[time-nuts] Setting Rubidium to match GPS source

Hal Murray hmurray at megapathdsl.net
Fri Sep 28 05:06:25 EDT 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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