); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] In a cesium beam standard, the only systematic offset from the unperturbed state is the C-field, and its offset can be determined and removed very accurately by Zeeman techniques. Many other possible offsets are servoed to virtually zero (less than 10^-14). The servoing is all done using cesium physics, without reference to any other frequency source.
Rubidium and hydrogen use gas cells. These have frequencies that depend on many things, especially pressure and temperature of the gas. In Rb standards, there are also optical offsets. It is also possible to make a cesium gas cell standard. It will behave like a Rb standard in terms of being a secondary standard. When we used to build 5071A's, we simply built them and they came up on frequency. There is no "setting" procedure. We could have built them in a "clean room" containing no clocks, GPS, or other cesium standards, etc. without difficulty. The very first one we ever built was taken to NIST to be checked and was within a couple of parts in 10^13. Rb frequency standards will come up on different frequencies depending on differences in the gas mixture and pressure in the various cells, etc. You always have to have a cesium standard to set them to frequency. One possible point of confusion is that the 5071A allows the user to introduce a controllable offset as a convenience. This is done with a synthesizer that was available anyway. This has nothing to do with "setting" the 5071A to the correct frequency. I hope this clears up any confusion. Rick Karlquist N6RK Member 5071A design team and 10816A Rubidium design team _______________________________________________ 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.
