[time-nuts] Disciplining Rubidium
smace at intt.net
Thu Apr 24 20:47:39 EDT 2008
I ended up doing this with a LPRO-101 that I am using with the Fury a few days ago.
The unit did not loose lock, however it did cause it to drift very slowly for a few
hours. This was a 90degree turn. It also changed the airflow over the heatsink,
so I'm sure that had something to do with it as well.
This resulted in peak of +30ns of phase error over a 4 hour period.
SAIDJACK at aol.com wrote:
> Hi Antonio, Tom,
> recently I had to unplug my PRS10 Rb from GPS for about 3 days. It drifted a
> couple 100ns in that time frame.
> When I plugged the GPS 1PPS back in, I saw a significant frequency error of
> a couple of parts to the E-10 while the PRS10 was shifting the 1PPS back onto
> Pretty bad for a Rubidium I thought.
> For such a large phase error I would have expected the PRS10 to just reset
> the 1PPS rather than drift it.
> I may have to adjust the loop time constants to be more than 7 hours.
> To address your question: I would expect the PRS10 to behave in a similar
> manner when turning it upside down. It would probably take some minutes or
> longer to re-lock the OCXO to Rb, then correct the OCXO to 1PPS phase error that
> Typical OCXO errors for a turn-over test are parts in E-09, that causes a
> very significant immediate phase drift.
> Can't try it in my setup unfortunately.
> In a message dated 4/24/2008 15:28:55 Pacific Daylight Time,
> iovane at inwind.it writes:
> Why the XO in a GPS-Rb-XO version should not bear this problem?
> I understand that Rb itself shouldn't, but what about the controlled XO?
> (I have an interest in orientation sensitivity of measuring instruments).
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