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GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

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Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#31

Post by beambot »

joering2 wrote: post #29
lisper wrote: post #26

It is worth noting that there are two different ways to attack GPS: jamming and spoofing. Jamming is when you broadcast a noise signal at the GPS frequency, which prevents affected receivers from receiving the GPS signal. The result is that the GPS doesn't know where it is. Spoofing is when you send out a fake GPS signal that appears genuine but has the wrong timing. The result is that the GPS thinks it knows where i…

This is what keeps my awake at night sometimes... that one of US drones flying over Afghanistan will be eventually fooled into thinking the target it has to drop a bomb on is actually somewhere else over the Europe.

Depending on who you believe, that GPS spoofing has already been used for military purposes: https://en.m.wikipedia.org/wiki/Iran–U.S._RQ-170_incident

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#32

Post by jof »

joering2 wrote: post #29
lisper wrote: post #26

It is worth noting that there are two different ways to attack GPS: jamming and spoofing. Jamming is when you broadcast a noise signal at the GPS frequency, which prevents affected receivers from receiving the GPS signal. The result is that the GPS doesn't know where it is. Spoofing is when you send out a fake GPS signal that appears genuine but has the wrong timing. The result is that the GPS thinks it knows where i…

This is what keeps my awake at night sometimes... that one of US drones flying over Afghanistan will be eventually fooled into thinking the target it has to drop a bomb on is actually somewhere else over the Europe.

The GPS P(Y) and Military codes exist to (hopefully) prevent spoofing.

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#33

Post by lawl »

Reason077 wrote: post #4
otp124 wrote: post #2

I don’t see the assumption of the cause in the PDF (difficult to read on this tiny mobile device). Could it be iron ore or something else affecting the magnetic fields? Does this happen elsewhere on earth?

Seems unlikely to be a natural phenomenon, considering it's never been noticed before. Could be the Russians are up to something? Jamming GPS signals would be a significant strategic advantage in war time.

Could just as well be the US. When selective availability was disabled they said they will come up with something new to deny hostile forces accurate GPS. [0]

> Develop measures to prevent the hostile use of GPS and its augmentations to ensure that the United States retains a military advantage without unduly disrupting or degrading civilian uses.

GPS only being jammed at higher altitudes, but not on the ground fits the above pretty well imo. We don't know how this jamming would affect US military GPS usage, but it's not impossible to think that it doesn't.

[0] https://www.faa.gov/about/office_org/headquarters_offices/at...

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#34

Post by philsnow »

johansch wrote: post #3

I experienced a very odd GPS failures about a week later (September 24) in south-eastern Sweden. At one point I was driving for about an hour (in quite isolated areas - around https://www.google.com/maps/@58.0381615,16.2094966,13.37z ) without my iphone being able to get a gps fix. It's never happened before, or since. The phone was fixed to the car's front window with plenty of sight towards the sky. I rebooted the…

Cell phones don't use only GPS signals, they use "aGPS" which uses signals from cell towers to make the GPS calculations easier / faster. It's so effective in environments that the overwhelming majority of people spend the overwhelming majority of their time in that I think manufacturers don't include the very best GPS antenna, since they don't need to.

You say you were in remote areas, how was your cell signal during the time you couldn't get a GPS fix?

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#35

Post by anovikov »

jof wrote: post #32
joering2 wrote: post #29

Earlier quoted context omitted.

This is what keeps my awake at night sometimes... that one of US drones flying over Afghanistan will be eventually fooled into thinking the target it has to drop a bomb on is actually somewhere else over the Europe.

The GPS P(Y) and Military codes exist to (hopefully) prevent spoofing.

They aren't. A spoofer doesn't need to know what the signal means/be able to decrypt it. Just retransmit signal received from a different place at higher power. Only way to distinguish it from a real one is timing, but that requires an atomic clock, which is $15,000 and too expensive for most applications.

But, military grade GPS receivers use virtual beam forming to achieve a very high attenuation of spoofing signal so they are extremely hard to spoof, they always get the real signal as stronger.

