Your Phone Listens for Timing Signals from Space
GPS satellites continuously broadcast radio signals that include the time each signal was sent and the satellite’s orbital information. Your phone’s GPS receiver picks up those signals and compares their arrival times with the broadcast times. Because radio waves travel at a known speed, even a tiny delay reveals how far away each satellite is.
With distance estimates from several satellites, the phone calculates where those distances intersect. This is called trilateration: locating a point from its distances to known points. The receiver also accounts for the slight mismatch between its own clock and the satellites’ clocks, which is why it typically needs signals from at least four satellites to find a reliable position in three dimensions.
What the Network Connection Actually Adds
GPS signals travel one way—from satellites to your phone. The satellites do not need to know where you are, and your phone does not have to send them anything. Cell service and Wi-Fi therefore are not required for the basic position calculation.
A network connection can still make finding a position faster. Assisted GPS can provide the phone with current satellite information and a rough idea of where to look, rather than making it search from scratch. Wi-Fi networks and cell towers can also help estimate location, especially indoors or among tall buildings, where satellite signals are weak or blocked.
Position Is Not the Same as Navigation
A location dot can be calculated offline, but a navigation app may still need downloaded map data to show roads, search for places, or build a route. If the map is stored on the phone, GPS can keep updating your position without a connection; if it is not, the phone may know where you are while having little useful map detail to display.
