Optical frequency domain reflection-distributed vibration frequency sensing and locating device and demodulation method

Abstract

The invention discloses an optical frequency domain reflection-distributed vibration frequency sensing and locating device and a demodulation method. A technical method of optical frequency domain reflection beat frequency interference of a self-injective mode locking laser of a linear turning ultra-narrow linewidth whispering gallery mode is adopted in the optical frequency domain reflection-distributed vibration frequency sensing and locating device. The optical frequency domain reflection-distributed vibration frequency sensing and locating device comprises a main interferometer which is used to obtain a sensing signal and an auxiliary interferometer of a clock trigger signal. The demodulation method comprises that wavelength domain information is obtained by the main interferometer, fast Fourier transform is used to transform the wavelength domain information, and then distance domain information is obtained. A group of static reference signals and a group of vibration signals are collected. The distance domain information, namely local distance domain information, is selected in sequence by moving windows. Complex number cross correlation is used on the static signals and the vibration signals of the local distance domain information on each position. According to a noise coefficient of the complex number cross correlation, a position of a vibration point is obtained. A subsidiary summit position of the complex number cross correlation of the local distance domain information on the position of the vibration is picked up, and the subsidiary summit position is vibration frequency information.

Description

technical field

[0001] The invention belongs to the technical field of distributed optical fiber sensing instruments, and in particular relates to a distributed vibration frequency sensing and positioning device and a demodulation method based on an optical frequency domain reflection method. Background technique

[0002] With the continuous development of society, the health and safety monitoring of large building structures such as bridges, culverts, tunnels, and dams is particularly important. Among them, the structural vibration frequency information is an important parameter for structural health and safety monitoring, because the eigenfrequency is an important indicator for evaluating the structural health and judging the early damage of the building.

[0003] The distributed optical fiber vibration sensing system can realize vibration frequency detection and positioning of vibration points, and has the characteristics of long-distance monitoring, high-precision positi...

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