Sub-Nyquist Sampling of ECG Signals Based on the Extension of Variable Pulsewidth Model

Abstract

To prevent lifestyle diseases, portable heartbeat detection systems by electrocardiograms (ECGs) for daily life monitoring have attracted attentions. For portable systems, power consumption is critical and it is thus beneficial to reduce the sampling frequency at the point of acquisition. Recent developed variable pulsewidth finite rate of innovation (VPW-FRI) framework provides an effective way for low-rate sampling and compression of ECG signals. Unfortunately, noise and model mismatch will induce inaccuracies to such scheme in the reconstruction process. In this article, a sub-Nyquist sampling scheme based on the extension of VPW model is proposed for ECG signals, which reduce the model dismatch error, and improve the reconstruction quality under model mismatch and noise scenario. In the proposed scheme, ECG signal is modeled as the differentiated VPW model to reduce the model mismatch error. Then a FRI sampling framework based on the differentiated VPW model is proposed to sample the ECG signal at a sub-Nyquist rate. After the ECG signal is sampled, some consecutive Fourier series coefficients are calculated according to the samples. Then a modified annihilating filter algorithm is proposed to estimate parameters of the ECG signal and reconstruct the ECG signal. Finally, simulation experiments with real ECG signals from Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) Arrhythmia Database have shown that the proposed scheme outperformed the traditional methods for model mismatch. The signal-to-residual ratio (SRR) of the reconstructed signal of the proposed scheme is higher than that of the VPW-FRI scheme.