The description of the main steps of the method for determining the coordinates of the extrema of periodic signals is given. This method is based on multi-start optimization using the wavelet transform. Such an approach makes it possible to increase noise resistance and reduce sensitivity to local extrema of periodic signals. The evaluation of the possibilities of this method was carried out by determining the coordinates of the R peaks of the electrocardiograms and the intervals between them. The error in determining the duration of intervals with an increase in noise level is investigated.