[time-nuts] GPSDO control loops and correcting quantizationerror

Bob Camp lists at rtty.us
Sun Sep 16 19:05:58 UTC 2012


Hi

The basic assumption is that this is a lab gizmo and that there is indeed a static adev (or very low frequency phase noise) plot for the OCXO (or Rb).  The other assumption is that this plot is quite good (say decreasing or flat to >10,000 seconds). 

IF that's all true, then the "running condition" is the pll loop frequency / time constant / cross over that does not degrade that adev (or phase noise) plot with noise from the GPS. 

Bob

On Sep 16, 2012, at 1:56 PM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> In message <ACD158CA-D76C-4A8B-B77D-4FA691D0B50B at rtty.us>, Bob Camp writes:
> 
>> 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.
> 
> But what is "running condition" ?
> 
> I see my PLL adjust to thermal conditions during summer (A/C) and
> winter (heating) and even to GPS constellation changes...
> 
> -- 
> 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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