The idea of the algorithm is to use the QRS complex detection algorithm result to determine an R-to-R interval classification and to estimate the width for each beat. According to the basic detection rules, the peak will determine whether it is larger than a detection threshold and i.e. it is a QRS complex; otherwise, it is called ‘noise’. If an interval is equal to 1.5 times the average of an R to R interval, it is counted as a peak, in case it is larger than half of the detection threshold, and the peak pursued the preceding detection by at least 360 ms. Then the peak is classified as a QRS complex. Depending on these two detection rules, it can estimate the QRS peak and noise peak. Also from the R-to-R interval it can calculate the mean of the last eight R-to-R intervals.