Abstract:
Electrocardiograms (ECG) are extensively used to monitor the electrical
activities of the heart. It is a valuable tool, especially for the initial medical
diagnosis of different heart diseases. However, because of the weak nature of
signals, ECGs easily get adulterated with distortions such as noise and baseline
fluctuations. Although Savitzky-Golay (SG) filters are often used to remove
such distortions from ECGs, they have limited distortion filtering efficiencies.
This is because in SG filters a polynomial curve fitting process is employed,
and it is not possible to directly specify the distortion removal frequency
bands. In contrast to SG filters, Multichannel Filter Banks (MFB) realized by
stable digital impulse responses would have higher distortion filtering
efficiencies due to the ability to remove only the undesirable distortions based
on the frequency sub-band characteristics, while preserving the valuable
features of the ECG signals. Thus, to remove the distortions in ECGs more
efficiently, in this paper we have proposed and developed a new band-pass
MFB filter, using a two-band filter bank as the building block. Using
experimental techniques, the ECG signal distortion removal efficiencies for
the proposed MFB and SG filters were estimated and compared by evaluating
the output Signal to Noise Ratios (SNR) for different input signal SNR levels.
Adulterated ECGs were cleaned using the MFB and SG filters. While having
the ability to simultaneously remove different kinds of ECG signal distortions,
significantly improved distortion removal efficiencies indicated by an average
SNR increase of 3.2 dB in the filtered ECG signals were observed by the
proposed MFB filter when compared with the SG filter.
