[ntp:questions] Meinberg NTP Software--Time Accuracy

David Woolley david at ex.djwhome.demon.co.uk.invalid
Sat Jun 20 20:28:27 UTC 2009


W. eWatson wrote:
> 
> In some science working I'm doing, I need subsecond accuracy for
> timestamps.  I was told the s/w in the Subject will do the trick. Maybe

It's not the Meinberg NTP Software it is the University of Delaware NTP 
software, more commonly known here as the reference implementation. 
Meinberg simply wrote a Windows installer for it and compiled it.  (It 
used to be Dave Mills' NTP software, but the copyright was recently 
assigned.)

> someone has used it before. I have little to go on, but installed it
> successfully yesterday--I think. I gave it the tick.usno.navy.mil NTP 

Although it will work after a fashion, that server will be seriously 
overloaded.  In a university, your first choice should be your campus 
servers, then the univerity's ISP's.  You should not be using a stratum 
one server if you are leaf node.

> server name, and that finished the install. After
> a minute of looking at my clock, there was no change. It happened to be
> maybe 30 sec off according to my atomic clock.  What mechanism do I need

Make sure that you have the right timezone; ntpd will abort if the time 
is more than 1000 seconds out.  (NTP itself users UTC, which will be 
converted to local time by your OS.)

> to use to truly get it started? I don't think what I did showed it was
> adjusting my clock at all.

Generally at this stage you need to run ntpq and use its peers 
sub-command, then its assoc sub-command and finally run rv for each 
association id (in your case just one) in the assoc output.  Post the 
results here.
> 
> I gave it one NTP server, as above, but probably need more. It allows up
> to 9. I'm on the west coast, California.

That would be an installer restriction.  If you manually configure it, 
you can have more, although there is a limit to the number of good ones 
that it will actually use.  Four is a recommended number.  Less 
compromise the fault tolerance.
> 
> There doesn't seem like much beginner support at their web site. None?
> See download page at <http://www.meinberg.de/english/sw/ntp.htm>

The primary documentation is at http://www.ntp.org/, although that may 
reference the development version.  The installer really ought to have 
installed a directory full of html documentation, as the policy is that 
you use the documentation that accompanies the executable.
> 




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