DTFT and FT of 2 Sinusoids.
The applet below shows the Discrete Time and Continuous Time
Frequency Transforms of a function
f(t) = (0.6 * sin(w1t) + 1.4 * sin(w2t))/2.
(3.0, 8.0, 1.81, 12.07, 50, NA, 50, 10.0, 0.4), for frequencies up
of both the CTFT and the DTFT has components at 3rad/s and 8rad/s. The
DTFT also has frequencies at 22rad/s and 27rad/s.
Increasing w2 to 16rad/s shows the CTFT
has lines at 3 and 16rad/s while the DTFT has lines at 3, 14, 16 and
27rad/s. Between 0 and ws/2
the DTFT has lines at 3 and 14rad/s. This is an example of Aliasing.
Increasing w2 to 29rad/s shows the
CTFT has lines at 3 and 29rad/s while the DTFT has lines at
1, 3, 27 and 29rad/s. Between 0 and ws/2
the DTFT has lines at 1 and 3rad/s. Another example of Aliasing.
Return to main page
Return to page index
© 2007 Cuthbert A. Nyack.