High-precision fiber grating demodulation method based on Hilbert transform and bispectrum estimation

Abstract

The invention discloses a high-precision fiber bragg grating demodulation method based on Hilbert transformation and bispectrum estimation. The method comprises the steps of intercepting data of two reflectance spectrums of a fiber bragg grating, carrying out Hilbert transformation on the data of the reflectance spectrums respectively, superposing the transformed data to raw data after calculating the absolute value of the transformed data to obtain X(n) and Y(n), calculating third-order cumulant and third-order cross cumulant through X(n) and Y(n) respectively, calculating bispectrum through the third-order cumulant, calculating cross bispectrum through the third-order cross cumulant, constructing a wavelength differential function with the wavelength differential as the variable through the bispectrum and the cross bispectrum, detecting the position of the maximum value of the constructed wavelength differential function to obtain the wavelength differential of the two reflectance spectrums. By means of the demodulation method, the wavelength demodulation precision can be effectively improved, and influence caused by Gaussian noise and correlated noise in the reflectance spectrum can be eliminated. The demodulation method can be applied to signal demodulation of a non-stable fiber bragg grating and does not require that fiber sensing signals should be independent from noise.

Description

Technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a high-precision optical fiber grating demodulation method based on Hilbert transform and bispectrum estimation. Background technique [0002] Optical fiber sensing technology developed rapidly with the development of optical fiber communication technology in the 1970s. The working frequency bandwidth of the optical fiber and the large dynamic range are suitable for remote measurement and remote control. It is an excellent low-loss transmission line. Under certain conditions, it is also an excellent sensitive component. In view of this, various types of optical fiber sensors have been born and have been widely used in various fields. Among them, it is very common to use fiber grating (FBG) sensors for strain measurement. [0003] Nowadays, fiber grating sensors have been widely used in strain measurement of smart materials and structures, and the detection accuracy of F...

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Problems solved by technology

[0007] In view of this, the main purpose of the present invention is to provide a high-precision fiber grating demodulation method based on Hilbert transform and bispectrum estimation, to improve the demodulation accuracy of fiber grating measurement strain, and focus on solving the traditional cross-correlation solution The modulation method cannot effectively suppress Gaussian noise and correlation noise, and cannot be used for high-precision demodulation of non-stationary FBG sensing signals.

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