Savitzky-Golay least-squares polynomial filters in ECG signal processing

The Savitzky-Golay(SG) filters are widely used for smoothing and differentiation in many fields namely in elastography, EEG and magnetocardiogram signal processing and mainly in absorption spectroscopy. Despite their exceptional features they were rarely used so far in the ECG signal processing. The aim of this paper is the investigation of their properties in detail from the ECG signal processing aspect. There were considered smoothing and differentiation filters approximating polynomials of zero to fourth order with 3-25-point lengths. The filtering effect and the retaining of small details of signal are opposite requirements and depend on the length and the order of applied polynomial. Taking into consideration 500 Hz sampling rate, size of smallest relevant ECG and requirements of approximating peaks and inflections in ECG signal processing, the best choice of use is the quartic smoothing and differentiation filters with 17-point length