A Low-Power Non-Uniform Third-Derivative-Based Sampling Technique for ECG Applications

In this work, we present an approach called third-derivative-based sampling (TDS), which is a non-uniform sampling technique that can be used in a variety of applications. Here, we will focus on applying the technique to electrocardiogram (ECG) signals. We also present a possible hardware implementation of the approach. The TDS method uses cubic spline interpolation for sampling the signal as well as signal reconstruction. As compared to other non-uniform sampling techniques, TDS offers an improved accuracy of the reconstructed signal and/or a reduction in the number of retained samples which enhances the compression factor (CF). Such improvements will also lead to an enhanced power efficiency in ECG monitoring systems. Users can control the associated reconstruction error by adjusting the maximum number of samples that can be disregarded (N) and/or the magnitude of the fourth derivative of the signal. The presented results demonstrate that the proposed method can offer up to 20% improvement in the CF as compared to the state-of-the-art techniques reported in the literature without compromising the reconstruction error. Alternatively, it can offer up to 53% enhancement in the accuracy of the reconstructed signal for a given CF. By integrating the proposed TDS block into an ECG data acquisition and processing system, the overall power consumption of the system can be reduced since only a small fraction of samples (proportional to CF) are kept and processed.