[time-nuts] Austron 2201, Tbolt, HP 3801 comparison question

Azelio Boriani azelio.boriani at screen.it
Sun Apr 8 17:22:00 UTC 2012


Basically, with the Kalman method, you end up in tuning your mathematical
model coefficients to follow exactly the OCXO; then you can do whatever you
want: drive it to have a fast lock-in, drive it for extremely low drift,
apply a forward correction to extend the holdover...

On Sun, Apr 8, 2012 at 7:27 AM, Charles P. Steinmetz <
charles_steinmetz at lavabit.com> wrote:

> Ulrich wrote:
>
>  The Smartclock in difference seems to be able to adapt regulation
>> parameters to its "measurements" of ocxo stability and long term drift.
>>
>
> I do not know any details about Smartclock, but I believe one of the
> things it does is to adjust the oscillator disciplining parameters
> (primarily the loop time constant, I suspect, but perhaps more) to allow
> 3801s to reacquire lock quickly after a holdover event (or at startup),
> then switch to parameters that reduce the deviation once it is firmly
> locked.  You have to do that manually with a Tbolt if you want both quick
> lock and best stability once locked.
>
> It may also do as you suggest -- use heuristic methods to tweak the "low
> deviation" discipline parameters -- but I do not know if that is the case
> or, if so, if it is better than Kalman filtering.
>
> Best regards,
>
> Charles
>
>
>
>
>
>
>
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