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#36

Post by lisper »

anovikov wrote: post #35
jof wrote: post #32

Earlier quoted context omitted.

The GPS P(Y) and Military codes exist to (hopefully) prevent spoofing.

They aren't. A spoofer doesn't need to know what the signal means/be able to decrypt it. Just retransmit signal received from a different place at higher power. Only way to distinguish it from a real one is timing, but that requires an atomic clock, which is $15,000 and too expensive for most applications. But, military grade GPS receivers use virtual beam forming to achieve a very high attenuation of spoofing signal…

Yeah, I'm not terribly worried about military drones. But as a civilian pilot I worry a lot about whether the non-military-grade GPS in my airplane is telling me the truth.

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#37

Post by danbruc »

Animats wrote: post #28
danbruc wrote: post #6

Earlier quoted context omitted.

But after a few tens of meters in the air we see a noise signal. [...] The noise signal is on GPS L1 (1575.42 MHz) with 1 MHz bandwidth, see Figure 3-5. So the signal is jammed by something sending a noise signal around the L1 frequency, whether intentionally or not.

Look at the screenshot from the spectrum analyzer. That's a very specific signal, uniform in power, centered on the L1 frequency, and contained to a 1MHz bandwidth. That's intentional, not some random event.

It surly looks like intentional jamming but I did not want to draw any conclusions that are not in the source. It certainly does not look like any random event but it could still be unintentional, e.g. someone just forgot to turn of his GPS jammer or accidentally broadcasts on that frequency, but that is admittedly not the most plausible explanation. I am also not sure how big a deal the whole thing is, I would assume that GPS jamming is not too uncommon to protect potential high profile target.

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#38

Post by jschwartzi »

lisper wrote: post #36
anovikov wrote: post #35

Earlier quoted context omitted.

They aren't. A spoofer doesn't need to know what the signal means/be able to decrypt it. Just retransmit signal received from a different place at higher power. Only way to distinguish it from a real one is timing, but that requires an atomic clock, which is $15,000 and too expensive for most applications. But, military grade GPS receivers use virtual beam forming to achieve a very high attenuation of spoofing signal…

Yeah, I'm not terribly worried about military drones. But as a civilian pilot I worry a lot about whether the non-military-grade GPS in my airplane is telling me the truth.

Hopefully GPS isn't your sole source of information.

When I'm out scrambling I make sure that I carry multiple navigational aids so that I can cross-check. I also pay attention to terrain features before trips as well as during so that I can locate myself, or in the worst case make my way to the handrails that I've identified on my map.

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#39

Post by heartbreak »

anovikov wrote: post #35
jof wrote: post #32

Earlier quoted context omitted.

The GPS P(Y) and Military codes exist to (hopefully) prevent spoofing.

They aren't. A spoofer doesn't need to know what the signal means/be able to decrypt it. Just retransmit signal received from a different place at higher power. Only way to distinguish it from a real one is timing, but that requires an atomic clock, which is $15,000 and too expensive for most applications. But, military grade GPS receivers use virtual beam forming to achieve a very high attenuation of spoofing signal…

Yeah I doubt the engineers forgot about replay attacks when designing their military GPS.

Re: GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf]

#40

Post by lisper »

jschwartzi wrote: post #38
lisper wrote: post #36

Earlier quoted context omitted.

Yeah, I'm not terribly worried about military drones. But as a civilian pilot I worry a lot about whether the non-military-grade GPS in my airplane is telling me the truth.

Hopefully GPS isn't your sole source of information. When I'm out scrambling I make sure that I carry multiple navigational aids so that I can cross-check. I also pay attention to terrain features before trips as well as during so that I can locate myself, or in the worst case make my way to the handrails that I've identified on my map.

> Hopefully GPS isn't your sole source of information.

Nowadays, in modern airplanes, it often is your only source of positional information when you're in instrument conditions (which is, of course, when it matters most).

> I carry multiple navigational aids

Yeah? Like what?

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