Re: Software PLL (SPLL)

Terry Given wrote:
> Ron N. wrote:
> > Tim Wescott wrote:
> >>Implementing a PLL in software uses the same basic theory as
> >>implementing a PLL in hardware -- you compare your synthesized signal to
> >>a reference, generate a phase difference, then servo the frequency of
> >>your synthesized signal to your reference.
...
> > Why?  Isn't a software PLL just a forward interpolator.  Why not just
> > estimate (statistical, FFT, phase vocoder or otherwise) the frequency,
> > phase, derivatives of phase, etc.; generate a forward interpolation of
> > the input reference using that information, and call that the output of
> > the PLL NCO?  Recalculate periodically (every sample if the compute
> > power is available).
...
> you would have to work quite very to match, let alone beat, the
> performance you can get from a software PLL, requiring negligible
> computational overhead.
>
> swatting flies with Howitzers often causes more problems than it solves.

If a simple feedback PLL is such a good solution, why isn't it used
more often for general frequency estimation and interpolation
problems?


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