[time-nuts] GPSDO control loops and correcting quantizationerror

[Bob Camp]

Hi

The time constant can indeed be changed dynamically, that's what is often done.

The purpose of my examples was to keep things simple and look at the "running condition" of the loop rather than it's performance while it settles down.

Bob

On Sep 16, 2012, at 9:49 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> In message <CE93652A-1DA6-48E3-9883-D7616AC24A78 at rtty.us>, Bob Camp writes:
> 
> Bob,
> 
> There's one thing makes me scratch my head here:  Why do you keep
> arguing like the timeconstant cannot be changed dynamically ?
> 
> I use a very aggresive timeconstants initially, to quickly get the
> phase offset under control, and then I ramp up the timeconstant in
> order to reduce phase noise of the GPS, until I hit something which
> looks like the "Allan-intercept" (as Dave Mills calls it).
> 
> It' won't take long time for us to agree that the timeconstant
> is a tradeoff between phase and frequency error, but just because
> it is called a "timeconstant" doesn't mean we cannot change it.
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.
> 
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