[time-nuts] Allan variance of Thunderbolt

Tom Van Baak tvb at LeapSecond.com
Fri Jul 11 15:03:21 EDT 2008


> Hello,
> 
> a question regarding the Allan Deviation of the Thunderbolt. 
> 
> the curve at
> <http://www.leapsecond.com/pages/gpsdo/>
> gives a deviation of 1.5e-12 at tau=1s
> 
> whereas from the Trimble datasheet:
> <http://trl.trimble.com/docushare/dsweb/Get/Document-10015/> 
> at tau=1s, the deviation is 9e-10  ... 
> 
> Is the data-sheet a worse-case scenario?
> 
> Regards,
> Patrick

All the Thunderbolts I've tested for the TAPR group buy have been
in the 1 or 2 or 3 parts in 10^12th at tau 1 s. Very consistent.

Right, the plot in the Trimble data sheet looks orders of magnitude
worse. It is possible the Trimble measurement system that made
the plot did not have sufficient resolution at low tau. But it is also
possible that the model we got in the surplus deal is some kind of
special high-end version of the model shown on the old data sheet.

It's hard to know for sure. Somewhere in the FAQ I note you should
ignore the plots in the Trimble data sheet.

/tvb




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