[time-nuts] Different Thunderbolt versions

[SAIDJACK at aol.com]

Hi Bruce,
 
the PRS-10 datasheet is pretty smart in not showing the data below 10s  
through, it would make their >10s performance not shine as much. There  certainly 
could not be any measurement reason for not showing <10s  ADEV.
 
As someone has mentioned, they also used a very bad GPS receiver as a  
reference which makes their ADEV look spectacular against the GPS  ADEV.
 
It is possible that this plot is pre-SA-disabled, but then should they not  
update their website with more recent data? I guess one could also argue that  
even if you use a bad GPS the unit will still generate a good ADEV above 10s  
intervals and that is what they are trying to show. It's all in the  
specmanship.
 
bye,
Said
 
 
In a message dated 2/25/2009 23:04:54 Pacific Standard Time,  
bruce.griffiths at xtra.co.nz writes:

That  isnt a great advantage in this application given that the
contribution of  the ionosphere to the VLBI receiver output signal phase
noise is around  8E-11 @ 10s at 50MHz.
Typically in VLBI integration times op up to 10,000  seconds or more are
used. Integration times shorter than 100 sec are not  usually of  much
interest.

Bruce