[time-nuts] Time Dilation tinkering

Michael Wouters michaeljwouters at gmail.com
Tue Mar 21 16:40:44 EDT 2017


These are less stable than a rubidium eg tau=10e-11 at 1000s and monthly
ageing of 9e-10.
The price of these has gone up  too- they're now about US5000.

Cheers
Michael

On Wed, 22 Mar 2017 at 7:03 am, Scott McGrath <scmcgrath at gmail.com> wrote:

> 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
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of no
> > use without that foundation.
> >                 -- Miss Matheson, The Diamond Age, Neil Stephenson
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