[time-nuts] Primary Time Standards

Jim Palfreyman jim77742 at gmail.com
Thu Jul 14 02:26:14 UTC 2011


Hi All,

I've just realised I don't understand something. Something quite basic.

Primary Standards are ones which don't have to be calibrated against others.
My understanding is that Caesium and Hydrogen masers are Primary Standards
(in our field).

Secondary Standards are calibrated against the Primary Standards. My
understanding is that Rubidium is an example of a Secondary Standard.

So I can calibrate my Rubidium clocks by adjusting the C Field. All good.

But why is it that Caesium Clocks and Hydrogen Masers have an adjustment
facility?

And what about the clocks used to determine UTC around the world? Do they
have an adjustment facility? What are they adjusted to? Wouldn't that make
them Secondary Standards?

Now I'm aware that the "average" of those clocks is UTC, so are those clocks
adjusted regularly to get closer to that average?

I'm sure someone can clear this up for me.

Regards,

Jim



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