[ntp:questions] Offset Average (Normal)?

Alby VA albyva at empire.org
Tue Mar 13 17:26:37 UTC 2012


On Mar 13, 12:05 pm, David Lord <sn... at lordynet.org> wrote:
> Alby VA wrote:
> > On Mar 13, 9:59 am, David Lord <sn... at lordynet.org> wrote:
> >> That seems to be working ok.
>
> >> The NMEA sentences aren't being reported because PPS is being
> >> used to condition the system clock.
>
> >> David
>
> >  Okay. My whole understanding of NTP and Clocks is now
> > becoming clearer. My apologies, I'm still a n00b.
>
> >  So what you are saying is the GPS time via the SureGPS
> > device is now being ignored and the time of my machine is
> > now being held in check by the PPS signal? If yes, does
> > that mean seeing "oGPS_NMEA" is better than seeing
> > "*GPS_NMEA"?
>
> >  Since I can't find any docs on deciphering the ntpq output,
> > I'm trying to understand what the symbols next to each
> > entry represent. Some I've found, but maybe you could
> > correct me:
>
> > o = ???
> > * = ??? (My Assumption: preferred time server)
> > x = ??? (My Assumption: False Tick - Bad Time)
> > + = ??? (My Assumption: Next Best Server for Time)
> > - = ??? (My Assumption: Ignore this useless server)
>
> > ** Sorry for all the questions. Just trying to educate myself on being
> > a
> > time master too. :)
>
> That code indicates PPS is conditioning the system clock.
>
> I don't know why your previous ntp.conf wasn't working.
> Sometimes when there are problems I've found there are two
> instances of ntpd running so if I have a problem one check
> is with "ps ax | grep ntpd" and "cat /var/db/ntp/ntpd.drif"
>
> David




Thanks David and Ron. That weblink was just what I needed.
It looks like I've now got everything working correctly.
At last check the offset was: 0.000001427 vs.
 -0.015715484 24/hrs earlier from the peerstats info.


 I think I might tweek down David's GetNTPus.pl
script even more than 100us (previously: 12000us)
since everything is now hovering around 1us - 2us.

URL: http://godzilla.empire.org




godzilla# ntpq -crv -p -c cv -c rv
assID=0 status=041d leap_none, sync_uhf_clock, 1 event, event_13,
version="ntpd 4.2.6p5 at 1.2349-o Mon Feb 20 22:00:33 UTC 2012 (1)",
processor="amd64", system="FreeBSD/9.0-RELEASE", leap=00, stratum=1,
precision=-19, rootdelay=0.000, rootdisp=0.326, refid=PPS,
reftime=d30a00e8.df8798ed  Tue, Mar 13 2012 13:22:48.873,
clock=d30a00ef.04857ba3  Tue, Mar 13 2012 13:22:55.017, peer=51346,
tc=4, mintc=3, offset=0.001, frequency=-24.616, sys_jitter=0.002,
clk_jitter=0.002, clk_wander=0.005
assID=0 status=0000 clk_okay, last_clk_okay,
device="NMEA GPS Clock",
timecode="$GPGGA,172254.000,3903.1206,N,07729.1027,W,
1,6,1.69,101.6,M,-33.4,M,,*6D",
poll=1296, noreply=0, badformat=0, baddata=0, fudgetime1=0.000,
stratum=0, refid=PPS, flags=5
assID=0 status=041d leap_none, sync_uhf_clock, 1 event, event_13,
version="ntpd 4.2.6p5 at 1.2349-o Mon Feb 20 22:00:33 UTC 2012 (1)",
processor="amd64", system="FreeBSD/9.0-RELEASE", leap=00, stratum=1,
precision=-19, rootdelay=0.000, rootdisp=0.326, refid=PPS,
reftime=d30a00e8.df8798ed  Tue, Mar 13 2012 13:22:48.873,
clock=d30a00ef.04bd8f7a  Tue, Mar 13 2012 13:22:55.018, peer=51346,
tc=4, mintc=3, offset=0.001, frequency=-24.616, sys_jitter=0.002,
clk_jitter=0.002, clk_wander=0.005
     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
+utcnist2.colora .ACTS.           1 u   49   64  377   55.288
2.518   0.554
-ntp.alaska.edu  .GPS.            1 u   30   64  377  113.212
-0.411   5.802
-tick.usask.ca   .GPS.            1 u   53   64  377   96.018
-8.027   2.205
-cronos.cenam.mx .GPS.            1 u   98   64  376  125.096
17.962  19.106
*ntp1.usno.navy. .USNO.           1 u   44   64  377   22.951
3.035   8.905
+time-a.nist.gov .ACTS.           1 u   51   64  375   13.411
3.588  34.419
oGPS_NMEA(0)     .PPS.            0 l    7   16  377    0.000
0.001   0.002
godzilla#







More information about the questions mailing list