How it works
GPS satellites circle the earth twice a day in a very precise orbit
and transmit signal information to earth. GPS receivers take this
information and use triangulation to calculate the user's exact
location. Essentially, the GPS receiver compares the time a signal was
transmitted by a satellite with the time it was received. The time
difference tells the GPS receiver how far away the satellite is. Now,
with distance measurements from a few more satellites, the receiver
can determine the user's position and display it on the unit's
electronic map.
A GPS receiver must be locked on to the signal of at least three
satellites to calculate a 2D position (latitude and longitude) and
track movement. With four or more satellites in view, the receiver can
determine the user's 3D position (latitude, longitude and altitude).
Once the user's position has been determined, the GPS unit can
calculate other information, such as speed, bearing, track, trip
distance, distance to destination, sunrise and sunset time and more.
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