Re: Software PLL (SPLL)

Ken Smith wrote:
> In article <1139427882.792589.126890@f14g2000cwb.googlegroups.com>,
> Ron N. <rhnlogic@yahoo.com> 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).
>
> Now fit that FFT into a PIC.

The OP specified a 200 MHz DSP.  Why add a PIC in addition to the
DSP?  And if he knows something about the signal, there might be
more computationally efficient statistical estimators than some FFT
frames.


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