What does D-GPS stand for?

Differential Global Positioning System

An advanced form of GPS navigation which provides greater positioning accuracy than the standard GPS. DGPS relies on error correction transmitted from a GPS receiver placed at a known location. This receiver, called a reference station, calculates the error in the satellite range data and outputs correction for use by mobile GPS receivers in the same locale. DGPS eliminates all the measurement errors in the satellite ranges, enabling a highly precise position calculation. Diffuser