Summary: Applet demonstrating the concept of aliasing
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The applet is courtesy of the Digital Signal Processing tutorial at freeuk.com, http://www.dsptutor.freeuk.com/. You can also have a look at the Light Wheel applet.
In this module we shall look at sampling a sinusoidal signal. According to the sampling theorem, a sinusoidal signal can be exactly reconstructed from values sampled at discrete, uniform intervals as long as the signal frequency is less than half the sampling frequency. Any component of a sampled signal with a frequency above this limit, often referred to as the folding frequency, is subject to aliasing.
The applet is based on a fixed sampling rate of
Set the frequency of the sinusoidal signal, in Hz, in the "Input frequency" box, i.e
choose an
The "Grid" checkbox toggles on and off vertical gridlines indicating the instants at which the signal is sampled. The "Sample points", representing the sampled values of the input signal, can also be toggled.
Finally, the "Alias frequency" checkbox
(visible only when
aliasing occurs)
controls the plotting of the "reconstructed" sinusoidal signal, with
When using the applet it is important to have an understanding of where the different signals occur in a sampling system.
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