Transforming the way the world works

How GPS works?

In five logical steps

Here's how GPS works in five logical steps:

  • The basis of GPS is "triangulation" from satellites.
    We're using the word "triangulation" very loosely here because it's a word most people can understand, but purists would not call what GPS does "triangulation" because no angles are involved. It's really "trilateration."
    Trilateration is a method of determining the relative positions of objects using the geometry of triangles.
  • To "triangulate," a GPS receiver measures distance using the travel time of radio signals.
  • To measure travel time, GPS needs very accurate timing which it achieves with some tricks.
  • Along with distance, you need to know exactly where the satellites are in space. High orbits and careful monitoring are the secret.
  • Finally you must correct for any delays the signal experiences as it travels through the atmosphere.

We'll explain each of these points in the next five sections of the tutorial. We recommend you follow the tutorial in order. Remember, science is a step-by-step discipline!