How GPS knows where you are
Process map by Brian. 18 steps, 2 layers. Tags: tech, science.
- GPS satellites: Each satellite broadcasts its position and the exact time
- Your phone: Pick up the signals
- Your phone: Can it hear at least four satellites?
- Your phone: Measure how long each signal took to arrive
- Your phone: Turn the delays into distances
- Your phone: Find the one point that fits all of them (trilateration)
- GPS satellites: Correct for Einstein's relativity, or errors build up fast
- The map app: Snap the point to the nearest road
- You: The blue dot appears
- You: Move outdoors or wait for a clear sky