wrote:

https://rntfnd.org/2020/04/27/norway-powerless-against-gps-interference-nrk/

This issue is not confined to northern Norway. There is a stretch of
the East River in New York Harbor near UN Headquarters where there
have been many well documented instances of GPS jamming. We've
experienced it ourselves.

Apparently jammers are easy to buy:

https://gizmodo.com/jamming-gps-signals-is-illegal-dangerous-cheap-and-e-1796778955

It looks like we're going to need some new form of electronic
navigation some time in the future, something more difficult to jam.


The power output of GPS stats is very low. So easy to jam, spoof is
harder, but easy to override a very low power signal. Sats transmit at
less than 50 watts. Even with a decent gain antenna, the receivers get a
very low power signal. How many square miles does that 50 watts cover?