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

WarrenS warrensjmail-one at yahoo.com
Wed Jun 16 00:52:42 EDT 2010


Charles Posted:

>  when dealing with measurement accuracy in the hundreds or tens of ppt, 
> this needs to be verified by
>the results of carefully constructed experiments and hopefully also 
>supported by mathematical analysis.

No argument, on that part.
The "carefully constructed experiments", that show it works as advertised 
have been done, and the most important ones have been posted.
(unless you mean the experiments must be done by you)
Still waiting for someone to do the "mathematical analysis".

>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.

But no mater who is correct, It does work, which is the more important thing 
at this stage.

ws

***************
time-nuts] Advantages & Disadvantages of the TPLL Method
Charles P. Steinmetz charles_steinmetz at lavabit.com
Wed Jun 16 03:45:03 UTC 2010

Warren wrote:

>Charles posted:
>>but the locked frequency will be different from both oscillators'
>>free-running frequency and
>>the EFC will not correctly indicate the test oscillator deviation
>>because it isn't the only control input in the system.
>
>Good point and No argument  (except for the deviation part)
>Because the EFC is the only control input THAT IS VARYING.

No, it's not.  The strength with which each oscillator pulls on the
other also varies as the equilibrium frequency (the result of all
three recursive control inputs) moves around relative to the two
instantaneous free-running frequencies.  How much EFC is required
depends, in part, on the strength of the pulling.  There are three
varying inputs.

Magnus suggested that the effect of injection locking may be enough
smaller than the EFC input that it has little practical
significance.  That may be so, but when dealing with measurement
accuracy in the hundreds or tens ot ppt, this needs to be verified by
the results of carefully constructed experiments and hopefully also
supported by mathematical analysis.

Best regards,

Charles 





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