[time-nuts] TPLL secret reveled

Tom Van Baak tvb at LeapSecond.com
Thu Jun 10 22:27:30 UTC 2010

> Fact #1) the TPLL uses Freq not phase,

Warren, can you please clarify. From what I can see it actually
uses a Minicircuits phase detector, right? That suggests what is
being observed is a phase difference between the DUT and the
REF, not a frequency difference.

That analog phase measurement is then filtered and amplified
into a pre-calibrated EFC correction to the REF which over a
short time reduces the phase difference as seen by the phase
detector. The digital stream comes from an ADC is connected
to the EFC.

So what does it mean to say "TPLL uses Freq not phase"? It
looks to me like it uses both.


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