[time-nuts] Rubidium Performance
Bob Camp
lists at rtty.us
Sun Feb 5 00:16:17 UTC 2012
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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