Video narration
How does the blue dot on your map know where you are? GPS satellites don't send your phone its location. They broadcast timed signals. Your phone measures how long each signal takes to arrive. Since they travel at a known speed, that time tells it how far away each satellite is. Now the phone compares distances from several satellites, finding the spot that fits them all. That's where the blue dot goes. But the satellites don't know where your phone is. Your phone does the calculating. Four or more satellite signals help it solve for both its position and its own clock's timing error. Signals can be delayed or blocked, making the dot less accurate. So how does your map place its blue dot? It times satellite signals, turns travel time into distance, and finds the one spot that fits.