[time-nuts] PRS-10 findings

SAIDJACK at aol.com SAIDJACK at aol.com
Wed May 30 03:10:12 EDT 2007


Hello guys,
 
some time ago we talked about curious humps in the ADEV of the SRS PRS-10  Rb 
at around 20s intervalls.
 
I think I may have more info on that (and as usually that raises more  
questions):
 
Below is a capture of the phase offset between a PRS10 1PPS  output compared 
to the Jackson-Labs Fury 1PPS output as measured with a  53132A.
 
The Fury output has been shifted by about 80ns to give a  nice phase offset 
for the 53132A to measure.
 
Besides the underlying counter noise, there clearly is a jump of  about 0.5 - 
1ns visible exactly once every 15 seconds! Indicated by  arrows.
 
Could this be the counter self-calibrating?  This is too regular to be  
co-incident.
 
Has anyone else seen this?
 
I don't see this on a scope when comparing two 1PPS's so I do think it's  the 
counter.
 
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