Differential operation of the Global Positioning System

Abstract

The principles of differential operation of the Global Positioning System (DGPS) are discussed. DGPS error sources and their influence on spatial and temporal correlation are analyzed. The standards for the differential corrections and the auxiliary messages which have been developed by the Radio Technical Commission for Maritime Services are then described. The dependence of DGPS accuracy on satellite geometry is examined. Two possible DGPS data links are described, and the applications, advantages, and limitations of each are discussed. The first data link would use the extant marine radiobeacon network (a medium-frequency system) and provide coastal coverage. The second data link would use pseudosatellites and provide additional lines of position as well as carry the differential correction.