Practical Zero Padding
To interpolate a uniformly sampled spectrum
,
by the factor
, we may take the length
inverse DFT, append
zeros to the time-domain data, and take
a length
DFT. If
is a power of two, then so is
and
we can use a Cooley-Tukey FFT for both steps (which is very fast):
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(3.45) |
This operation creates





In matlab, we can specify zero-padding by simply providing the optional FFT-size argument:
X = fft(x,N); % FFT size N > length(x)
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Zero-Padding to the Next Higher Power of 2
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Proof of Aliasing Theorem