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A technique to remove baseline wander (BW) from electrocardiogram (ECG) signals based on the Hilbert vibration decomposition (HVD) technique is presented. It is proposed that the first component (highest energy component) obtained using the HVD of the ECG signal corresponds to the BW signal in it. The proposed technique is compared with the baseline removal method based on the empirical mode decomposition technique and mathematical morphology in terms of the correlation criterion and signal-to-noise ratio. The simulations were performed using artificial BWs of different amplitudes added in the ECG recordings and it is seen that the proposed technique for BW removal performs better in most of the cases of severe baseline wander distortions.Introduction: Baseline wander (BW) of the electrocardiogram (ECG) is mainly caused by the movement and respiration process of the patient and it mainly appears as low-frequency artefacts in the ECG signals [1][2][3][4]. Removal of BW is necessary for better visual interpretation, and detection of certain patterns in the ECG signal for subsequent automatic processing. The use of highpass filtering for BW removal is not recommended as it can distort the ECG waveform because of variations in the frequency spectrum of the ECG signal [2]. A nonlinear filter bank technique is proposed for BW removal without distorting the ECG signal [3]. The empirical mode decomposition (EMD) technique has also emerged as a tool for time-frequency analysis and is being used in a number of applications [5]. By using the EMD, the ECG signal can be decomposed in a series of intrinsic mode functions (IMFs) [4]. In the method proposed in [4], the higher-order IMFs are used to obtain the BW signal. These higher-order IMFs obtained by the EMD technique are filtered through a lowpass filter to obtain the BW of the ECG signal. A similar technique for BW removal based on the EMD technique is also proposed in [2] where the lowpass filter is designed by averaging two basic morphological operators: opening and closing.Recently the Hilbert vibration decomposition (HVD) technique has attracted the attention of the researchers and it decomposes the nonstationary wideband signals into a sum of components with slowly varying amplitudes and frequencies [6]. In the HVD technique, the first component represents the highest instantaneous amplitude component and the residue signal contains information of the lower amplitude components [6]. In this Letter, an approach for BW removal based on the HVD technique is proposed. The main motivation for using the HVD technique stems from the fact that the BW component in the ECG signal generally has a significant fraction of the total energy of the ECG signal. Thus, the BW signal can be obtained from the highest energy component (first iteration) of the HVD.

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