[time-nuts] Advantages & Disadvantages of the TPLL Method
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Tue Jun 15 23:45:03 EDT 2010
>>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
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.
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