6.3 Signals of the Cardiovascular System

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Fig. 6.40: Top: Result of the autocorrelation of the signal from Figure 6.39 (bottom). The main max-

ima correspond to a shift of one heart period, the first minor maximum to the right of a major max-

imum corresponds to a shift by LVET. On the abscissa the displacement is given in samples. The

sample frequency here is 8 kHz. Bottom: Magnification of the AKF around the main maximum. The

distance of the main maximum to the next right side maximum corresponds to the searched LVET.

% Plot of raw signal

figure1 = figure;

plot(ts, x);

xlabel('t / s');

ylabel('s(t)');

title('Phonokardiogram');

% Plot of absolute values

x1 = abs(x);

figure2 = figure;