[ntp:questions] GPS and the December 5/6 Solar Flare
Danny Mayer
mayer at ntp.isc.org
Sat Apr 7 03:40:42 UTC 2007
Eugen COCA wrote:
> I made a test with the following configuration file:
>
> server 127.127.20.1 minpoll 6 maxpoll 6 prefer
> fudge 127.127.20.1 flag3 0 time1 0.000 refid GPS
>
> server 127.127.22.1 minpoll 4 maxpoll 4 prefer
> fudge 127.127.22.1 flag3 1 time1 0.000 refid PPS
>
> (the lines are in this order in the file)
>
> All other servers are with the "noselect" keyword in their lines.
>
> After 67 hours I obtained the following result:
>
> ntp1.usv.ro
>
> ntpq> pe
> remote refid st t when poll reach delay
> offset jitter
> ==============================================================================
> GPS_NMEA(1) .GPS. 0 l 67h 64 0 0.000
> 0.000 0.004
> ptbtime1.ptb.de .PTB. 1 u 181 256 377 56.661
> -0.200 0.639
> ntps1-1.cs.tu-b .PPS. 1 u 211 256 37 56.950
> 0.857 0.040
> ntp-p1.obspm.fr .1PPS. 1 u 177 256 377 56.803
> -0.315 6.425
> gps-2.mit.edu .GPS. 1 u 229 256 377 133.582
> 2.334 0.335
> oPPS(1) .PPS. 0 l 5 16 377 0.000
> -0.001 0.004
> ntp2.usv.ro .PPS. 1 u 42 64 377 0.193
> 0.001 0.007
> ntp3.usv.ro .PPS. 1 u 50 64 377 0.238
> 0.004 0.007
> ptbtime2.ptb.de .PTB. 1 u 142 256 377 56.393
> 1.514 0.465
> gps-1.mit.edu .GPS. 1 u 195 256 377 132.778
> 2.054 0.305
>
> The system has a GPS 18LVC receiver and a PRS-10 Rubidium Frequency
> Standard conditioning the PPS signal from the GPS receiver. During the
> test the GPS power was cut off and the only source of sync was the PPS
> signal. ntp2.usv.ro and ntp3.usv.ro are in the same network and where
> synchronized with the GPS signal during this test.
You should drop the MIT servers. They are so far away network-wise it
does you no good. Also it looks like you are too far way from the ones
in Germany and France for them to be useful either. If you need
additional servers you need to choose closer ones.
Danny
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