Satellites Time the Phone

In the picture

1. 1Satellite: sends a radio signal with its time
2. 2Phone: records when each signal arrives
3. 3Signal path: travel time from satellite to phone gives a distance
4. 4Map pin: the computed position on the map

Examples

• A maps app showing a blue dot on a city street
• A fitness watch tracing the route of a run

Quiz: Satellites Time the Phone (Age 15)

1. 1

   What does comparing signal travel time from a satellite give the phone?

   • The phone owner’s name
   • The distance from that satellite
   • The satellite’s exact battery level
2. 2

   Why does the phone need signals from several satellites?

   • Several signals make the map pin larger
   • Together they narrow the position to one point
   • One signal is enough for every location
3. 3

   What does the phone record to use each satellite’s signal?

   • The colour of each satellite
   • When each signal arrives
   • The number of apps open

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.