File:Sampled signal DFT frequency aliasing.pdf
| Description |
English: Example of aliasing in frequency (visible especially at the edges), due to too low sampling rate , of a sampled analogue signal.
Italiano: Esempio di aliasing in frequenza (visibile soprattutto agli estremi), dovuto a frequenza di campionamento troppo bassa, di un segnale analogico campionato. |
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| Date | |||
| Source | Own work | ||
| Author | Luca Ghio | ||
| Permission (Reusing this file) |
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| gnuplot source | click to expand
fc=40.52;
N=128;
Tc=1/fc;
T0=N*Tc;
Df=1/T0;
n=[0:N-1];
x_samp=exp(-2*n*Tc);
f=[-N/2:N/2-1]*Df;
DFT=fftshift(fft(x_samp,N));
figure
set (gca,'FontSize',14)
stem(f,abs(DFT)*Tc)
xlabel('f\cdot f_c')
ylabel('|X(f)|')
axis([-20 20 0 0.6])
grid on
hold on
f=[-N/2:0.01:N/2-1]*Df;
X=abs(1./(2+j*2*pi*f));
plot(f,X,'r--')
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