[time-nuts] Low-Cost Rubidium Performance

[Bob Camp]

Hi

If you look at all of the phase noise plots, the noise (ignore the spurs) gets very similar between the units below 20 to 30 Hz. They all seem to be locking their VCXO up to the RB resonance at roughly the same point and it's Q / noise is taking over below this region. If you are using a classical multi step multiply to microwaves, that's still well above the point you would start rejecting the noise from your low frequency reference in the low frequency to ~ 100 MHz step. 

Bob


On Feb 9, 2012, at 4:58 AM, John Miles wrote:

>> Important note: there's known to be a lot of variability among these
>> units, so my sample size of one or two each isn't a guarantee that your
>> unit will perform similarly.
> 
> Neat.  Your FE-5680 noise plots look just like the ones I took.   Seems
> clear that this particular variant was meant for timing or calibration work
> rather than communications.
> 
>> Next step is to do some longer-term stability measurements (out to 100K
>> seconds).  You may see that data in a month or so.
> 
> How's the environment where you're running the long-term test?  Any exposure
> to HVAC circulation or any other sources of changing temperature?  I've
> taken a few longer-term plots with the LPRO, but I've always suspected it
> could do better if it were actively temperature-stabilized, or at least
> shielded from room air currents.  
> 
> New page with my short-term plots here: http://www.ke5fx.com/rb.htm
> 
> (These include HP 5065A, LPRO-101, SRS PRS10, and FE-5680A)
> 
> -- john, KE5FX
> 
> 
> 
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