[time-nuts] Time Dilation tinkering
kb8tq at n1k.org
Wed Mar 22 07:28:05 EDT 2017
In this case, the vacuum might work against you. You change the pressure outside
the package and you get a flex. Flex translates to dimensional changes. That gives you
a frequency shift. People make absolute pressure sensors this way :) Rb’s are by no
means the only frequency standard impacted by this effect. Precision OCXO’s have the
If you had enough room inside the package, you could do a “can in a can” sort of approach.
The outer vacuum sealed can flexes. The inner vacuum sealed can does not see anything.
You don’t eliminate the sensitivity this way, you do attenuate it quite a bit with each layer.
The question then becomes - is is worth the increase in size? Since the pressure sensitivity
is well below many other environmental factors …. probably not.
> On Mar 22, 2017, at 1:04 AM, jimlux <jimlux at earthlink.net> wrote:
> On 3/21/17 4:29 PM, Hal Murray wrote:
>> scmcgrath at gmail.com said:
>>> However CSAC not subject to barometric effects as Rb units are
>> Does anybody tried to measure CSAC vs pressure?
> The physics package in a CSAC is a vacuum, so it probably won't make much difference.
> But, as a practical matter, I have a system with a CSAC going through thermal vacuum testing as I write this. We'll get some test data and we can compare the frequency against GPS and a OCXO at room temp/pressure, and at various temps in vacuum.
> Remind me in 2 weeks, and I should have the data plotted.
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