@AC Re: AFAIK
Most interference systems overwhelm the signal, so the original is not detected. So harder to protect against.
Uhm not really.
The spoof requires that you feed in fake data. If the signal is encrypted and you don't know the key, you can't really spoof the signal, only jam it.
And jamming the signal isn't enough.
There are other ways to ascertain your position in the event of a loss of GPS.