Is it possible to trick phones with a jammer in a large area to make it look like all phones are in a specific point on Earth. Only with a jammer?
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.
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.
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.
Also see this one: https://www.lloydslist.com/LL1148748/War-zone-GPS-jamming-se...
I think it was due to Israel's some kind of defense measure against Iran.
There's a report on very similar jamming happening during the Syria conflict that will hopefully be enlightening as the methods and actors are presumably similar https://c4ads.org/wp-content/uploads/2022/05/AboveUsOnlyStar...
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.
Not necessarily jamming.