[ntp:questions] GPS and the December 5/6 Solar Flare

John Ackermann N8UR jra at febo.com
Fri Apr 6 15:06:24 UTC 2007

This receiver wasn't hooked to an NTP server, so I don't have direct
correlation.  However, the number of satellites tracked didn't
noticeably drop, and the signal strength was still in a usable range, so
I doubt there would have been much impact on timekeeping.

Also, my GPS-refclocked NTP server was running from a GPS-disciplined
oscillator which is specifically designed to "ride out" GPS signal
dropouts, so I don't think the NTP data from that unit would yield much


Ryan Malayter wrote:
> On Apr 5, 6:51 pm, j... at febo.com (John Ackermann N8UR) wrote:
>> For what it's worth, the attached plot shows what I saw.  This
>> was the only significant signal strength anomaly in over one year of
>> data capture.
> Did the drop in strength cause any anomalies with ntpd? That is, was
> sync with PPS "lost" during the signal drop? Do you have any loopstats
> graphs that correspond to the same time period?
> Very interesting stuff... I just realized that all of the stratum-1s I
> was using for my organization have GPS as the source. I've
> subsitituted a stratum-1 that uses ACTS instead to one of my local ntp
> servers, but I am wondering if that is enough so handle a significant
> GPS interruption. I have four local NTP servers serving two locations
> with good connectivity, and each as at least one unique upstream
> server.
> As others have mentioned, though, this may be somewhat pointless: an
> event that distrupts GPS for a long period is likely to have so many
> other ill effects that I won't care much about my company's
> network ;-). In building our disaster recovery plans, we had a bunch
> of scenarios to which the answer was "we cease operations", because no
> employee could be expected to worry about the company in the event of
> truly major disaster.
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