Global Positioning System (GPS)

The Global Positioning System (GPS) was established in 1993, when the last of 24 satellites was launched into orbit. A GPS receiver uses information from at least three of these satellites to triangulate its latitude, longitude and often elevation to identify the receiver's location anywhere in the world.



Latitude and longitude measures are accurate within several meters. Elevation measured by GPS mathematics is not as accurate and can fluctuate as much as 150 meters. GPS tracking devices that are made with barometric altimeters are much more accurate for measuring elevation.

Uses of GPS

• GPS is used in conjunction with atomic clocks to keep timing on wireless data systems synchronized. The timing allows business transaction times to be noted and supports digital radio systems for transmitting data. Power companies synchronize the power grids based on time information from GPS signals.
• GPS mapping is used for roads as well as in agriculture for mapping farmland. Farmland boundaries, soil sample locations, pest and weed locations and other information can be noted and tracked. This can assist crop dusting and in managing irrigation.
• Marine and railroad transportation systems also use GPS information to track ship travel and assist in managing ports. For railroad or commuter train travel, GPS information improves rail traffic flow and keeps scheduling information available.
• Military GPS usage includes all of the above systems and more. The U.S. Department of Defense does active tracking of events all over the world.