[ntp:hackers] A stop-gap authenticated time service
phk at phk.freebsd.dk
Sun Nov 15 11:12:42 UTC 2015
In message <5648650F.1060502 at rubidium.dyndns.org>, Magnus Danielson writes:
>If I get the time, I might derive the various ADEVs for noise through
>PLL. Might be a useful article.
You're provably better at math than me, so I'd probably not be a very
useful reviewer, but to the extent I can assist in any way, just yell
My personal "hands-on" experience is that the P term is invaluable
for initial capture, but once you're captured, it usually just adds
high frequency noise and for tracking you are better off with a
pure I regulator.
I'm not sure if this is why, but I do note that all of the HP506x
atomic frequency standards only use an I term.
When I realized that the NTP kernel-pll's P-term noise profile was
a source of instability, I started experimenting with different
"decay" strategies for the P-term. I need to finish that and
publish the results and code.
Time, never enough of it...
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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