
GPS signal disturbed at altitudes above 2000-3000 feet over Norway [pdf] - 3eto
https://rntfnd.org/wp-content/uploads/Norway-Comms-Auth-Report-GPS-Jamming-Sept-2017.pdf
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lisper
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 it is, but it's wrong. Spoofing
is more difficult -- and far more serious -- than jamming. What is reported
here appears to be (an attempt at) jamming, but spoofing attacks have also
been reported in the past.

[https://www.schneier.com/blog/archives/2017/09/gps_spoofing_...](https://www.schneier.com/blog/archives/2017/09/gps_spoofing_at.html)

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joering2
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.

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

~~~
anovikov
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.

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

~~~
throwaway2048
They arn't very easy to avoid, say you capture the signal from a satellite
that is not visible to the receiver, or being jammed out, unless you have an
extremely high precision clock, you can just delay the signal rebroadcast and
spoof away.

~~~
derefr
Everything involved in GPS requires all the nodes (both the senders and the
receivers) to have "extremely high precision clocks."

That's the whole idea, really: you, the receiver, have a clock, and a map of
where the various GPS satellites will be around the earth at given times. You
"hear" the current time announced from three satellites (along with their
station IDs), and compare those times to your clock to figure out the flight
time of the data, and thus the distance to the satellites. Then you take the
satellites' known positions on the map at the current time, plus the flight
times, and triangulate your own position.

If one of the three times you've received is a "lie", then its relative time
will correspond to an impossible distance for that GPS satellite to be
relative to where the map says it should be (e.g. over the horizon relative to
you), and relative to where the _other_ two satellites that you heard from
are. (Theoretically you _could_ receive such signals—using reflectors, like
HAMs do—but GPS discounts this possibility and just considers it invalid
data.)

~~~
ianburrell
GPS receivers do not have clocks. Atomic clocks are expensive and large; there
is no way you get one every device.

Only the satellites have atomic clocks. The receiver get the time from the
satellites. It basically compares the time delay between the satellites to
determine position and time.

~~~
derefr
I didn't say they have _atomic_ clocks. They do have clocks, though. Like most
computers do. And they are high-precision, and are low-drift _enough_ to
predict the locations of satellites as long as they have been re-synchronized
within the last few days or so.

Which, as you say, also happens by just observing the time signatures from the
satellites. You need four visible satellites to determine your own time,
though, whereas you only need three for position, so time isn't re-synched as
often as position is calculated. The internal clock in the receiver allows the
receiver to carry on tracking with only three time sources for a while.

But, to be clear on the topic of the parent discussion: I believe JDAM
missiles (the ones that actually do use GPS) _do_ have either an atomic clock
source [more recently], or [formerly] have at least a high-precision monotonic
clock source with low drift that is synchronized at point-of-launch by the
clock on the bomber, which also has an HPC that was calibrated at _its_ launch
by a real atomic clock. They don't need to rely on external time-sync.

And modern ICBMs? Well, unless your jammer/spoofer can keep up with them, or
is itself a satellite, you're only going to be able to affect them when
they're on their descent course and making final adjustments. And, like this
article says ([https://www.technologyreview.com/s/423363/how-cruise-
missile...](https://www.technologyreview.com/s/423363/how-cruise-missiles-
would-beat-gps-jammers-in-libya/)), ICBMs have redundant aiming systems based
on computer vision applied to either visual-spectrum or radar-based sensors.

~~~
scrumper
Your final point conflates icbms with cruise missiles - very different things.
I don’t believe icbms use TERCOM or visual matching.

~~~
anovikov
Nor they use GPS for that matter. ICBMs are completely inertial.

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johansch
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](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 device twice but it didn't help.

Our natural instinct here is to blame the russians for these kinds of things.
At this time our biggest military exercise since the 90s was taking place in
this region, with a lot of US involvement:
[https://en.wikipedia.org/wiki/Aurora_17](https://en.wikipedia.org/wiki/Aurora_17)

(One random theory: the russians were trying out some kind of remote,
localized target GPS jamming tech. The GPS outage stopped once I got closer to
the largest city in the region (150k people).

Additional rationale: If they unleashed GPS jamming signals that made hundreds
of thousands of people lose GPS it would probably have made news. By
localizing it to just affecting a couple of hundred people in isolated areas
they would avoid that kind of mess.)

~~~
netsharc
I would assume the US/NATO also jams GPS/use some sort of scrambler for the
unencrypted signal to have some military advantage...

~~~
Cyph0n
I think the US military uses a different GPS signal that provides higher
accuracy positioning.

~~~
manarth
The feature is called "Selective Availability", and has been disabled since
May 2000.

[https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...](https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Selective_availability)

~~~
Cyph0n
So are you saying that the US military does not have a higher accuracy
positioning system? I highly doubt that.

~~~
manarth
There are well-known ways to improve GPS accuracy, such as dGPS [1], inertial
guidance, and beam-riding [2].

I think it unlikely that the US military has a secret second constellation of
GPS-like satellites, operating on an undetectable secret frequency. Firstly,
it would be difficult to launch and operate such a constellation in secret,
and secondly, because augmenting the GPS data with independent, secondary
sources operating with a different approach provides more redundancy and is
proven technique for increasing accuracy.

The capability to limit accuracy in the satellite signal already existed – the
fact that it was shut off is a strong signal that the perceived benefit is no
longer important.

[1]
[https://en.wikipedia.org/wiki/Differential_GPS](https://en.wikipedia.org/wiki/Differential_GPS)
[2]
[https://en.wikipedia.org/wiki/Beam_riding](https://en.wikipedia.org/wiki/Beam_riding)

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cesis
There's was also some cellphone outage reported in Baltic

[https://www.washingtonpost.com/world/europe/latvias-
cellphon...](https://www.washingtonpost.com/world/europe/latvias-cellphones-
stopped-working-russias-war-games-may-be-to-
blame/2017/10/05/449162d4-a9d3-11e7-9a98-07140d2eed02_story.html?utm_term=.9a11a75a4095)

------
otp124
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?

~~~
Reason077
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.

~~~
gsich
It's bad if you relly on one and only system. As there is NAVSTAR GPS, Glonass
and Galileo you'll have to jam your own system too.

~~~
jhayward
GPS and Galileo use the same frequency for their public service. Jamming one
gets them both.

Glonass is a couple hundred megaherz away from GPS L1.

~~~
gsich
So there is no reason NOT to support Glonass.

~~~
burntrelish1273
Except the Russians run and control it and may consider opportunities to
weaponize it offensively against unsuspecting Western users.

The best bet is to use as many positing systems as possible in order to
prevent attacks narrowly targeting one positioning system.

~~~
gsich
The same can be said to NAVSTAR GPS. The only system which is not primarly
built for military uses is Galileo.

Yes, that's what I am saying. Don't rely on one system. Using more also
increases accuracy.

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cozzyd
Would be interesting to see if this shows up in GPS occultation data.

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UncleEntity
There was massive solar flare activity in September which may (or may not)
have something to do with this.

~~~
ISL
It is the rare natural phenomenon that can make 1 MHz-wide bandstopped white
noise, centered exactly on a human-chosen navigational frequency of import.

