[time-nuts] Rubidium Performance

[Bob Camp]

Hi

The short term plot on the FE's follows a straight line from 1ms out to 100 sec. No bumps close in.

Bob



On Feb 4, 2012, at 6:23 AM, EWKehren at aol.com wrote:

> John
> Thank you for your effort. It would be nice if you could confirm the 4 to 5 
> Hz dither that seems to be the loop time constant and long term aging that 
> will  influence the GPS/Rb control loop time constant setting. I did see 1 
> E-12 per  month which may be unique to that unit.
> Bert Kehren
> 
> 
> In a message dated 2/3/2012 10:19:47 P.M. Eastern Standard Time,  
> jmiles at pop.net writes:
> 
>> 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.
> 
> The overall SSB C/N ratio I'm seeing between  1 Hz - 100 kHz is pretty much
> in line with Analog Devices' data sheet, as  are the spur levels.  
> 
> --  john
> 
> 
> 
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