Time to Find Your Way
All scenes › Chapter 1 How Does Your Phone Know?
How does your phone know where you are?
Even in a field with no signs, the dot on your map lands right on you
View in 3DHow does your phone know where you are?
A car is driving across a wide, open field. There are no road signs and no buildings around. Yet the dot on the phone’s map sits exactly where the car is. How does the phone know? The answer is high in the sky, in the satellites circling Earth.
Why?Your phone has no built-in ruler for measuring where it is. Cell towers and Wi-Fi can give a rough idea, but getting within a few meters in the middle of the sea or the mountains is thanks to satellites.
Learn moreThis system is called GPS, short for Global Positioning System, built by the United States. Europe, Russia and China have launched satellites that work the same way, and today’s phones listen to several of them at once. The car’s spot here is just an example, and the car marker is drawn big so you can see it.
- A car in the middle of a field
- You are here = ?
textbook formulas
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Wikipedia: Global Positioning System
More in the series
Orbits, distances and clock differences are calculated with textbook formulas (Kepler’s laws and simple forms of special and general relativity). The 30 satellites follow the real GPS layout but are not the real satellites or positions. In the 3D view, the satellite models are drawn huge and radio waves move far slower than in real life.