[time-nuts] Setting Rubidium to match GPS source

[SAIDJACK at aol.com]

In a message dated 9/28/2007 02:07:08 Pacific Daylight Time,  
hmurray at megapathdsl.net writes:

>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?



Hi HMurray,
 
depends on the GPSDO. On the Fury for example you can expect the unit to  
wander less than +-15ns back and forth over a period of 1 Day. That's a  
deviation of about 3.5E-013 or so per 24 hours.
 
This wander depends on how good the hold position is that is set inside the  
GPSDO's GPS receiver, as well as the stability of the OCXO, and the quality of 
 the GPS receiver.
 
All standard GPS receivers have problems with height:
 
We see a range of about +-2 Meters max on the height on the Motorola M12+  
receiver on different Fury units for example. The newer M12M motorola/iLotus  
receiver is slightly better than this.
 
This would lead to a worst case error of up to 12ns just due to this  antenna 
position error, slightly more than a good Cesium would wander.

Said
 
 
 



************************************** See what's new at http://www.aol.com