Skip to main content


Log in

Ambiguity resolution in precise point positioning with hourly data

  • Original Article
  • Published:
GPS Solutions Aims and scope Submit manuscript


Precise point positioning (PPP) has become a powerful tool for the scientific analysis of Global Positioning System (GPS) measurements. Until recently, ambiguity resolution at a single station in PPP has been considered difficult, due to the receiver- and satellite-dependent uncalibrated hardware delays (UHD). However, recent studies show that if these UHD can be determined accurately in advance within a network of stations, then ambiguity resolution at a single station becomes possible. In this study, the method proposed by Ge et al. J Geod 82(7):389–399, 2007 is adopted with a refinement in which only one single-difference narrow-lane UHD between a pair of satellites is determined within each full pass over a regional network. This study uses the EUREF (European Reference Frame) Permanent Network (EPN) to determine the UHD from Day 245 to 251 in 2007. Then 12 International GNSS Service stations inside the EPN and 15 outside the EPN are used to conduct ambiguity resolution in hourly PPP. It is found that the mean positioning accuracy in all hourly solutions for the stations inside the EPN is improved from (3.8, 1.5, 2.8) centimeters to (0.5, 0.5, 1.4) centimeters for the East, North and Up components, respectively. For the stations outside the EPN, some of which are over 2,000 km away from the nearest EPN stations, the mean positioning accuracy in the East, North and Up directions still achieves (0.6, 0.6, 2.0) centimeters, respectively, when the EPN-based UHD are applied to these stations. These results demonstrate that ambiguity resolution at a single station can significantly improve the positioning accuracy in hourly PPP. Particularly, UHD can be even applied to a station which is up to thousands of kilometers from the UHD-determination network, potentially showing a great advantage over current network-based GPS augmentation systems. Therefore, it is feasible and beneficial for the operators of GPS regional networks and providers of PPP-based online services to provide these UHD estimates as an additional product.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4

Similar content being viewed by others


  • Bar-Sever YE, Kroger PM, Borjesson JA (1998) Estimating horizontal gradients of tropospheric path delay with a single GPS receiver. J Geophys Res 103(B3):5019–5035. doi:10.1029/97JB03534

    Article  Google Scholar 

  • Blewitt G (1989) Carrier phase ambiguity resolution for the global positioning system applied to geodetic baselines up to 2,000 km. J Geophys Res 94(B8):10187–10203. doi:10.1029/JB094iB08p10187

    Article  Google Scholar 

  • Chen K (2004) Real-time precise point positioning and its potential applications. In: Proceedings of 17th Int Tech Meet Satellite Div Inst Navigation GNSS 2004 21-24 September, Long Beach, CA, USA

  • Collins P (2008) Isolating and estimating undifferenced GPS integer ambiguities. In: Proceedings of Inst Navigation National Tech Meet 28–30 January, San Diego, CA, USA

  • Dong D, Bock Y (1989) Global positioning system network analysis with phase ambiguity resolution applied to crustal deformation studies in California. J Geophys Res 94(B4):3949–3966. doi:10.1029/JB094iB04p03949

    Article  Google Scholar 

  • Euler HJ, Schaffrin B (1990) On a measure of the discernibility between different ambiguity solutions in the static-kinematic GPS mode. In: Proceedings of kinematic systems in geodesy, surveying and remote sensing, IAG Symposium 107, 10–13 September, Berlin, Heidelberg, New York

  • Gabor MJ, Nerem RS (1999) GPS carrier phase ambiguity resolution using satellite-satellite single difference. In: Proceedings of 12th Int Tech Meet Satellite Div Inst Navigation GPS 99, 14–17 September, Nashville, TN, USA

  • Ge M, Gendt G, Dick G, Zhang FP (2005) Improving carrier-phase ambiguity resolution in global GPS network solutions. J Geod 79(1–3):103–110. doi:10.1007/s00190-005-0447-0

    Article  Google Scholar 

  • Ge M, Gendt G, Rothacher M, Shi C, Liu J (2007) Resolution of GPS carrier-phase ambiguities in precise point positioning (PPP) with daily observations. J Geod 82(7):389–399. doi:10.1007/s00190-007-0187-4

