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this post was submitted on 23 Nov 2023
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This sounds rather dangerous. GPS was originally opened up to civilian use for the purpose of keeping flights on course, after the disaster of Korean Air Flight 007 straying into Soviet airspace and being shot down back in the 1980s.
I can't understand what is to be gained by deliberately trying to knock civilian airliners off course.
GPS guided drone attacks. Civilian GPS top out at 300 m a second. Anything beyond that is a missile and GPS refuses to work unless you have one of the special government GPS chips without the limiter.
Would that be relevant for a drone attack? I wouldn't think a drone that isn't operated by a state actor is likely to be moving that fast, and presumably a state actor could build their own chips without a limiter?
Thus the point of the spoofing. A drone will be moving much slower than 300 m/s, so spoofing GPS would be an attempt to force it off-course.
Ah, I see, I misunderstood what you meant
Are you meaning 300 measurements per second? Because civilian gps has an accuracy of ~3 meters. I may be misunderstanding though
The GPS chips have internal limits on how fast they think they can move. If they determine that they are moving faster than 300m/s they will stop outputting any results for a period of time. This limit is, IIRC, put in at the silicon level, so only military chips can bypass it.
If you try to use mapping apps on a plane you sometimes run into this issue.
It is trivial to make your GPS receiver firmware ignore these limits. There are even open-source receivers (SwiftNav piksi, for example). Modifying a binary is much harder, but not impossible for a motivated state like Iran or Russia. It's best to think of the COCOM limits as suggestions.
But even the fastest airliners at the moment (A330 neo) moves slower than 300m/s. Wikipedia claims that COCOM limits are even higher so I don't think that they are the reason for the inaccurate tracking on planes.
There's also a height limit
Turns out it's 1000 knots (~600m/s), or 18,000 feet. So it's the altitude in this case. But a slow-moving drone at <18,000ft is fine.
Maybe a misapplication then. I've run into it with model rocketry before (for good reason)
Oh, neat. I was not aware of that. I have seen that before but thought it was due to the phone not being able to lock on to the signal from inside a big metal tube.
Holy shit, that really happened? Just finished watching "For All Mankind" and recognized some events, but had no idea this one was real.
You don't deal with terrorists, do you?