Signal Processing Techniques for Removing Noise from ECG Signals

The electrocardiogram (ECG) signals contain many types of noises-baseline wander, powerline interference, electromyographic (EMG) noise, electrode motion artifact noise.Baseline wander is a low-frequency noise of around 0.5 to 0.6 Hz.To remove it, a high-pass filter of cut-off frequency 0.5 to 0.6 Hz can be used.Powerline interference (50 or 60 Hz noise from mains supply) can be removed by using a notch filter of 50 or 60 Hz cut-off frequency.EMG noise is a high frequency noise of above 100 Hz and hence may be removed by a low-pass filter of an appropriate cut-off frequency.Electrode motion artifacts can be suppressed by minimizing the movements made by the subject.The chapter introduces the types of common noise sources in ECG signals and simple signal processing techniques for removing them, and also presents a section of Matlab code for the techniques described.