Resolution of GPS carrier-phase ambiguities in Precise Point Positioning (PPP) with daily observations
- 2.3k Downloads
Precise Point Positioning (PPP) has been demonstrated to be a powerful tool in geodetic and geodynamic applications. Although its accuracy is almost comparable with network solutions, the east component of the PPP results is still to be improved by integer ambiguity fixing, which is, up to now, prevented by the presence of the uncalibrated phase delays (UPD) originating in the receivers and satellites. In this paper, it is shown that UPDs are rather stable in time and space, and can be estimated with high accuracy and reliability through a statistical analysis of the ambiguities estimated from a reference network. An approach is implemented to estimate the fractional parts of the single-difference (SD) UPDs between satellites in wide- and narrow-lane from a global reference network. By applying the obtained SD-UPDs as corrections to the SD-ambiguities at a single station, the corrected SD-ambiguities have a naturally integer feature and can therefore be fixed to integer values as usually done for the double-difference ones in the network mode. With data collected at 450 stations of the International GNSS Service (IGS) through days 106 to 119 in 2006, the efficiency of the presented ambiguity-fixing strategy is validated using IGS Final products. On average, more than 80% of the independent ambiguities could be fixed reliably, which leads to an improvement of about 27% in the repeatability and 30% in the agreement with the IGS weekly solutions for the east component of station coordinates, compared with the real-valued solutions.
KeywordsGNSS Precise Point Positioning (PPP) Uncalibrated phase delay Integer ambiguity resolution Global network
Unable to display preview. Download preview PDF.
- Blewitt G, Hammond W, Kreemer C, Plag H-P (2005) From Yucca Mountain local stability to global quaking: GPS point positioning strategies spanning the spatio-temopral spectrum. Paper presented at advances in GPS data processing and modelling for geodynamics, University College London, 9–10 NovemberGoogle Scholar
- Bock H, Hugentobler U, Beutler G (2003) Kinematic and dynamic determination of trajectories for low Earth satellites using GPS. In: Reigber C, Lühr H, Schwintzer P (eds) First CHAMP mission results for gravity, magnetic and atmospheric studies, Springer, Heidelberg, pp 65–69Google Scholar
- Gao Y and Shen X (2002). A new method for carrier-phase-based precise point positioning. NAVIGATION J Inst Navig 49(2): 109–116 Google Scholar
- Ge M, Gendt G, Rothacher M (2006a) Integer ambiguity resolution for precise point positioning: applied to fast integrated estimation of very huge GNSS networks. Paper presented at VI Hotine-Marussi Symposium of theoretical and computational Geodesy, Wuhan 29 May–2 June 2006Google Scholar
- Gendt G, Dick G, Reigber CH, Tomassini M, Liu Y and Ramatschi M (2003). Demonstration of NRT GPS water vapor monitoring for numerical weather prediction in Germany. J Meteo Societ Jap 82(1B): 360–370 Google Scholar
- Liu J and Ge M (2003). PANDA Software and its preliminary result of positioning and orbit determination. Wuhan Univ J Nat Sci 8(2B): 603–609 Google Scholar
- Moulborne WG (1985) The case for ranging in GPS-based geodetic systems. In: Proceedings first international symposium on precise positioning with the global positioning system, Rockville, 15–19 April pp 373–386Google Scholar
- Rizos C (2006) The research challenges of IAG Commission 4 “Positioning & Applications”. Paper presented at VI Hotine-Marussi symposium of theoretical and computational geodesy, Wuhan 29 May–2 June, 2006Google Scholar
- Schaer S, Steigenberger P (2006) Determination and use of GPS differential code bias values. Paper presented at IGS Workshop, Darmstadt 8–11 May 2006Google Scholar
- Wu JT, Wu SC, Hajj GA, Bertiger WI and Lichten SM (1993). Effects of antenna orientation on GPS carrier phase. Manuscripta Geodaetica 18(2): 91–98 Google Scholar
- Wübbena G (1985) Software developments for geodetic positioning with GPS using TI-4100 code and carrier measurements. In: Proceedings of first international symposium on precise positioning with the global positioning system, Rockville, 15–19 April pp 403–412Google Scholar