Powerline interference reduction in ECG signals using variable notch filter designed via variational mode decomposition

Abstract

For cardiovascular disease diagnosis, the utility of the Electrocardiogram (ECG) signal is comprehensive. For accurate ECG analysis, early diagnosis and evaluation of cardiac disorders, embedded low and high-frequency noise must be eradicated from it. Baseline wandering is an example of low-frequency noise, whereas muscle artefacts and power line interference are examples of high-frequency noise. This paper presents a novel method for cancellation of power line interference that is based on variational mode decomposition (VMD) and digital filtering techniques. To accomplish an efficacious ECG denoising process, narrow-band variational mode functions (VMFs) are created by decomposing the noisy ECG signal using VMD method. The aim is to eliminate powerline interference noise (PLI) using a variable notch filter designed using these narrow-band VMFs. For cancellation of powerline interference, centre frequency of all VMFs is estimated and depending upon the presence of powerline interference, a notch filter with frequency response adjusted to the estimate obtained from VMFs is designed to remove it. Utilizing the signal-to-noise ratio (SNR) and correlation coefficient, the effectiveness of the suggested denoising method is evaluated. The proposed approach is tested on synthetic ECG signals and standard MIT-BIH arrhythmia database, demonstrating that the proposed approach reduces powerline interference noise better than the current state of art methods.