%Ein Multiplizierer hat fe=2000Hz, Ampl. = 1; FO=2200Hz, Ampl.=1;
fa = 10000;
t = 0:1/fa:1;
fe=2000;

fo=2200;


multi = sin(2*pi*fe .* t) .* sin(2*pi*fo .* t);

plot(multi);
figure;
y_fft = fft(multi);


plot(20*log(abs(y_fft)));