General > General Technical Chat

How an Atomic Clock Really Works, Zeeman Alignment

(1/3) > >>

BrianHG:
How an Atomic Clock Really Works, Round 2: Zeeman Alignment....

Holly Sh!t, even after over 20 minutes of 2 separate free running cesium clock's 5MHz outputs keep dead perfect relative phase.  Are even 2 separate rubidium 10Mhz references that good?  (Answered below thanks to EEVB member 'ejeffrey')


MathWizard:
And I complain about the cost of a good DMM or scope. Lab equipment like AC's cost a fortune.

So how good are the electronics in it ? What sort of tolerances do the component's have ? I wonder about the calibration and maintenance. Do they replace stuff every so many months or years like airplane parts ?

BrianHG:
Do any members here at EEVBlog own 2 rubidium 10Mhz references.
I would like to see the 2 10MHz clocks superimposed on a 2 channel scope to see if they keep perfect phase and for how long.
(Maybe I should have originally posted this thread in the TEA sub-forum.)

Kleinstein:
I think they do show the superposition of the 2 atomic clocks, giving a rather boring static picture. Even with one of them not locked (so just the OCXO running) the picture is still relatively stable.
A Rubidium clock should be more stable than even a good OCXO and the superposition should thus be also stable to the normal observer (no time laps).
One can see the slight shift in frequency with the C-field (during demagnetization), but still not that much.

Besides the cesium tube and a good OCXO there should be not be many components that are that special. As cost was not a real concern there may be a few hermetic wet tantalums that now cost a small fortune, but they should not be essential, just more common some 50 years ago.  Normally there should be no need to replace things regularly - maybe a few more normal electrolytic capacitors if they are inside an ovenized part. Much of the cost is in the developement and adjustment / operation instructions divided by only a small number of systems build. The Cs tube has a limited, but still quite long lifetime.

BrianHG:

--- Quote from: Kleinstein on November 19, 2022, 05:10:07 pm ---I think they do show the superposition of the 2 atomic clocks, giving a rather boring static picture. Even with one of them not locked (so just the OCXO running) the picture is still relatively stable.

--- End quote ---

Once both clocks were tuned and aligned, at 36:10 in the video, the 2 clocks were dead stable.
All the earlier scope shots were either GPS or comparing with the second not-yet-tuned clock.

I just wanted to see if comparing those 2 of those ebay Rubidium clock modules would keep their relative phase after an hour on the 10MHz out.  We have enough TEA members here that someone may be able to make the measurement.

The Cesium clocks, if kept at the same height above the ground, should keep relative phase for how long?
We got to be talking something like months to years if they were accurate enough to measure Einstein's when one was placed on a 747 flight back and forth to measure if the time dilation effect was real.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod