[time-nuts] Some results of PRS10 and Trimble Resolution T

SAIDJACK at aol.com SAIDJACK at aol.com
Wed Jun 28 18:56:58 EDT 2006

HI Hmurray,
you said:
>One of Said's graphs had a minor bump at roughly 2 seconds.  I saw  another 
>graph with a small spike at 2 seconds, but I don't remember  where.

I thought these bumps were rather considerable, at about 1 to 2E-011, about  
8 - 10x what our GPS-locked OCXO's do.

>So why does that cause a bump at 2 seconds?  Why not 1 second  or 5 seconds? 
>It seems reasonable to filter out the 5 seconds, but  I can't see how to 
>filter out 1 second without also filtering out the 2  seconds.  I think I'd 
>expect a shoulder rather than a bump.   It would fall off above 2 seconds 
>blend in below 2  seconds.

My question exactly. I just talked to someone who uses SRS PRS10  Rb's, and 
apparently SRS admitted to him that the <10s ADEV is fairly  bad on the PRS10 
units (without any details).
It's exactly peaked at 2s, it's got to be something digital like the DAC  
control of the OCXO etc. Any SRS designers among this group? BTW: while I cannot  
prove it anymore, I am pretty confident the PRS10 did the same thing while  
free-running (without 1PPS input).

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