Scott Burris wrote:
Murray Greenman wrote:
4. They are a handy adjunct to the GPSDO. Use the latter to calibrate
the former, and then you've a reference even if GPS is unavailable. The
Rb units also have very good short-term stability.
So, how would you go about calibrating your Rubidium against your GPSDO?
Presumably you would wait until your GPSDO has not gone into holdover
for some
"good" amount of time, whatever that would be.
Then my way would be to use the GPSDO as the external frequency
reference to
either my Racal-Dana 1998 or HP5328A, apply the rubidium as input, and
adjust
the C field for 10.00000* Mhz.
But I'm sure that's not the time-nuts way of doing this. :-) So what's
the right way?
Use the time-interval mode of the counters, log the time-interval over
time and adjust the C field until the long-term drift in time interval
between the reference and the oscillator cancels out.
Requires some divide-down thing, like the TADD-2 divide-box. Use the 100
kHz output when comparing to the PPS signal of say a Thunderbolt or
whatever is available.
Cheers,
Magnus
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