A method for generating determination indexes for identifying ECG interfering signals includes acquiring ECG signals to obtain a sequence of data values representing original ECG signals; dividing the sequence of data values acquired during a period of time into groups and collecting all the minimum data values in their respective groups on a statistical basis; determining the minimum and the maximum data values in a minimum set made up of all the minimum data values in their respective groups; and using the difference between the minimum and the maximum data values as a first baseline drift determination index to identify at least one of low frequency interference and irregular interference.