[time-nuts] ergodicity vs 1/f

Magnus Danielson magnus at rubidium.dyndns.org
Mon Dec 18 00:42:42 UTC 2017


Hi

On 12/18/2017 01:03 AM, Bob kb8tq wrote:
> You then hit the very basic fact that a “standard noise process” does not cover what real oscillators or amplifiers
> do in the field. They have a *lot* of “noise like” issues that impact their performance. Simply coming up with a model
> for this or that process is only a very basic start to modeling a real device …..

Yes, indeed.

One does not have to be very esoteric. Temperature dependence is a very 
systematic process, and we can kind of model a good part of its major 
effects, but the "noise" of the temperature variations itself is not 
easily covered and well, is a mess all in itself.

You then go downhill from there with gazillions sources of drift and 
modulations.

We can however break some of the noise properties away and model them 
and estimate their properties to some degree, so that helps get some of 
the stuff understandable enough. The tools however is often widely 
misunderstood and misused.

I just don't see how a lengthy debate on ergodicity is really helping 
when doing it in the wrong end of things.

People does not even properly separate systematic effects from noise, so 
their noise analyses becomes way of the mark and the systematic analyses 
does not have proper confidence intervals. Then the discussing the color 
of black does not help to understand the color of the orange very much.

Cheers,
Magnus



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