The invention discloses a
wavelet noise reduction and gradient
feature extraction method for buried pipeline
welding seam positioning, and relates to the technical field of
nondestructive testing. The method comprises: acquiring an original
magnetic field signal of a pipeline area through a
magnetic field acquisition device;
wavelet transformation is carried out on the
signal,
wavelet reconstruction is carried out after a
noise coefficient is suppressed through threshold
processing, and a denoised
signal is obtained; finally, gradient
feature extraction is conducted, specifically, the gradient of the denoised signal is calculated and standardized, extreme points in the standardized gradient are recognized by setting a threshold value to serve as
welding seam feature points, and therefore accurate positioning of the
welding seam position is achieved. According to the method, non-periodic
noise is effectively filtered through wavelet transformation,
gradient analysis is combined to strengthen and extract the
magnetic field abrupt change features of the welding seam, the problem that a traditional
frequency domain method is poor in adaptability in buried pipeline welding seam positioning is solved, and the method has the advantages of being good in filtering effect, accurate in
feature extraction and high in robustness.