A FFT-based distributed optical fiber vibration sensing positioning method and device

Abstract

The present invention provides an FFT-based distributed optical fiber vibration sensing positioning method. By collecting the Rayleigh backscattering signals of multiple pulses, FFT is performed on the signals accumulated at each position. According to the amplitude-frequency characteristics at the position, Determine the frequency of the vibration signal at this position, use the frequency as the judgment condition to screen, and process the frequency results that meet the judgment conditions with the difference at the corresponding position at adjacent times, and accurately identify the real and effective vibration position when the optical cable is affected by the external environment. The present invention also provides an FFT-based distributed optical fiber vibration sensing and positioning device, which is used to implement the aforementioned positioning method. The invention judges the vibration position by combining the vibration frequency characteristics of different vibration forms and the real vibration suddenness characteristics, the algorithm is simple to realize, and 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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