High-precision optical fiber strain low-frequency sensing demodulation method based on wavelet cross-correlation technology

Abstract

The invention discloses a high-precision optical fiber strain low-frequency sensing demodulation method based on a wavelet cross-correlation technology. The high-precision optical fiber strain low-frequency sensing demodulation method comprises the steps data are preprocessed, wherein wavelet denoising processing is conducted on a reference fiber bragg grating reflectance spectrum and a sensing fiber bragg grating reflectance spectrum, and zero setting processing is conducted on data outside the bandwidth of the denoised reference fiber bragg grating reflectance spectrum and the bandwidth of the denoised sensing fiber bragg grating reflectance spectrum, so that the preprocessed reference fiber bragg grating reflectance spectrum and the preprocessed sensing fiber bragg grating reflectance spectrum are obtained; wavelet domain cross-correlation is conducted, wherein a wavelet domain cross-correlation value of the preprocessed reference fiber bragg grating reflectance spectrum and the preprocessed sensing fiber bragg grating reflectance spectrum is calculated; peak value detection is carried out, wherein the peak value position of the wavelet domain cross-correlation value is obtained, and the external strain value corresponding to the sensing fiber bragg grating reflectance spectrum is obtained according to the peak value position.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a high-precision optical fiber strain low-frequency sensing demodulation method based on wavelet cross-correlation technology. Background technique [0002] Over the past two decades, with the rapid development of optical fiber sensing and optical fiber communication technology, various types of optical fiber sensors (such as Michelson interferometric optical fiber sensors, Fapper interferometric optical fiber sensors, fiber grating sensors, etc.) industry have been widely used. The use of fiber optic sensors for strain measurement is the most common form of application, among which fiber optic grating (FBG) sensors have been a research hotspot in this field due to their advantages of small size, fast response speed, wide range of linear response, and easy reusability. . [0003] At present, the strain measurement accuracy of the FBG strain interrogator widely use...

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Problems solved by technology

[0008] In view of this, the main purpose of the present invention is to provide a low-frequency demodulation algorithm for high-precision optical fiber strain sensing, which uses wavelet transform technology to calculate the cross-correlation of the reflection spectra of two optical fiber sensors in the wavelet domain, so as to improve the accuracy of optical fiber measurement of low-frequency strain. Demodulation accuracy, and focus on solving the problem that the traditional cross-correlation-based optical fiber sensing demodulation algorithm cannot be used for high-precision demodulation of non-stationary fiber grating sensing signals, requires prior knowledge of known optical fiber sensing signals and noise, and requires optical fiber sensing Independence of signal and noise

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