The Space Segment
This segment consists of the satellites that orbit the earth. These satellites send out time-marked microwaves towards the Earth.
The Control Segment
These are stations on the Earth that send and receive data by way of the satellites.
The User Segment
This segment consists of the individual users and their GPS units.
How the System Works
You turn on your GPS unit. The GPS unit searches for satellites and the closest control station. The more satellites your GPS can find, the more accurate your location will be; most units will go for four satellites. Using the microwaves emitted, the GPS unit will be able to be pinpointed anywhere the satellites reach.
The accuracy of the GPS unit is determined by how many satellites are in contact with it. Other determining factors are sunspots, stormy weather patterns and the location of tall buildings around your position. Some of the most powerful GPS units can be accurate up to three feet, while most are accurate to about 48 feet.
Article Written By Heather Broeker
Originally from North Carolina, Heather Broeker studied journalism and advertising at the University of North Carolina. After graduation she moved to Los Angeles, where she worked for Fox Searchlight, Fox Reality and later as a writer and marketing director. Broeker now lives in Los Angeles and runs Head Over Heels, a writing and public relations company.