[time-nuts] Cs stability

Tom Van Baak tvb at LeapSecond.com
Mon Jul 16 20:21:23 EDT 2007

> After that they give you the environmental and physical
> specifications. For the hp5071 you have:
> Are the Allan deviation specs also valid for all the environmental
> range, including shock and vibration, or only for lab conditions?

The given specs are conservative (in typical HP style) but
I would guess the best ADEV numbers are only for laboratory
conditions. Someone from Agilent/Symmetricom might want
to comment on this.

> OF COMMERCIAL ATOMIC CLOCKS", Pekka Eskelinen claims to
> have measured a phase temperature coefficient of 100ns/degree
> for commercial Cs clocks in 1999.

I'll comment after I read it. But the 100ns/degree value doesn't
make sense because that's phase instead of frequency units.

Did he mean 100 ns per day per degree? Or per 200 hours,
or 2000 hours, etc. If the latter, that represents a per-degree
frequency shift of 100 ns / 2000 h = 1.3e-14 which sounds
about right to me for a cesium tempco. It also depends on the
model: the tempco of a vintage hp 5060A or hp 5061A is likely
worse than a modern 5071A, for example.

> Has any of you ever measured such a coefficient?

Yes, I'll take a look over my old data files and see what I have
on cesium. This week I just happen to be measuring the tempco
of an old Russian H-maser (about 2e-14/C). Please see:



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