Absolute kinematic GPS positioning using satellite clock estimation every 1 second

Abstract

An algorithm for absolute positioning through satellite clock estimation has been developed. Using IGS precise orbits and measurements, the GPS clock errors were estimated at 30-second intervals and these estimates were compared to values determined by JPL. The agreement was at the level of about 0.1 nsec (3 cm). The clock error estimates were then used in an application of a single-differenced (between satellite) positioning algorithm in static and kinematic mode. For the static case, an IGS station was selected and the coordinates were estimated. The estimated absolute position coordinates and the known values had a mean difference of up to 18 cm with standard deviation less than 2 cm. For the kinematic case, data (every second) obtained from a GPS buoy were tested and the result from the absolute positioning was compared to a DGPS solution. The mean difference between two algorithms is less than 45 cm and the standard deviation is less than 30 cm. It was proved that a higher rate of satellite clock determination is necessary to do absolute kinematic positioning at better than 10 cm precision.