01-08-2012, 02:52 PM
Discrete Fourier Transforms
DFT.ppt (Size: 849 KB / Downloads: 27)
Fourier Transform Computation
Numerical computation of Fourier transform of f(t) using Digital Computer requires discrete data i.e. samples of f(t).
The computed Fourier spectrum also has only discrete values since computer can compute F(ω) only at some discrete values (samples) of ω.
Moreover if the signal repeats every T0 seconds,
then according to the spectral sampling theorem ,
such operation results in spectrum samples that
are spaced at f0 = 1/T0 Hz.
For non periodic sequences, one sequence is fixed and the other sequence is inverted and moved past the fixed sequence, one digit at a time.
For two N0 - periodic sequences, the same
configuration will repeat after N0 shifts of the
sequence.