[time-nuts] Setting Rubidium to match GPS source
Hal Murray
hmurray at megapathdsl.net
Fri Sep 28 09:06:25 UTC 2007
> Another question, has anyone here used an HP 3575A Gain Phase Meter
> (1Hz - 13MHz) to set their Rubidium to match the GPS sourced 10 MHz
> clock? Would that method be more accurate to line the Rubidium up
> than using a 12 digit frequency counter clocked off of the GPS?
How useful is just a scope? Trigger on one signal, look at the other, wait a
while to see if it drifts.
It's probably easier to notice changes (drift) if you look at both signals
and align them so you don't have to use delayed sweep.
I'm not sure how stable delayed sweeps are, but it should be easy to test.
Just look at the triggering signal and delay out a half cycle and see if
that's stable.
Handwave... If I can see a 1 nanosecond drift, that's 1E-9 per second. (Old
scopes aren't that good, but I said I was handwaving.) So I have to wait
1000 seconds (17 minutes) to get 1E-12.
In this context, how stable is a GPSDO? If I used a Cesium for the sync
input, how much fuzz would I see on a GPSDO output if I watched it wander
back and forth for a day?
--
These are my opinions, not necessarily my employer's. I hate spam.
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