Ultrasound signal de-noising method based on correlation analysis and empirical mode decomposition

Abstract

The invention provides an ultrasound signal de-noising method based on correlation analysis and empirical mode decomposition (EMD). The method comprises the following steps: firstly fitting the energy curve of the pure noise under ultrasound empty acquisition state to obtain a trend curve Alpha of the noise which changes along with time gain compensation (TGC); then dividing the normally acquired ultrasound echo signals with two continuous frames into two parts, one of which is called main noise signal, the dot product of the echo signals and the Alpha curve and the other of which is called main useful signal, the difference of the echo signals and the first part; carrying out EMD on the main noise part to obtain the energy ratio of the first intrinsic mode function (IMF) component as the weighting coefficient of the signals with two frames and carrying out threshold processing after carrying out correlation analysis on the corresponding IMF component; and finally obtaining the de-noised signal after carrying out weighting reconstruction on the main noise part and the main signal part. The invention has adaptive signal decomposition and noise reduction capabilities, greatly improves the signal to noise ratio of the ultrasound signal and obtains good de-noising effect.

Description

technical field [0001] The invention relates to an ultrasonic signal denoising method, in particular to an ultrasonic signal denoising method based on correlation analysis and empirical mode decomposition. Background technique [0002] Ultrasonic imaging technology has the advantages of good real-time performance, no damage, no ionizing radiation, and convenient use, so it has been widely used in clinical diagnosis. When ultrasonic waves propagate in human tissue, energy loss such as reflection and absorption will inevitably be caused. Therefore, as the detection depth deepens, the echo signal will weaken and the signal-to-noise ratio will decrease. Therefore, TGC-TimeGain Compensation amplifiers are usually used to correct The echo signal is compensated, and the far-field noise is also amplified to a certain extent, forming a noise with small near-field noise and large far-field noise, which is a time-varying noise [1] . [0003] The existence of noise in ultrasound signa...

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Problems solved by technology

[0005] The amplitude and frequency of noise in ultrasonic signals are constantly changing, so it is suitable to be processed by time-frequency analysis method. Traditional analysis methods mainly include Fourier transform, short-time Fourier transform, wavelet transform, etc. [7] , due to the limited ability of these transformations to process non-stationary and nonlinear signals, the basis functions with exact expressions lead to poor adaptability, and the EMD method is an adaptive signal processing method with adaptive The ability of signal decomposition and noise reduction, so the EMD method can be applied to ultrasonic signal denoising

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