[time-nuts] GPSDO Question

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Sep 2 19:28:52 EDT 2007

GandalfG8 at aol.com wrote:
> --------------------
> Perhaps it depends on how you define a "good" approach.
> If you're looking for the very best you can get then it probably  isn't, but 
> I don't recall that being claimed in the first place.
> However, one of the attractions has to be the simplicity of the  circuit and 
> the fact that something offering reasonable performance can be  knocked up 
> very quickly.
> Without the divider and buffers, the circuit proposed by Bertrand  Zauhar, 
> VE2ZAZ, in his QEX article reduces to just three ICs.
> It may not be optimum but it must be a strong contender for the best  you can 
> get for very little effort.
> The Idaho State University version is reported on their web page for  the 
> project as having been checked over a 13 day period, by the Idaho National 
> Laboratories Calibration  Lab, and found to be accurate to 1.2x10^-10.
> I  don't think that's too bad for a fun project that could probably  be put 
> together in an evening, even for one guilty of causing such  amusement and/or 
> distress:-)
> regards
> Nigel

A well designed phase lock loop system can also be reduced to a small
number of parts that can be assembled in a few hours so this isn't a
useful criterion.
As long as it is well understood that its a "fun" project and it doesn't
achieve the highest performance possible for a small outlay then thats fine.

The major problem is that most of the originators of these designs do
not say that the design is far from optimum, which leads the uninitiated
to blindly follow not realising they can do much better.
If one is just interested in constructing the best frequency standard
possible for a given outlay this isnt the way to do it.


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