They can use an IMU and computers to get pretty darn close even without GPS or the Russian system Glonass.
https://www.quora.com/How-many-countries-have-their-own-GPS-system
There are other regional GPS like systems.
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Glen
49 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
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