[time-nuts] Advantages & Disadvantages of the TPLL Method

WarrenS warrensjmail-one at yahoo.com
Thu Jun 17 01:29:57 EDT 2010


Charles

> I'm curious how you determined that the oscillators are being held to 
> within femtoseconds of each other.
I done  it several ways including measuring the PD output.

You seem to be missing how insignificant an 1-e6 injection locking to EFC 
gain ratio is.
I can't detail, to your satisfaction, all the hundreds of test that show no 
significant effect of so many different things.

For an independent test that may help you with things you missed see:
http://www.ke5fx.com/tpll.htm

ws

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[time-nuts] Advantages & Disadvantages of the TPLL Method
Charles P. Steinmetz charles_steinmetz at lavabit.com
Thu Jun 17 02:10:31 UTC 2010

Warren wrote:
>Charles Posted:
>
>>How much EFC is required depends, in part, on the strength of the pulling.
>>There are three varying inputs.
>
>NOT at ALL what my test have shown so I guess we do NOT agree on this.
>The point you missed, is only the EFC is changing significantly
>because of the high gain and BW.
>It insures the two Oscillators are held to within  femtoseconds of
>each other, to at least out to the e-16 at large taus.
>So other things are held constant enough that their effects are kept
>below any ref Osc effects.

Why must everything be a matter of other people missing something?  I
understand how oscillators behave with respect to injection
pulling/locking, and how that might affect the operation and accuracy
of a system such as you are using.  I myself noted that Magnus had
suggested the effect may not be significant in such a system, but
that drawing that conclusion for any particular design would require
careful experiments and, hopefully, backup by mathematical
analysis.  How is that missing anything?

>The "carefully constructed experiments", that show it works as
>advertised have been done, and the most important ones have been posted.

Forgive me if I missed something, but all I saw regarding the
relative gains of the error loop and the injection loop were (i) that
you "increased the coupling by a factor of 1000" and (ii) that you
used a variable attenuator.  If you did carefully designed
experiments, nothing I saw posted suggested it.

This is a potentially important point because some oscillators one
might want to test (or use as a reference) may be very much more
sensitive to injection locking (pulling, actually) than the ones you
are using.  Therefore, the behavior should be characterized so users
can determine whether it might affect their results.  "It didn't seem
to have any effect using the oscillators I had" is not really a very
useful characterization of the behavior.  [I do see that in a
subsequent message you asked for suggestions for further tests.]

I'm curious how you determined that the oscillators are being held to
within femtoseconds of each other.  And, how many femtoseconds?

Best regards,

Charles 





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