[time-nuts] Question for my new GPSDO

[Jim Harman]

On Mon, Oct 14, 2019 at 12:09 PM Tom Van Baak <tvb at leapsecond.com> wrote:

> ...
> One other comment, do read the archive time nuts postings and blog
> entries by Nick Sayer. He did a nice work with an affordable, not
> extremely high-end but open source, GPSDO and that would be useful
> background reading for you.
>
> /tvb
>

Tobias,

I suggest you also review the GPSDO design by Lars Walenius described here
https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/


which is the basis for Nick Sayer's design. Lars has unfortunately passed
away, but I have worked extensively with his hardware and software and have
made some improvements which I would be happy to share with you off list if
you are interested.

Also if you are interested in pursuing a PWM based DAC, I suggest you
review this article
https://www.edn.com/design/analog/4460665/Fast-PWM-DAC-has-no-ripple
which describes a sample and hold technique for reducing the output noise
of a PWM DAC. The article also has references to other PWM noise reducing
techniques.

--Jim Harman