    Article  Google Scholar 

  • Geng J, Shi C, Zhao Q, Liu J (2006) Integrated adjustment of LEO and GPS in precision orbit determination. In: VI Hotine-Marussi symposium on theoretical and computational geodesy, Springer, Berlin. doi:10.1007/978-3-540-74584-6_20

  • Ghoddousi-Fard R, Dare P (2006) Online GPS processing services: an initial study. GPS Solut 10(1):12–20. doi:10.1007/s10291-005-0147-5

    Article  Google Scholar 

  • Han S (1997) Quality-control issues relating to instantaneous ambiguity resolution for real-time GPS kinematic positioning. J Geod 71(6):351–361. doi:10.1007/s001900050103

    Article  Google Scholar 

  • Kouba J (2005) A possible detection of the 26 December 2004 great Sumatra-Andaman islands earthquake with solutions products of the international GNSS service. Stud Geophys Geod 49(4):463–483. doi:10.1007/s11200-005-0022-4

    Article  Google Scholar 

  • Kouba J, Héroux P (2001) Precise point positioning using IGS orbit and clock products. GPS Solut 5(2):12–28. doi:10.1007/PL00012883

    Article  Google Scholar 

  • Laurichesse D, Mercier F (2007) Integer ambiguity resolution on undifferenced GPS phase measurements and its application to PPP. In: Proceedings of 20th Int Tech Meet Satellite Div Inst Navigation GNSS 2007, 25–28 Semptember, Fort Worth, TX, USA

  • Liu J, Ge M (2003) PANDA software and its preliminary result of positioning and orbit determination. J Nat Sci Wuhan Univ 8(2B):603–609. doi:10.1007/BF02899825

    Google Scholar 

  • McCarthy DD, Petit G (2004) IERS Conventions (2003). IERS technical note No. 32. Verlag des Bundes für Kartographie und Geodäsie, Frankfurt am Main, 127 pp

  • Melbourne WG (1985) The case for ranging in GPS-based gedetic systems. In: Proceedings of first international symposium on precise positioning with the global positioning system, Rockville, 15–19 April, MD, USA, pp 373–386

  • Soler T, Michalak P, Weston ND, Snay RA, Foote RH (2006) Accuracy of OPUS solutions for 1- to 4-h observing sessions. GPS Solut 10(1):45–55. doi:10.1007/s10291-005-0007-3

    Article  Google Scholar 

  • Teferle FN, Orliac EJ, Bingley RM (2007) An assessment of Bernese GPS software precise point positioning using IGS final products for global site velocities. GPS Solut 11(3):205–213. doi:10.1007/s10291-006-0051-7

    Article  Google Scholar 

  • Tétreault P, Kouba J, Héroux P, Legree P (2005) CSRS-PPP: an internet service for GPS user access to the Canadian Spatial Reference Frame. Geomatica 59(1):17–28

    Google Scholar 

  • Teunissen PJG (1994) A new method for fast carrier phase ambiguity estimation. In: Proceedings of IEEE position, location and navigation symposium, Las Vegas, NV, April 11–15, pp 562–573

  • 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, MD, USA, pp 403–412

  • Zumberge JF, Heflin MB, Jefferson DC, Watkins MM, Webb FH (1997) Precise point positioning for the efficient and robust analysis of GPS data from large networks. J Geophys Res 102(B3):5005–5017. doi:10.1029/96JB03860

    Article  Google Scholar 

Download references


This research is supported by a scholarship provided to Mr. J. Geng by the University of Nottingham, the Chinese 973 project “Earth Observing Data Spatial Information-Transform Mechanism of Geodetic Knowledge” (No: 2006CB701301) and additional financial support from Prof. T. Marmont and Beacon Energy Ltd. The authors would like to thank Dr. Giorgi at the Technical University of Delft for the Fortran source code of LAMBDA, the developers of the Generic Mapping Tools, and Dr. Paul Collins and one anonymous reviewer for their critical and helpful suggestions, which greatly improved the manuscript. Thanks also go to the EUREF and IGS communities for the provision of GPS data and products.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Jianghui Geng.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Geng, J., Teferle, F.N., Shi, C. et al. Ambiguity resolution in precise point positioning with hourly data. GPS Solut 13, 263–270 (2009).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: