Abstract for presentation at Spatial Sciences Institute International Biennial Conference

Satellite orbit, clock and atmosphere are the main sources of error for standalone GPS positioning since the removal of Selective Availability (SA) in May 2000. But with the timely availability of precise ephemeris and clock correction products by the International GNSS Service (IGS), standalone positioning accuracy can now be improved to centimetre or decimetre level. Obtaining high accuracy positions from a single GPS receiver using precise ephemeris and clock correction products is known as Precise Point Positioning (PPP).
This paper investigates the fundamental components of PPP and makes comparison with differential techniques. To date, the investigation on PPP has been primarily focussed on the use of precise IGS products for accurate point positioning in post-mission applications. Various data sets were post-processed for location using both the contemporary PPP and traditional differential techniques (including online services and commercial software). The results from PPP were then compared with those from the differential techniques. Numerical comparison clearly demonstrated that centimetre level (< 0.01m to 0.09m) point positioning accuracy is achievable in PPP by using dual frequency GPS observations. As for single frequency GPS receiver users, decimetre level (< 0.1m to 0.9m) point positioning accuracy can be expected.