Fig. 4

Detection of atrial fibrillation. a Pipeline for the atrial fibrillation detection algorithm (band-pass filter, top: autocorrelation, absolute value, integration; bottom: fast Fourier transform, absolute value, spectral entropy; classification). b Five second measurement of a healthy 34-year-old male. c Typical atrial fibrillation recording of 5 s. d and e The corresponding absolute value of the autocorrelation of b and c. f Clustering of healthy (n = 13) and atrial fibrillation patients (n = 7) using time–frequency analysis