[time-nuts] Moving GPSDO
attila at kinali.ch
Tue Oct 18 05:11:37 EDT 2016
On Mon, 17 Oct 2016 16:44:55 +0200
Attila Kinali <attila at kinali.ch> wrote:
> 3) Rb vapor standards have very low acceleration effects. As Dave
> said, the control loop will kill most of the effects inside the
> loop frequency. The loop frequency is relatively fast, in the
> order of couple of 100Hz to a couple of 10kHz, depending on the
> exact build of the Rb standard and what type of crystal they used.
> Contrary to what he says, there are no acceleration dependent
> diffusion effects. The vapor cell is is heated and the gas atoms
> in there are pretty fast, any acceleration of them will be negligible
> compared to what they do upon collision. The relativistic red shift due
> to acceleration is way too low to measure (much lower than the intrinsic
> noise). The only mechanical effect that is possible, is bending of
> the microwave cavity or the parts inside. But given that the cavity
> is several mm thick aluminium and everything is mounted rigidly,
> I very much doubt that there is any significant effect.
Correction: I just had a look at the LPRFS specs. It lists a 2g tip-over
sensitivity of 2*10^-10/g on the worst axis. I have no idea what's going
on there. No other of the Rb vapor standards of which I have the spec
at hand list any acceleration sensitivity.
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