File:Sampled signal DFT time aliasing.pdf

Description
English: Example of aliasing in time (visible especially around the origin), due to too low time interval , of a sampled analogue signal.
Italiano: Esempio di aliasing nel tempo (visibile soprattutto intorno all'origine), dovuto a intervallo di tempo troppo basso, di un segnale analogico campionato.
Date
Source Own work
Author Luca Ghio
Permission
(Reusing this file)
Public domain I, the copyright holder of this work, release this work into the public domain. This applies worldwide.
In some countries this may not be legally possible; if so:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.
Category:Self-published work#Sampled%20signal%20DFT%20time%20aliasing.pdfCategory:PD-self#Sampled%20signal%20DFT%20time%20aliasing.pdf
gnuplot source
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fc=4 * 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--')
Category:Images with Octave source code Category:Created with GNU Octave Category:Plots of discrete time Category:Aliasing
Category:Aliasing Category:Created with GNU Octave Category:Images with Octave source code Category:PD-self Category:Pages using deprecated source tags Category:Plots of discrete time Category:Self-published work