Distributed optical fiber vibration sensing positioning method and device based on FFT

Abstract

The invention provides a distributed optical fiber vibration sensing positioning method based on FFT. The distributed optical fiber vibration sensing positioning method based on the FFT comprises thefollowing steps: performing FFT on signals accumulated at each position by collecting Rayleigh backscattered signals of a plurality of pulses; determining the frequency of the vibration signal at a position according to amplitude-frequency characteristics at the position; performing screening using the frequency as the judgment condition, and performing difference processing of adjacent moments atthe corresponding positions on the frequency results that meet the judgment condition; and identifying the true and effective vibration position accurately under the circumstance that the optical cable is affected by the external environment. The invention also provides a distributed optical fiber vibration sensing positioning device based on the FFT, which is used for performing the distributedoptical fiber vibration sensing positioning method based on the FFT. The invention determines the vibration position by combining the vibration frequency characteristics of different vibration forms and the characteristics of real vibration suddenness; the algorithm is simple to implement; and the distributed optical fiber vibration sensing positioning method and device based on the FFT has good engineering practicability.

Description

technical field [0001] The invention relates to the field of distributed optical fiber vibration sensing, in particular to an FFT-based distributed optical fiber vibration sensing positioning method and device. Background technique [0002] The distributed optical fiber vibration sensing system is composed of long-distance distributed detection optical fiber arranged at the front end, optical fiber demodulation host, and host computer software. The system uses a laser source and an acousto-optic modulator to continuously inject pulsed light into the detection fiber, and receives the back Rayleigh scattered light containing the vibration or sound signal after the detection of the vibration or sound wave signal in the sensing fiber. The sensor and acquisition card transmit the signal to the host computer for data processing, and finally demodulate the vibration information. The distributed optical fiber vibration sensing system performs all-day, all-weather long-distance cont...

AI Technical Summary

Problems solved by technology

When making early warning judgments in practical applications, the vibration signals that really need to be monitored are overwhelmed by other vibration signals around (caused by the environment), which will bring great trouble to the determination of the real vibration position and cause a high false alarm rate.

At this stage, the method of dynamic threshold and pattern recognition is mainly used to solve this problem: dynamic threshold can reduce the false alarm rate to a certain extent, but it will inevitably increase the false alarm rate; pattern recognition can judge the type of vibration, but the algorithm realizes complex, low availability

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