[time-nuts] Rubidium Performance

Magnus Danielson magnus at rubidium.dyndns.org
Sat Feb 4 12:37:22 UTC 2012

On 04/02/12 04:19, John Miles wrote:
>> Someone earlier today made the point that for all the talk about the FEI
>> rubes, there hasn't been any real performance info posted.  That prodded
>> me to start an experiment I've been meaning to do for a while.  I have
>> samples of all three of the common telco Rb standards -- Efratom FRS,
>> Datum LPRO, and Fe8-5680.
>> Over the next couple of days I'll do measurement runs of each of the three
>> versus an HP-5065A laboratory Rb (for ADEV), and a Wenzel ULN (for phase
>> noise).  I'll collect long enough to get solid ADEV out to at least 1000
> second
>> tau on each unit.  I have the FRS test running now.
>> If all goes well, I'll post the results early next week.
> I'm doing some short-term runs on the ones I have around here, as well
> (FE-5680A, PRS-10, LPRO).  Will be interesting to see how close ours are.
> So far, the FE-5680A is doing well in the ADEV department, but its AD9832
> DDS chip adds some substantial noise and spurs to the 10 MHz output.  Does
> yours have that chip?  I understand that some of them didn't.

Consider that we have two basic generation of 5680A, one using the 
50,255.. MHz VCXO and one using 60 MHz + DDS VCXO. The later can then 
have a DDS output option.

So there can be three different 10 MHz qualities. It would be 
interesting to see the ADEV, TDEV and phase noise of all three.


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