DFT, 2 Sinusoids with Hamming Window.

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. The spectra when a Hamming window is applied to the signal is also shown.

eg parameters:-
(3.0, 3.5, 0.01, 12.34, 55, NA, 15, 10.0, 34.5, 0.3) here the unwindowed spectrum correctly shows 2 lines at 3 and 3.5rad/s while the windowed spectrum shows 4 lines at 2.5, 3, 3.5, 4rad/s.
(3.0, 3.5, 0.01, 13.27, 55, NA, 15, 350.0, 34.5, 0.3) here the unwindowed spectrum shows a psk spectrum with frequencies from 0 to ws/2 with highest peaks at 2.79 and 3.72rad/s. while the windowed spectrum shows 5 lines at 2.325, 2.79, 3.255, 3.72, 4.185rad/s.








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COPYRIGHT 2007 Cuthbert Nyack.