De-Noising of ECG Signal Using Translation- Invariant Wavelet De-noising Method with Improved Thresholding

The electrocardiogram (ECG) signal may mix various kinds of noises while gathering and recording. Wavelet thresholding de-noising method based on discrete wavelet transform (DWT) proposed by Donoho et al. is often used in de-noising of ECG signal. According to the defects of Donoho's method in de-noising of ECG signal, this paper proposes an improved thresholding de-noising method based on Donoho's method. The advantage of the improved de-noising method is that it may not only remain the geometrical characteristics of the original ECG signal and keep the amplitudes of various ECG waveforms efficiently, but also suppress impulsive noise to some extent. Furthermore, the traditional wavelet thresholding de-noising method causes Pseudo-Gibbs phenomena in Q and S waves of ECG signal due to DWT. In order to suppress Pseudo-Gibbs phenomena in Q and S waves, a new de-noising method combining above improved thresholding with the translation-invariant wavelet transform is proposed in this paper. The experimental results indicate that the proposed methods in the paper are better than traditional wavelet thresholding de-noising methods in aspects of remaining geometrical characteristics of ECG signal and the signal-to-noise ratio (SNR).