Fred Marshall wrote:
> "Rajan" <[email protected]> wrote in message
> news:[email protected]..
> >
> > Hi all!
> > I am a newbie to DSP. I have some basic questions. I will really
> > appreciate if someone answers them.
> >
> > 1. Is it logical to perform 1024 point FFT on a vector of size less than
> > 1024 (say 150) in MATLAB ?
> > 2. If yes, then -does MATLAB perform zero padding automatically in above
> > case or do we need to do it manually ?
> > 3. what kind of output will it give ?
>
> 1. Maybe, if that's what you want to do.
> It will take longer than computing an fft over just 150 points.
> The results will be an interpolated version of an fft that is 150 points but
> add really no new information. So, the apparent increased resolution is a
> bit illusory.

It won't add information. But there will be an increase in
the resolution of the precise frequency of a well separated
sinusoidal component, more accurately than can be done
with using just the peak bins or even quadratic interpolation.
Essentially you get a high quality interpolator of lots
of intermediate points automatically in a much longer fft.


IMHO. YMMV.
--
rhn A.T nicholson d.0.t C-o-M