Data demodulation method for polarization maintaining fiber stress sensing

Abstract

The invention discloses a data demodulation method for polarization maintaining fiber stress sensing. The method comprises the following steps of: acquiring an interference signal by using a polarization maintaining fiber stress sensing test system to acquire photovoltage data; pre-processing the photovoltage data, averaging every n points to acquire new photovoltage data, and data volume; decomposing a photovoltage data signal into an intrinsic mode function (IMF) component and an allowance by an experimental mode method; finding out a basic component and identifying a small coupling point; reconstructing coupling intensity of a signal, and calculating the stress magnitude through intensity of each coupling point so as to realize the distributed detection of a system; and calculating indexes which can show the system test accuracy, such as a signal-to-noise ratio and the like. The method can effectively improve the signal-to-noise ratio of the polarization maintaining fiber stress sensing system, and improves the identification capacity of weak coupling points and the sensitivity of a coupling test. Under the environment of relatively low signal-to-noise ratio, microstress can be detected well.

Description

Data Demodulation Method for Polarization Maintaining Optical Fiber Stress Sensing technical field The invention relates to a method for measuring stress parameters of a polarization device, belonging to the technical field of optical measurement, in particular to a data demodulation method for stress sensing of an optical polarization-maintaining device based on an interferometry method. Background technique When the polarization-maintaining fiber is disturbed by external force, magnetic field, bending, torsion and other factors, polarization coupling will occur. The measurement of polarization-maintaining fiber polarization coupling can realize the sensing of disturbance physical quantity. White-light interferometric polarization-coupled distributed polarization-maintaining fiber optic sensors have been widely used in stress, strain, temperature, gas, and position sensing due to their high spatial resolution and wide dynamic range. Its biggest feature is that it can real...

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Problems solved by technology

When the useful information of the signal and the frequency band of the noise do not overlap, the Fourier smoothing filter can achieve better results. However, setting a specific cutoff frequency is not suitable for nonlinear noise and signal structures with sudden changes.

In wavelet transform, once the wavelet base is selected, it cannot be replaced in the whole process of decomposition and reconstruction, and there is no local adaptability to the signal

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