What is DGPS?
Differential GPS (DGPS) or indeed any Differential Global Navigation Satellite System (DGNSS) in general, greatly increases the potential accuracy of either GPS or GLONASS. By determining the major error sources at a base station and applying the corrections thus derived to any other station (which may be mobile), these errors can be largely eliminated. If the correction values are supplied to the mobile station in real time, its position can also be determined in real time to the required accuracy. With code-only observations one metre accuracy can be achieved. With carrier phase observations the accuracy can be increased to better than one centimetre, so this carrier phase differential (CPD) GPS has sometimes been described as precise DGPS (PDGPS).