Solution of regional GPS network using Precise Point Positioning with undifferenced data

Precise Point Positioning (PPP) is the precise point positioning of a single station by carrier phase and pseudo-range data, while both the precise ephemeris and clock parameters are fixed. Because no parameters common to different stations are estimated here, there is no correlation among the stations, and so the computation is greatly reduced. We use the GPS analysis software GIPSY of Jet Propulsion Laboratory (JPL), USA, for an analysis of the APSG (Asian-Pacific Space Geodynamics Program) GPS campaigns. The results show that the PPP is comparable in repeatability to the double-difference (DD) algorithm, widely used in China. The non-fiducial algorithm is used for maintaining better the station configuration. The results after a Helmert transformation show that the PPP and the DD are comparable as regards external consistency, while the computation time for a same amount of data is 3.5 hours for the PPP and 18 ∼ 20 hours for the DD. Therefore, the PPP can be expected to contribute usefully to the data reduction of the forthcoming Chinese giant science-engineering project—earthquake monitoring GPS network with up to 2000 receivers, by reducing the computer time while maintaining the same precision.