[time-nuts] Returnee, interested in Lars GPSDO

[john.haine at haine-online.net]

Hello everyone, I have just re-joined the list after being on pendulum-nuts
for a while (where I still am!).  I was impelled to join as I'm thinking
about a new clock timer, I have dabbled in the past with an OCXO and one of
TVB's picPETs.  I just got some new surplus OCXOs and the thought crossed my
mind of disciplining it to GPS - why not start another project?

 

Tom directed me to a number of websites with GPSDO designs and the "Lars DIY
GPSDO" looks interesting being relatively simple and Arduino based.  One
thing about it does puzzle me though and I thought I'd seek your collective
wisdom.  It uses a 4046 PLL chip just for its RS-flipflop type phase
comparator which then drives a simple time interval comparator (TIC).  What
surprises me is that it doesn't use the 3-state phase/frequency detector -
in principle this has the benefit of automatically frequency locking.  This
is the type of PD I have used in synthesisers in the past.  Is there a
reason why the unit works this way, can anyone advise please?

 

Have a great Christmas everyone, and Happy New Year.

 

*	John Haine