On Wed, Apr 21, 2010 at 1:51 AM, Arnold Krille <arnold@xxxxxxxxxxxxx> wrote:
Wouldn't that only apply to a signal *at* Nyquist, which by definition is not covered by the sampling theorem? How would it even be possible for a signal at, say, 22.04 kHz be phase-aligned to the sampling clock?
This is a pretty bold claim, and contradicts Nyquist and other literature. Do you have a citation for the claim that frequencies "as low as a quarter of the sampling-rate" are damaged by sampling?The highest frequency possible to reproduce -with correct amplitude- is half
the sampling-rate _only_ if the phase is aligned to the sampling-clock so that
minima/maxima of the sinus are correctly sampled. If its out of phase, the
amplitude is not reproduced correctly.
Wouldn't that only apply to a signal *at* Nyquist, which by definition is not covered by the sampling theorem? How would it even be possible for a signal at, say, 22.04 kHz be phase-aligned to the sampling clock?
It is easy to understand that this correlation between phase and correct
amplitude also affects frequencies below half the sampling-rate. Might be as
low as quarter of the sampling-rate, which in case of the CD is 11kHz. Below
that you will have more then four samples to reproduce the sinus wave.
That is in fact another reason to do the recording, mixing and mastering in
more then 44kHz...
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