Raspberry Pi NTP config with fudge factors

[Gary E. Miller]

Yo Frank!

On Thu, 5 May 2016 18:53:42 -0400
Frank Nicholas <frank at nicholasfamilycentral.com> wrote:

> This is the “/etc/ntp.conf” I used when I ran my NTP server on a
> Raspberry Pi with the Adafruit breakout board (same as current hat).
> I list it because of the “fudge” line.  This was commonly accepted as
> the proper fudge settings, especially for time2 - 0.350:

I use the 28 refclock, you the 20.

I think for our purposes time1 and time2 are the same?  Basically the
NMEA fudge.

I use a time1 of 0.480 for my Ultimate GPS HAT.  Just about in the
middle of my 30 to 70 milliSec jitter.

> explains # these settings
> # Slightly modified, but credit to:
> # Paul Kennedy @
> (http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=1970&start=80)
> server 127.127.20.0 mode 17 minpoll 3 iburst true prefer

I find a short poll leads to a more unstable result.  Have you tried
a longer poll?

Mode 17 is 9600?  Up that if you can.

> # pool.ntp.org maps to about 1000 low-stratum NTP servers.  Your
> server will # pick a different set every time it starts up.  Please
> consider joining the # pool: <http://www.pool.ntp.org/join.html>
> server 0.debian.pool.ntp.org iburst
> server 1.debian.pool.ntp.org iburst
> server 2.debian.pool.ntp.org iburst
> server 3.debian.pool.ntp.org iburst

You'll do better if you hand pick some close chimers.  There is some
bad shit in the pool, and you may be using something from Singapore
or Bangalore.  If you must pool, at least use a US pool.  Like:

server 0.us.pool.ntp.org iburst
server 1.us.pool.ntp.org iburst
server 2.us.pool.ntp.org iburst
server 3.us.pool.ntp.org iburst

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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