[time-nuts] Time Dilation tinkering
scmcgrath at gmail.com
Tue Mar 21 15:51:41 EDT 2017
Or perhaps use the Symmetricom CSAC ...
Relatively expensive but might work
> On Mar 21, 2017, at 8:08 AM, Attila Kinali <attila at kinali.ch> wrote:
> On Tue, 21 Mar 2017 13:38:51 +1100
> Hugh Blemings <hugh at blemings.org> wrote:
>> This got me to wondering if a Rubidium based standard might do the trick
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> As TvB wrote, a single one will not do the trick. You will need
> a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to 1e-13
> somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
> of about 3-4e-14 (unless our friends here improved on this already).
> There will be a few things that you will need to do, if you want to go
> with Rubidiums:
> 1) Stabilize or compensate for environmental effects (temperature, air pressure)
> 2) Build ensembles of Rb clocks.
> The former is to prevent the ADEV from "turning upwards" again and
> keep the Rb's as stable as possible as long as possible. I have no
> experience how much this helps, but I suspect, with the correct modeling
> that you could get the ADEV to be flat up to a day, maybe even two.
> You will have to include aging and drift of the cell itself in the model.
> This also means that you will have your Rbs running for a few weeks/months
> prior to any measurement so that the aging settles down a bit.
> The ensemble is to get the ADEV down. Averaging of clocks with the same
> noise decreases the ADEV by the square root of the number of clocks used.
> If you are close to the ADEV you need, the averaging will help you getting
> it further down. Unfortunately, getting from 1e-13 down to 1e-14 is
> impractical as you'd need 100 clocks to average over.... But a factor
> of 2 to 3 should be possible.
> Alternatively, you can ask Oscilloquartz whether they let you borrow
> two of their new OSA3300 for a publicity stunt :-)
> Attila Kinali
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