[ntp:questions] One last release candidate (in name only) and a new -stable

David J Taylor david-taylor at blueyonder.delete-this-bit.and-this-part.co.uk.invalid
Sun Dec 13 08:21:19 UTC 2009

"G8KBV" <g8kbv at nospam-uko2.co.uk> wrote in message 
news:MPG.258e12bfc938897b989681 at news.demon.co.uk...
> Hi David..
> OK on all that (4800 bd etc)  I too at the moment run NTPD etc on a
> "lightly loaded" machine.  P4 1G 512Meg, not a lot else running other
> than the Win 2k system.  & I've got the reg' edited according to the
> location of the serialpps-ppsapi-provider.dll OK too.
> Have to say, that even just as a intermediary, the time keeping
> performance of the system as a whole with a local ntp server, is vastly
> superior than letting it all sync to external servers via the web.  I
> guess the time keeping algorithms in NTPD are somewhat more effecitve
> than those in Faros itself.
> All the best, hope to have more good news soon.
> Dave Baxter.

That's good news, Dave.  You can be sure that the kernel-mode 
serialpps.sys is working and connected if the ntpq -p display includes a 

  oPPS(1)          .PPS.

in addition to the basic serial GPS/PPS line:

  *GPS_NMEA(1)     .GPS.

It's a bit misleading because the GPS/PPS driver /does/ include the 
PPS-over-DCD support, just at user-mode rather than kernel mode which is 
supplied by the serialpps.sys.

One thing you can do for local systems is to poll them more frequently (an 
unfriendly act with public Internet systems) and fix the polling rather 
than let it automatically become less frequent.  This reduces the offset 
but may increase jitter slightly, but may be what you need if the 
closeness to UTC is important.  I have my LAN-synced systems set to poll 
the local stratum-1 server at fixed 32-second intervals, and the remote 
"last-chance" Internet servers at the normal variable 64-1024s interval. 
IIRC you need 4.2.5 or later to have this mixed interval polling (so 4.2.6 
and 4.2.7 should work as well).

I've heard the kernel-mode/PPS support also described as the "Atom" 
driver, although I think that refers to some better filtering.  Perhaps 
someone could clarify that.


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