sensitive Systems. Background technique [0002] The optical fiber distributed vibration sensing system is realized based on the phase-sensitive optical time domain technology, that is, the location of the event is determined by detecting the return time of the light pulse, the pulse width determines the spatial accuracy, and the returned coherent Rayleigh scattered light The intensity reflects the change of vibration, which uses optical fiber as a sensor to detect external disturbances and judge whether it is intruded through signal processing. Compared with many traditional sensing fields, optical fibers have...

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Problems solved by technology

Due to the different sensitivities of optical fiber sensing arrays, the sensitivity of the same location (sensor) will also drift to a certain extent with the environment, which is equivalent to intrusions of different intensities. The sensitivity of the sensors at various places in the optical fiber is artificially set with different thresholds and the thresholds need to be updated from time to time. This will not only cause false alarms due to the influence of the environment, but also bring great inconvenience in practical applications and limit the optical fiber distributed vibration sensing system. Therefore, it is necessary to study an adaptive threshold algorithm based on the characteristics of fiber optic distributed vibration sensors

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