[time-nuts] Frequency processing scheme of HP5065 vapour rubidium standard

[Rick Karlquist]

Magnus Danielson wrote:
> There is frequency pulling even in Cesium beams. Only a few beams handles
> the
> phase error pulling by reverting the beam direction. Fountains have this
> together with doppler reduction.

In the 5071, nearly every error source has been beaten into
submission.  However, CBT phase shift is the last hold out.
Extraordinary proprietary measures are taken to make the microwave
cavity mechanically symmetrical to with tenths of thousands of
an inch, and with no systematic error.  I can't get into detail,
but you can believe no stone was left unturned.  The remaining random
error is typically a few parts in 10^13.  The systematic error
seems to be below 10^-14.

As Magnus said, the solution to this is beam reversal, however that
would be too complicated in a compact clock like the 5071.

Rick Karlquist