Characterization and elimination of AC noise in electrocardiograms: a comparison of digital filtering methods.

Diverse digital methods have been advanced previously to remove power line (AC) interference in the ECG. Representative notch filters, adaptive filters and a globally derived filter are surveyed in this study; their performances are compared on artificial signals as well as actual ECGs. The ECGs, recorded at four European medical centers, are from the Common Standards in Electrocardiography (CSE) ECG tape library. AC interference in these ECGs is shown to exhibit two qualities especially relevant to filter design: considerable deviations from a nominal 50 Hz frequency and substantial noise at higher harmonics. Some criteria and useful quantitative measures are suggested to evaluate AC digital filters.