Mechanics of GPS

Shri Khalpada of PerThirtySix explains how GPS works using a set of small interactive globes.

The answer is in some ways simpler than you’d expect, and in other ways more complex. GPS is fundamentally a translation tool: it converts time into distance. A satellite sends a signal, your phone catches it, and the delay between those two events tells the phone exactly how far away the satellite is. Everything else is about making that measurement precise enough to be useful: accounting for bad clocks, satellite geometry, and eventually, Einstein’s theories.

So geometry is useful. Imagine that.