[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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