[An optimized filter system for eliminating 50 Hz interference from high resolution ECG]

A 50/60 Hz notch filter system was designed to eliminate powerline interferences from the high-resolution ECG. This special filter causes only minimal distortions of the power spectra and thus permits us to filter high-resolution ECG's without any appreciable changes in the frequency distribution of the original signal. Since the filter is based on an integer coefficient filter technique, the calculation time is relatively short, and the programming effort comparatively low. Three different automatically selected transfer functions ensure that an optimal filtered signal is obtained despite variations in the value of the interference.