Originally Posted by
Dee Vee
I have no idea how they did it, some said China somehow manipulated the map data companies like google had, but when I was in China a few years ago, using on your phone or imported GPS, google maps would always show your actual location (on a map) hundreds of metres away from where you actually were.
The Chinese GPS's worked perfectly (if you could read them
)
Locally jamming GPS is very easy, as is position spoofing over a limited area. A few years ago we had regular warnings of GPS outages around the Salisbury Plain area, which I am pretty sure was due to the testing of GPS jamming. Spoofing position is harder, but I remember seeing a demo of this at Farnborough about 20 years ago, so it's certainly possible to do it. IIRC, the spoofing worked by setting up fixed transmitters that faked the SV C/A code, complete with realistic velocity changes, that were more powerful in the local area than the GPS signal. The demo I saw was small scale, inside a hangar, but was just a proof-of-principle test.
Also, someone mentioned a while ago that you could buy cheap, portable, GPS jammers pretty easily, and these were used by car thieves to disable the GPS in any car on-board tracker.