[time-nuts] NCOCXO anyone?

Bob Camp kb8tq at n1k.org
Thu Jul 21 20:22:03 EDT 2016


> On Jul 21, 2016, at 7:17 PM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> --------
> In message <4763643485B04450A76F7C04BA8CFB63 at pc52>, "Tom Van Baak" writes:
>> There are highly-prized commercial instruments that do this. But
>> no amateur has tried yet.
> It would be more precise to say that no amateur has been willing to
> talk about their results yet.
> I personally know several have tried and failed at various levels
> of performance.
> My own personal experience, both analog and VHDL, is that there is
> a particularly long and noisy way from theory to practice in this
> space.
> The one thing I have *not* tried, and the only one I think has any
> realistic chances, is to use a DDS chip which has a phase modulation
> register.

If you go the DDS route, it really needs a post filter to make it “fly right”. The narrower the
filter, the better it gets. Pretty quickly you are into an ovenized filter.  Is that better or worse
than an ovenized phase modulator? Not at all clear.


> That should get you to a nanosecond without too much trouble.
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.
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