Figure 3
From: Algorithm for identifying and separating beats from arterial pulse records
Different stages while processing a typical signal. S is the original signal; S' b is the binarized first derivative; S'' r is the rectified second derivative; W1 is the weighing signal showing all spikes detected by marks; W2 is the same weighing signal, with only those spikes preserved by the weighed filter. W3 is the same weighing signal with only those spikes preserved by the frequency filter. The bottom trace represents again S, with all onsets and ends well identified. Tolerance values were Tol1 = 0.4 and Tol2 = 0.2.