[time-nuts] fast switching quiet synthesizer

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Oct 7 17:26:04 EDT 2014


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In message <20141007200046.02AA9406060 at ip-64-139-1-69.sjc.megapath.net>, Hal Mu
rray writes:

>Timing on Ethernet is as good as RS-232 if you have a point to point link 
>rather than a huge network full of crappy software.

That is a "truth" with an almost uncountable number of footnotes...

If we're only talking about timing in 99% of the cases, then yes, but
that last one percent will make you tear your hair out.

We did 20 microsecond jitter on 10GE for the ESO ELT adaptive optics
prototype, and that was seriously pushing things near the edge.

Five microseconds is trivially possible with a good $20 RS232 cable.

-- 
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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