[time-nuts] using Fury GPSDO with Rb

SAIDJACK at aol.com SAIDJACK at aol.com
Mon Apr 7 13:41:38 EDT 2008


Hello Scott,
 
that's great news!
 
A Phase correction of 0.5 means the unit will only try to correct for  
long-term UTC offsets with very little "force" on the Rb, and it may take quite  a 
long time to get the phase error to 0ns.
 
But once you are around 0ns as in your case, the Rb is so good that it  won't 
need much of "convincing" (read: error correction via EFC voltage changes)  
by the Fury to stay on phase/frequency.
 
Also, if it keeps it locked well, then you may try to increase the EFC  
Damping to say 80 - 120 to reduce the control noise further. This increases  loop 
phase-lag, so if overdone then the loop may start to become unstable.
 
Said
 
 
In a message dated 4/7/2008 07:06:00 Pacific Daylight Time, smace at intt.net  
writes:

atom  FRS-A

DAC GAIN: 5000.00
EFC SCALE: 0.50
EFC DAMPING: 25
OCXO  SLOPE: POSITIVE
PHASE CORRECTION: 0.500000

I think the FRS-A is  adjustable from +-1.2e-9.

So far it seems to keep it within +-3ns from  GPS.

Scott





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