The Effects of GPS Carrier Phase Ambiguity Resolution on Jason-1

Abstract

We have used GPS carrier phase integer ambiguity resolution to investigate improvements in the orbit determination for the Jason-1 satellite altimeter mission. The technique has been implemented in the GIPSY orbit determination software developed by JPL. The radial accuracy of the Jason-1 orbits is already near 1 cm, and thus it is difficult to detect the improvements gained when the carrier phase ambiguities are resolved. Nevertheless, each of the metrics we use to evaluate the orbit accuracy (orbit overlaps, orbit comparisons, satellite laser ranging residuals, altimeter crossover residuals, orbit centering) show modest improvement when the ambiguities are resolved. We conservatively estimate the improvement in the radial orbit accuracy is at the 10–20% level.

Keywords:

• GPS
• ambiguity resolution
• orbit determination
• Jason-1

Acknowledgments

The author would like to thank the Orbiter and Radiometric Systems, and Satellite Geodesy and Geodynamics Systems groups at NASA Jet Propulsion Laboratory for their support and guidance in this study. Special thanks to Shailen Desai for providing JPL's reduced-dynamic orbit solutions, Da Kuang for assisting in the POD processing, and Yoaz Bar-Sever for providing the resources that make ambiguity resolution possible for Jason-1. The author is also grateful to John Ries at the University of Texas at Austin for providing the SLR/DORIS orbit solutions. A portion of this work was conducted at the Jet Propulsion Laboratory/California Institute of Technology in Pasadena, California. This work was supported by a NASA-funded Jason Science Investigation (PI: M. M. Watkins).