Uncorrected GPS data can be off by as much as 15 meters due to uncertainty of GPS satellites’ positions, drift in satellite clocks and interference from Earth’s atmosphere. Beginning in the 1990s, researchers at NASA’s Jet Propulsion Laboratory (JPL) developed software capable of correcting for those errors in the data streamed from JPL’s global network of GPS receivers. NASA monitors the integrity of global GPS data in real time for the U.S. Air Force, which administers the positioning service worldwide. JPL also delivered the software to enable the system that commercial and private pilots now use to navigate and land in U.S. air space, and it supports all the world’s major precision-GPS providers with corrective data, enabling accuracy up to within five centimeters. Such accurate GPS is used by, among others, the military, offshore drilling operations and self-driving tractors, which today work the majority of North American farmland. Many cell phones also use data from JPL not for positioning but to get a quick GPS signal and navigate without using a wireless connection.
Read more: http://spinoff.nasa.gov/Spinoff2010/ct_7.html
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