[time-nuts] Update on my Arduino GPSDO / NTP server - going atomic

Andrew Rodland andrew at cleverdomain.org
Sat Sep 6 21:14:45 EDT 2014

On Fri, Sep 5, 2014 at 3:07 PM, Andrew Rodland <andrew at cleverdomain.org> wrote:
> 1. Should I try using the analog EFC to zero out the amount of
> correction I ask the X72's DDS for? Could reduce jitter in the
> timebase, could just add noise. I suppose I can test this one easily
> enough.

Update on this: well, it works just fine, and I have a usable driver
in my code that integrates the digital correction and pushes it to 0
by adjusting a DAC connected to the X72's EFC.

But, reading the X72 manual a little closer it mentions that the
analog EFC is "sampled" and has a "resolution" that happens to be
identical to the resolution available using the digital commands. So,
most likely, this is no C-field adjust at all, but another way of
controlling the DDS, provided for LPRO compatibility and analog
designs. So there's no possible gain for me in doing indirectly what I
can do directly more easily.


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