[PD] Combat aliasing!

[Charles Henry]

On Thu, Apr 1, 2010 at 11:11 AM, Matteo Sisti Sette
<matteosistisette at gmail.com> wrote:
> Matteo Sisti Sette escribió:

> Oh no, maybe not.
> I read your explanation more carefully and of course, the non-perfectness of
> the interpolation process (i.e. its non-zero frequency response in the stop
> band) is responsible for the persistence of attenuated copies of the
> original spectrum at multiples of the original sampling rate, which then
> appear aliased into the passband when the signal is sampled again at a
> different rate.
>
>
> This is what's going on when discontinuities in the interpolated signal
> cause noise at high frequencies, isn't it?

Yes, that's my interpretation and explanation of it.  It works out
nice and linear in the spectral domain *if* we can make that
intermediate step with the Dirac-delta comb which copies the spectrum.
 Then, *all* the deviations in the reconstructed signal come from the
places where the spectrum does not match the ideal response.