[time-nuts] Comparing Reference Accuracy
not.again at btinternet.com
Mon May 26 16:41:31 EDT 2008
On Fri, 23 May 2008 09:26:43 +1200, you wrote:
>The errors of the various GPSDOs cannot be determined without access to
>a primary standard.
Has anyone here tried to squeeze extra medium term performance out of
a rubidium by controlling (or compensating for) environmental factors
like temperature and pressure? Not having a decent reference for
testing GPSDOs was one thing that made me want to see what could be
done, although I'd been wanting to try it for a long time anyway.
I recently got around to testing an LPRO against GPS, and the
stability was still a fairly useful 1E-13 at 1 day. It was in a
temperature controlled housing, and had an analogue pressure sensor
connected up to it to adjust the c-field to compensate for air
pressure changes - not a perfect setup, but as an experiment it was
I'm not suggesting that it would be as good as a primary standard, but
it could be useful in some circumstances, either stand-alone or
steered to GPS.
The only paper I came accross which deals specifically with this is a
rather short one where FE5650A's were tested: "The Effects of Ambient
Temperature Fluctuations on the Long-Term Frequency Stability of a
Miniature Rubidium Atomic Frequency Standard"
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