[ntp:questions] Atomized NMEA using second numbering from other server
Dave Hart
hart at ntp.org
Fri Oct 14 16:53:37 UTC 2011
2011/10/14 Miguel Gonçalves <mail at miguelgoncalves.com>:
> Hi all!
>
> This is the billboard from one of my servers (ntp 4.2.6p3):
>
> tock# ntpq -p
> remote refid st t when poll reach delay offset jitter
> ==============================================================================
> oGPS_NMEA(0) .GPS. 0 l 6 16 377 0.000 -0.001 0.003
> +ntp-p1.obspm.fr .TS-3. 1 u 6 64 377 44.396 0.860 1.342
> +ptbtime1.ptb.de .PTB. 1 u 34 64 377 68.039 2.179 0.698
> -ntp1.oma.be .PPS. 1 u 43 64 377 52.612 4.312 0.819
> *canon.inria.fr .GPSi. 1 u 60 64 377 44.358 1.177 0.902
> -ntp1.nl.uu.net .PPS. 1 u 49 64 377 57.991 3.550 0.989
>
> Does the tally code * mean that NTP is getting the seconds from
> canon.inria.fr? The NMEA driver is configured as prefer.
>
> On another server (4.2.7p222) I am getting
>
> tock# ntpq -p tick
> remote refid st t when poll reach delay offset jitter
> ==============================================================================
> *GPS_NMEA(0) .GPS. 0 l 13 16 377 0.000 0.561 1.374
> oPPS(0) .PPS. 0 l 12 16 377 0.000 -0.001 0.004
> +ntp-p1.obspm.fr .TS-3. 1 u 30 64 377 44.128 1.085 0.779
> +ptbtime1.ptb.de .PTB. 1 u 18 64 377 65.281 0.412 11.300
> -ntp1.oma.be .PPS. 1 u 26 64 377 52.953 4.699 3.274
> +canon.inria.fr .GPSi. 1 u 26 64 377 44.764 1.471 1.906
> -ntp1.nl.uu.net .PPS. 1 u 27 64 377 56.525 2.892 0.987
>
> Here ntp is getting the seconds from GPS_NMEA.
>
> What happens when the first server looses it's connection to the Internet?
The first one is configured with NMEA with PPS enabled. The second
one is configured with NMEA with PPS disabled, and also with the
PPS/atom driver. I have a system configured similarly to your first,
with the only refclock source NMEA with PPS enabled, running
4.2.7p214. It shows the 'o' pps peer tally code for NMEA, and has no
association with the * sys peer tally code -- the LAN sources are all
marked with + or space tally codes. Are you using "prefer" in the
ntp.conf for the first one?
I would not expect NMEA + PPS of being capable of using anything but
NMEA to number the seconds. As a result, though, I'd never think to
use prefer in that configuration, so I don't have experience with NMEA
+ PPS while prefer is set on another association.
Cheers,
Dave Hart
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