I am an extreme novice in this field but my understanding is that the C-Field adjustments on the CS standards (5061A, 5061B that I am familiar with) allow for insuring that the appropriate energy state transition of the CS Ion is chosen as the 'reference' for the standard, something that can be accomplished without 'calibrating' against another device.
The standard 5061A and 5061B provide a standard set of frequencies (5 MHz, 1 MHz, and 0.1 MHz for both the 5061A and 5061B and also 10 MHz for the 5061B). I have never measured them against each other but I suspect their phase will vary while their frequencies will be exact. It is hard to imagine that all CS ions are 'in phase' world wide. The 5061A and 5061B both offer clock options that provide an indication of time in an Hr:Min:Sec format as well as 1 PPS output. There is also an adjustment on these clocks to allow the 1 PPS to be synchronized with an external 1 PPS such that the clocks can all be set to the same time +/- a small error on the 'phase' of the 1 PPS. If my understanding is incorrect, I would greatly appreciate being corrected/educated. Joe -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jim Palfreyman Sent: Wednesday, July 13, 2011 9:26 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Primary Time Standards 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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
