Design of Fractional Filters for Power-line Interference Suppression in ECG Signals

The sampling interval is the unit step in which a discrete biosignal can be easily shifted during the digital filtering process. It allows the design of linear-phase filters with constant group delay characteristics. In many cases, the sampling interval is insufficiently short to ensure the required frequency response of the filter. This paper presents a novel approach for design of fractional filters, which is applied to several common types of comb filters. The effectiveness of the approach is illustrated by filtering of the power-line interference in real ECG signals. The presented fractional filters have a simple design, which is suitable to different biosignal acquisition applications where filtering of various noises is strongly mandatory.