Digital Sound & Music: Concepts, Applications, & Science, Chapter 6, last updated 6/25/2013
54
axis([0 132300 -2 2]);
figure;
plot(m);
axis([0 132300 -2 2]);
figure;
plot(AM2);
axis([0 132300 -2 2]);
wavplay(c, 44100);
wavplay(m, 44100);
wavplay(AM2, 44100);
carrier wave
,modulator wave
result of amplitude modulation
Figure 6.50 Amplitude modulation of a complex audio signal
The audio effect is different, depending on which signal is chosen as the carrier and
which as the modulator. Below, the carrier and modulator are reversed from the previous
example, generating the graphs in Figure 6.51.
N = 132300;
r = 44100;
m = wavread('HornsE04.wav');
n = [1:N];
c = sin(2*pi*10*n/r);
c = transpose(c);
AM3 = c .* (1.0 + m);
figure;
plot(c);
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