[time-nuts] Holdover recovery
Magnus Danielson
magnus at rubidium.dyndns.org
Mon Apr 4 15:28:32 EDT 2016
Hi Hal,
On 04/04/2016 05:39 AM, Hal Murray wrote:
>
> Has anybody studied what happens when a GPSDO comes out of holdover? Has
> anybody seen any specs? I don't think I have.
>
> I think you have a choice of quick recovery for time or frequency, but you
> can't get both.
>
> Suppose your setup has been in holdover for a while. The frequency is
> slightly off. The time offset of the PPS pulse will be the integral of the
> frequency offset.
>
> What happens when you come out of holdover? If you fix the frequency, the
> PPS will stay off.
>
> Suppose the PPS has drifted by 1 ns. If you correct that in 1 second, the
> frequency will need to be off by 1E9 during that second.
The RAI laboratory in Torino have made such tests and published
measurements and recommendations. For a long time it was only available
in italian, but there is now an english version available.
Cheers,
Magnus
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