DFT, 2 Sinusoids.
Cuthbert Nyack
In this applet a section of 2 sinusoids from T1 to T2 is sampled and
the DTFT and DFT calculated. The variation of the spectra as T1, T2
are changed is illustrated.
eg parameters:-
(3.0, 4.0, 0.01, 6.04, 25, NA, 15, 10.0, 15.0, 0.7) and
(3.0, 4.0, 0.01, 6.93, 25, NA, 15, 200.0, 15.0, 0.7) show the
same phenomemon which occurs for a single sinusoid.
To separate the 2 frequencies, then the sampled interval and
number of samples must be chosen so that the DFT line separation
must be equal to or be a submultiple of the difference between the
2 frequencies. eg:-
(3.0, 3.2, 0.01, 31.02, 80, NA, 45, 10.0, 34.5, 0.2) Sampling
frequency = 16rad/s, line separation = 0.2rad/s, frequency separation = 0.2rad/s.
(3.0, 3.4, 0.01, 31.11, 100, NA, 45, 10.0, 34.5, 0.2) Sampling frequency
= 20rad/s, line separation = 0.2rad/s, frequency separation = 0.4rad/s.
(3.0, 4.0, 0.01, 31.11, 100, NA, 45, 10.0, 34.5, 0.2) Sampling frequency
= 20rad/s, line separation = 0.2rad/s, frequency separation = 1rad/s.
Return to main page
Return to page index
COPYRIGHT © 2007 Cuthbert Nyack.