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📘 How GPS Finds Your Location

GPS does not ask a satellite to point down at your phone. Each satellite broadcasts a radio signal carrying a precise timestamp and information about its own position. Your receiver listens for several signals, records when they arrive, and

3
lessons
~15 min
to learn
Adults
level
Start the course →

What you’ll learn

  1. A Clock in the SkyExplain how signal travel time becomes distance and why four satellites are useful.GPS receivers compare satellite timestamps, turn travel times into ranges, and solve for position plus local clock error.
  2. Keeping the System HonestDescribe the satellite, ground, and timing infrastructure behind GPS accuracy.Atomic clocks, ground monitoring, orbit corrections, and relativity corrections keep the broadcast model aligned with reality.
  3. Why the Blue Dot WobblesIdentify multipath and satellite geometry as sources of position uncertainty.Reflections and poorly spread satellite lines of sight can make an otherwise working receiver less accurate.

Questions this course answers

Why does a practical GPS fix use at least four satellites?

The receiver must solve for latitude, longitude, altitude, and the error in its local clock.

Match each system part to its job.

The space, ground, and user segments divide the timing and positioning work.

Why can a receiver near tall buildings show a less stable position?

Reflections create multipath, which can distort the measured signal travel time.

Grounded in trusted sources

  • GPS.gov, Trilateration: https://www.gps.gov/trilateration
  • GPS.gov, GPS and Telling Time: https://www.gps.gov/gps-and-telling-time
  • ESA, How satellite navigation works: https://www.esa.int/Applications/Satellite_navigation/Galileo/First_Galileo_Launch/How_satellite_navigation_works
  • ESA, Galileo on the ground: https://www.esa.int/Applications/Satellite_navigation/Galileo/Galileo_on_the_ground
  • NIST, Putting Einstein to the Test: https://www.nist.gov/atomic-clocks/a-powerful-tool-for-science/putting-einstein-test
  • NOAA National Geodetic Survey, What is geodesy?: https://www.ngs.noaa.gov/INFO/facts/geodesy.shtml

Every Wunder lesson is built from real, reputable sources — never invented.

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