[eltoozero]

US, Russia, and China all have intependant “Global Positioning” Systems, GPS, GLONASS and BDS.

All similar in function and implementation.

The coolest part about GPS is the fact that temporal relativity is employed to establish a 3D location from accurate flying clock radios, that’s rad.

[wyldfire]

There's a relativity correction step for communication between Iridium satellites and mobiles. I always thought that was really cool.

[azernik]

The EU also has one in deployment (Galileo).