a signal evaluation method for detecting qrs complexes in electrocardiogram signals incorporates the following process steps : sampling of the signal and conversion to discrete signal values ) in chronological order , determining the sign of each signal value ), continuous checking of the signs of consecutive signal values ) for the presence of a zero crossing between two consecutive signal values ), determining the number ) of zero crossings in a defined segment of the consecutive signal values ), and comparing the determined number of zero crossings ) to a defined threshold value , wherein an undershoot of the threshold value signifying the presence of a qrs complex in the defined segment of the signal curve .