Point real-time kinematic positioning

Abstract

Autonomous point positioning was the original aim of GPS. However, due to errors caused by satellite ephemerides, satellite clock corrections, ionosphere, troposphere, multipath and noise, the accuracy of autonomous point positioning cannot be better than a couple of meters, even after Selective Availability (SA) was turned off. Nowadays, with the emergence of Point Real-Time Kinematic (P-RTK) positioning, a lot of attention is again focused on standalone positioning. This method arose from the availability of precise ephemeris and satellite clock corrections. The concept behind this method is to make use of un-differenced code and carrier phase observations along with precise corrections to get the best accuracy out of GPS. The concepts, challenges, processing steps and results of the P-RTK system are presented in this paper. Currently at the University of Calgary, a software system has been developed that achieves centimeter to decimeter level accuracy with a single GPS receiver. All components of P-RTK have been incorporated in this software, which is portable and user-friendly, containing many graphical interface tools for analyzing data.