Re: Nyquist and the Complex-Real FFT

On Nov 28, 10:50 pm, dbd <d...@xxxxxxxx> wrote:
....
The signal should be prefiltered to a bandpass that
is much narrower than the Nyquist limit.

hmmmm. the thing i was thinking about was "merely" using an N/2
complex-in, complex-out DFT to perform an N-point DFT with real input
and where the output only contains half of the conjugate symmetric
output that you would get with a regular N-point DFT. now, to do the
"untangling", you would need an addition N/4 twiddle factors that the
N/2 point complex DFT did not use (but a regular N-point *does* use),
but there was no restriction of the bandwidth or frequency content of
the input data. the only restriction was that the imaginary part of
each sample is assumed zero (and not granted any space).

r b-j
.