[time-nuts] Low-Cost Rubidium Performance

Mike S mikes at flatsurface.com
Fri Feb 10 02:03:43 UTC 2012


On 2/9/12 4:51 AM, WarrenS wrote:
 > Indeed,
 > ADEV is for random freq variation not easily measured by other means.
 > Temperature fluctuations do not cause random freq changes and the
 > temperature's effect should be removed if one wants accurate long term
 > ADEV numbers.

Why? Unless the unit is spec'd for use only at a constant temperature, 
temperature variations are something it needs to deal with, and should 
be included in any measurement of how good it is. In what way is 
temperature variability special, that it shouldn't be included in ADEV 
measurements, but all other contributors to variability should be? 
Certainly, there may be a large non-random component to temperature 
(diurnal, annual, in many environments), but there's also a significant 
part which is random - should you somehow correct for one, but not the 
other?

Shouldn't one expect the ADEV be better for a double oven OCXO than for 
a bare crystal?

The only issue I see is it may make fair comparison difficult, unless 
units are compared under identical conditions.




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