How does GPS work?
A person (or receiver) is located some distance from a satellite. This means that their position could be anywhere on a hollow imaginary sphere centered on the satellite whose radius is the distance between the person and the satellite.
The person is located a different distance from a second satellite. A sphere can be drawn from this location as well. The person's position lies someplace where the two spheres intersect.
The person is located a distance from a third satellite and the process is repeated. The person's location is where all three spheres intersect. The red dots show that the sphere's intersect at two points. One of the two points can be ignored because it does not lie on Earth's surface. The other point is the person's location.
The person is located a different distance from a second satellite. A sphere can be drawn from this location as well. The person's position lies someplace where the two spheres intersect.
The person is located a distance from a third satellite and the process is repeated. The person's location is where all three spheres intersect. The red dots show that the sphere's intersect at two points. One of the two points can be ignored because it does not lie on Earth's surface. The other point is the person's location.
