Re: [time-nuts] Possible GPS Interference test - false alarm
James Flynn writes: > > I am away from experiment at moment, but what I could check remotely > indicated everything was running hot, straight and normal. > > I will check it again when I get back and put up data. > > I have not seen this before but was not running during earlier GPS > interference tests. > > I checked out the equipment when I got back to the lab and found that the time difference measuring and recording system had gone bad. It was occasionally doubling the time difference for some as yet unexplained reason. It was pure coincidence that there was a GPS interference test announced for the same time. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Possible GPS Interference test
A long, long time ago I captured a solar flare while monitoring GPS signal strength: http://febo.com/pages/gps_solar_flare/ There was a very significant drop in signal level. Unfortunately, I wasn't able to capture any phase data that corresponded to the event. John On 9/30/2015 3:15 PM, Mike Millen wrote: Would this sunspot activity have anything to do with it? http://spaceweather.com/ Mike On 30/09/2015 18:18, Tim Shoppa wrote: I went ahead and did the math based on some of your numbers. I was a little unclear on which numbers to use. -2E-10 in frequency over 5 minutes, is -60ns. 60ns is not completely unreasonable for an ionospheric delay variation over hours, but I think it would be unusual for there to be so much tumult in just 5 minutes though. (Especially when geophysical K index has been particularly calm lately.) On the other hand, -2E-10 over 3 hours, is -2 microseconds which is just huge! Do you have anything like a graph of phase difference or EFC over those 3 hours? Tim N3QE On Wed, Sep 30, 2015 at 1:54 AM, James Flynn wrote: I recorded apparent anomalous activity on the GPS signal received near Los Angeles from about 0200Z to 0500Z 30 Sept. The 1PPS received signal shifted by -2E-10 in frequency (5 minute averages). There is a notice on the GPS website about possible interference today (29 Sept) through 30 Sept in the area of 253 nm around China Lake, CA. (which includes Los Angeles) Anyone else near LA notice anything? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Possible GPS Interference test
Would this sunspot activity have anything to do with it? http://spaceweather.com/ Mike On 30/09/2015 18:18, Tim Shoppa wrote: I went ahead and did the math based on some of your numbers. I was a little unclear on which numbers to use. -2E-10 in frequency over 5 minutes, is -60ns. 60ns is not completely unreasonable for an ionospheric delay variation over hours, but I think it would be unusual for there to be so much tumult in just 5 minutes though. (Especially when geophysical K index has been particularly calm lately.) On the other hand, -2E-10 over 3 hours, is -2 microseconds which is just huge! Do you have anything like a graph of phase difference or EFC over those 3 hours? Tim N3QE On Wed, Sep 30, 2015 at 1:54 AM, James Flynn wrote: I recorded apparent anomalous activity on the GPS signal received near Los Angeles from about 0200Z to 0500Z 30 Sept. The 1PPS received signal shifted by -2E-10 in frequency (5 minute averages). There is a notice on the GPS website about possible interference today (29 Sept) through 30 Sept in the area of 253 nm around China Lake, CA. (which includes Los Angeles) Anyone else near LA notice anything? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Possible GPS Interference test
I went ahead and did the math based on some of your numbers. I was a little unclear on which numbers to use. -2E-10 in frequency over 5 minutes, is -60ns. 60ns is not completely unreasonable for an ionospheric delay variation over hours, but I think it would be unusual for there to be so much tumult in just 5 minutes though. (Especially when geophysical K index has been particularly calm lately.) On the other hand, -2E-10 over 3 hours, is -2 microseconds which is just huge! Do you have anything like a graph of phase difference or EFC over those 3 hours? Tim N3QE On Wed, Sep 30, 2015 at 1:54 AM, James Flynn wrote: > I recorded apparent anomalous activity on the GPS signal received near Los > Angeles from about 0200Z to 0500Z 30 Sept. The 1PPS received signal > shifted by -2E-10 in frequency (5 minute averages). > > There is a notice on the GPS website about possible interference today (29 > Sept) through 30 Sept in the area of 253 nm around China Lake, CA. (which > includes Los Angeles) > > Anyone else near LA notice anything? > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Possible GPS Interference test
Hal Murray writes: > > What sort of gear did that? Was it a GPSDO that went into holdover? Has it > gone into holdover at other times? > I am running a proof of constant test bed comparing time/transfer method using another medium with simple GPS time receiver. I have a disciplined double oven crystal oscillator that is generating the 1PPS signal for comparison. GPS receiver is a Navman T-60 in position hold mode (timing). I will see missing pulse errors if the time signal is invalid. I was not seeing those except at very end. The anomalous behavior lasted on and off (mostly on) until 1330Z Sept 30 (this morning). There were large timing errors in the last ten minutes or so and then signal seemed to settle down to normal. I am away from experiment at moment, but what I could check remotely indicated everything was running hot, straight and normal. I will check it again when I get back and put up data. I have not seen this before but was not running during earlier GPS interference tests. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Possible GPS Interference test
I've been in Seattle when a AWACS has been at Boeing and GPS was non functional when it was on the ground this took out multiple GPS platforms the on board unit in the rental my portable unit plus the one in the iPhone Content by Scott Typos by Siri On Sep 30, 2015, at 6:02 AM, Hal Murray wrote: >> Anyone else near LA notice anything? > > I'm in Silicon Valley. I got wiped out by tests from China Lake a while ago. > I didn't see anything this time. > > Anybody know anything about the directionality of the testing? > > >> The 1PPS received signal shifted by -2E-10 in frequency (5 minute >> averages). > > What sort of gear did that? Was it a GPSDO that went into holdover? Has it > gone into holdover at other times? > > > > -- > These are my opinions. I hate spam. > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Possible GPS Interference test
> Anyone else near LA notice anything? I'm in Silicon Valley. I got wiped out by tests from China Lake a while ago. I didn't see anything this time. Anybody know anything about the directionality of the testing? > The 1PPS received signal shifted by -2E-10 in frequency (5 minute > averages). What sort of gear did that? Was it a GPSDO that went into holdover? Has it gone into holdover at other times? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Possible GPS Interference test
I recorded apparent anomalous activity on the GPS signal received near Los Angeles from about 0200Z to 0500Z 30 Sept. The 1PPS received signal shifted by -2E-10 in frequency (5 minute averages). There is a notice on the GPS website about possible interference today (29 Sept) through 30 Sept in the area of 253 nm around China Lake, CA. (which includes Los Angeles) Anyone else near LA notice anything? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
