[time-nuts] HP5065A reversing the C-field ?

[Poul-Henning Kamp]

In physical terms, the direction the C-field does not matter in a
atomic frequency standard, it just has to be of constant magnitude.

The ambient magnetic fields adds to the C-field, most notably the
geomagnetic field, and any (strong) nearby DC currents.

Some of the "telecom" rubidiums reverses the C-field periodically,
presumably to average out any stray magnetic fields which get past
their puny, if any, mu-metal shielding.

The HP5065A is stationary and shielded, so the stray fields should
be small and almost constant, and implementing periodc reversal would
likely convert it from a frequency normal to geomagnetometer.

But if one reversed the C-field, by swapping the wires to the solenoid,
and measured the frequency-shift, wouldn't that give a measurement of
how good the magnetic shield works ?

Has anybody ever tried this ?

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