GPS jamming or spoofing on a wide scale is definitely a viable attack! As another commenter noted well, making everyone appear at exactly the same location would be nigh-impossible, though.
GPS receivers will look for the 'strongest' PRN signal in the noise, so broadcasting louder than the (incredibly weak!) C/A signal is a valid way to jam or spoof GPS. It is, however, generally illegal for civilians.
GPS receivers operating with good practice do tend to try to mitigate this sort of attack, by (for example) ignoring signals with a too-high power level. It's a bit of a cat and mouse game, and there are academic papers exploring each side.
Lastly, GPS receivers also need to deal with interference from GPS itself! If GPS signals bounce off surfaces before reaching the receiver, the receiver might see two sets of GPS signals: one that arrived directly, and one that was scattered off a surface and arrives a bit later. This is called ‘multipath interference’, and part of what goes into making GPS receivers work well is mitigating multipath interference.
> making everyone appear at exactly the same location would be nigh-impossible, though.
I don't think this is actually the case. In a spoofing scenario, all of the rogue signals would typically be generated by a single terrestrial station. The time of flight of all of the generated signals will be the same, so all that matters is the position solution reflected in the transmitted signals, as the fundamental principle of GPS based on TOF is no longer in play. So I'd think that in a typical spoofing scenario, all receivers thinking they're in more or less an identical location is what you'd expect.
It might be possible in a borderline case for the receiver to receive some spoofed signals and some real signals simultaneously, in which case you'd expect weird results, but I think you'd definitely see a correlation around the position being broadcast by the spoofer.
Just to be a little clearer, jamming and spoofing are the not the same thing. Jamming obfuscates a signal, usually through noise. Spoofing impersonates the signal.
This may be theoretically possible but is, in reality, practically impossible.
Embedded within the GPS signal is the ephemeris data which, among other things, includes each satellite's location in space.
Receivers calculate position by calculating the difference between the time a signal was received and the time stamp encoded in the signal itself.
By analyzing the signals from a minimum of four satellites (one for each dimension in time and space), a receiver calculates where it is.
To spoof all phones on Earth, you would need to trick each receiver individually. Since receivers are passive, they don't identify themselves, and there would be no way to target each individual receiver, making them think they're somewhere they're not.
1. Jamming is obfuscating a signal, usually by creating a lot of noise that makes the real signal hard to find. Spoofing is impersonating a signal.
You can blast out fake data, but depending on what you mean by "large area" and a "point", I don't think what youre suggesting is possible. To trick GPS receivers you end up broadcasting fake signals from multiple GPS satellites, so receivers in different areas will be processing it differently and come up with different coordinates.
So does this means that in recent days there wasn't GPS jamming but GPS satalites were broadcasting fake signals? In south Turkey people were appearing to be in Beirut airport.
No, the fact that all of these ships show the same false location strongly suggests that they are being spoofed from a single terrestrial source; this effect is not practical to achieve by modifying the signals transmitted by the satellites, even if the US wanted to for some reason.
I'm having a hard time telling from the article - are the ships' GPSes actually reporting that they're at the airport? Or is the disconnect happening somewhere between GPS and AIS (eg they're intentionally transmitting bad location data- it's been common-ish in the past for ships to do this when doing something naughty (blockade running or illegal fishing) and given what's going on in the region I can see the value of keeping your location obscure for safety
On March 30 a friend of mine messaged me. He wrote me that his phone and his wife's phone were appearing to be in Beirut airport. But they were at home in Mersin, Turkey. On April 2 he wrote me that his phone was showing his location as Mersin correctly. During that period this map was showing GPS anomalies in Easternn Mediterranean Sea https://www.flightradar24.com/data/gps-jamming it looks like there is still anomalies.
I think it was due to Israel's some kind of defense measure against Iran.
It’s not really that simple. Most phones these days do not rely solely on GPS for location data. Many use a combination of WiFi, Bluetooth, dead reckoning, GPS, Galileo, GLONASS, QZSS, and BeiDou.
Even if a couple of these signals are degraded, wrong, or missing, most phones will come up with a relatively accurate location using the remaining data.
