[time-nuts] Caveats on Allan Deviation with ultra stable oscillators
phk at phk.freebsd.dk
Fri May 30 22:24:03 UTC 2014
In message <email@example.com>, "John Miles" writes:
>people have even reported similar behavior with cesium standards, although I
>don't see how that could happen. There aren't supposed to be any
>first-order temperature effects in a CBT, and I'd think that any lower-order
>effects would be way beneath the tube's flicker floor...)
One important trick in this area:
Always locate your DUTs physically orthogonal to each other.
Almost none of our DUTs have 3 axis of symmetry, and therefore
most environmental effects are not symmetric with respect to
I noticed this by accident comparing three "identical" OCXO's
because I had put one of them in a different orientation than
the other two: The environmental noise were much larger between
that one and the two other, than between the two co-aligned
I'm not entirely sure this is relevant for Rb/Cs/H, their environmentals
should be attenuated enough for it to not matter.
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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