[time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

William H. Fite omniryx at gmail.com
Mon Mar 20 17:11:36 EDT 2017


You are talking about product design, development and optimization, not the
production of a one-off for home use. Since performance standards are
already well established, it is only necessary for the developer to test
the bench built instrument against published standards and determine if
performance is good enough to suit him. Given a sound understanding of the
role of various components in the system, it will be a great deal faster
and easier for the builder to tinker with the one-off then to go through an
extensive process of model development and verification.

I have spent a good deal of my career doing performance modeling,
verification, and validation in collaboration with other scientists and
also engineers. You describe the process correctly but I think it is
generous overkill for the topic under discussion here. Or have I missed
something in the discussion? Is the desired end result a device for
manufacture and sale? If so, then your approach is right on target.


On Monday, March 20, 2017, Attila Kinali <attila at kinali.ch
<javascript:_e(%7B%7D,'cvml','attila at kinali.ch');>> wrote:

> On Thu, 16 Mar 2017 00:06:49 -0700
> Chris Albertson <albertson.chris at gmail.com> wrote:
> > I actually did use your method.  I have a Rb and Thunderbolt, a pair
> > of freq. counters and so on.    But still I wanted to see if I could
> > build from scratch and verify proper operation and keep the budget
> > under say $50 for everything from antenna to power cord.     I think
> > it can be done but one can only verify longer term stability.
> Hmm.. doing verification of self-built (or aquired) equipment from
> scratch is a different game altogether. If you want to build things
> yourself, you first have to form a model of what disturbs your system,
> measure these parameters and verify the model against your measurements.
> Then you start building systems that exhibit different distortions,
> model these, measure and verify them. After you have built enough
> systems with different environmental characteristics, you verify
> them against eachother to make sure that your models faithully
> model reality and contain all parameters up to the error bound of the
> model.
> After a couple of decades of building and verification, you can be
> reasonably sure your GPSDO works correctly ;-)
> > (Yes you were correct a GOOD oversized XO is not sensitive to the
> > environment.  But notice the above budget.)
> 50$ for a complete GPSDO, batteries included, is quite a low price limit.
> A decent OCXO already costs 20-30$ on ebay. 100-200$ is a more realistic
> limit for a homebrew GPSDO with time-nuts like performance.
> A non-ovenized XO will not come close to time-nuts standards ;-)
>                                 Attila Kinali
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>                  -- Miss Matheson, The Diamond Age, Neil Stephenson
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William H Fite, PhD
Independent Consultant
Statistical Analysis & Research Methods

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