How GPS & Satellite Trilateration Works
Pinpointing your exact position on Earth to within 1 meter using atomic clocks in orbit and Einstein's relativity.
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Step 11. Atomic Clock Timestamp Broadcast
Satellites broadcast orbital ephemeris and nanosecond timestamps.
Rubidium and Cesium atomic clocks on orbiting satellites emit synchronized CDMA radio signals at the speed of light.
Step 1 of 4How GPS & Satellite Trilateration Works
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GPS works like listening to multiple radio towers in space with super-accurate clocks to calculate your distance from each.
Key Takeaways
- ✓GPS uses a constellation of 31+ satellites orbiting 20,200 km above Earth.
- ✓Satellites broadcast the exact time and their orbital position continuously.
- ✓Your phone measures how long the radio signal took to travel at the speed of light.
Listening to Space Clocks
Whenever you open Google Maps or hail a ride, your phone does something extraordinary: it listens to faint radio whispers from satellites travelling at 14,000 km/h in space.Each GPS satellite contains an ultra-precise atomic clock that only loses one second every million years. By comparing the timestamp sent by the satellite with your phone's clock, your phone calculates the exact travel time of the radio wave ($t = d/c$) to determine distance.Interactive Challenge+25 XP