DFT, 8 Samples with Zero Padding.
In some cases, the number of available samples is limited and this
leads to a DFT spectrum consisting of an undesirably small number
One way in which the number of lines in the spectrum can be increased
is by "zero padding" ie adding zeros to the end of the signal to
increase the effective N of the signal. Since the number of lines
in the spectrum between 0 and ws
is N, then this proceedure increases the number of lines in the
spectrum of the signal.
The effect is illustrated in the applet below.
(0.3, 0.2, 0.1, 0.0, 0.4, 0.5, 0.6, 0.7, 8.0, 1.4) with these
8 samples and no added zeros, the spectrum looks very sparse.
Increasing Np to 16 (8 zeros added) doubles the number of lines in the spectrum.
Furthur increase of Np to 128 (120 added zeros) increases the number
of lines in the spectrum by 16.
Because the DFT does not use averaging, then the magnitude of the
lines do not decrease with added zeros.
Return to main page
Return to page index
COPYRIGHT © 2007 Cuthbert Nyack.