DGPS
From Wildsong
Defined in the WikiPedia entry http://en.wikipedia.org/wiki/Differential_GPS as follows:
"Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions."
NASA Global DGPS system http://www.gdgps.net/
For hams
DXing and decoding http://www.beaconworld.org.uk/dgps.htm
Homebrew DGPS http://web.abnormal.com/dgps/
