[ntp:questions] Re: questions on msf (via shm) clock

Helmut Wollmersdorfer helmut at wollmersdorfer.at
Thu Dec 30 13:16:59 UTC 2004


dave morgan wrote:

> I have got my MSF refclock
> working. This has raised the following questions -

> a) will its jitter figure never go below 1?

This seems to depend on
1) how long ntpd is running
2) how stable your received signal is
3) you hardware and load on it

In the first few hours after (re)start typical values are around 2, 
after some hours jitter should consolidate below 1. Mostly I watch 
values around 0.5 (see similar posting of Jonathan).

Actual value:
   remote       refid      st t when poll reach   delay   offset  jitter
=======================================================================
[...]
*SHM(0)   .SHM.            0 l  209 1024  377    0.000   -0.572   0.086
  SHM(1)   .SHM.            0 l    -   64    0    0.000    0.000 4000.00
-SHM(2)   .SHM.            0 l   60   64  277    0.000   -2.025   0.331

Note: SHM(1) is detached at the moment.

Helmut Wollmersdorfer



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