[time-nuts] Time-Nutters-- Adding Rubidium to a Thunderbolt...?

[Matthias Welwarsky]

On Montag, 2. März 2020 18:32:44 CET Skip Withrow wrote:
[...]
> The Thunderbolt DAC steps in 10uV steps IIRC.  And it steps its DAC
> voltage every second.  With GPS signals jumping around you can still
> (will) end up with poorer short term performance than if the Rb was
> left to its own devices.  Hint, let the Thunderbolt do its thing with
> the Rb, but use Lady Heather and disable disciplining when making
> measurements/comparisons.

The LPRO has a pulling range of just 4ppm at the external C-Field input (0-5V 
swing). 10µV steps over 6V should be, like 19 bits or so? That should give at 
least 7e-15 resolution for the DAC.

With a reasonably stable PPS from a timing receiver, just looking at the DAC 
movements, it should not be a problem to have a MDEV of 1e-14'ish for tau=1s. 
The LPRO itself probably has a MDEV of somewhere between 1e-11 to 1e-10 at 
tau=1s, so the GPSDO is not going to cause a lot of disturbance. Some, yes. 
The undisturbed Rb will always be better short-term than the disciplined one. 
But not an awful lot.

BR,
Matthias

> 
> Regards,
> Skip Withrow
> 
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