An analysis of single point positioning with real-time internet-based precise GPS data

  • Chen Kong-zhe
  • Gao Yang
  • Shen Xiao-bing


Single Point Positioning (SPP) is currently capable of providing position accuracy of several meters. To obtain a better accuracy, the Differential GPS (DGPS) method must be applied. For large-scale applications such as aerial survey and mapping, however, the requirement of a base station(s) in conventional DGPS often become problematic in practice due to the increased operational cost and complexity. Recently a concept of Global Differential GPS (GDGPS) has attracted increasing interests among the GPS communities. GDGPS has the same user’s implementation as SPP, but its accuracy is augmented by the globally or regionally distributed precise GPS data currently including precise satellite orbit and clock corrections. The major advantage of GDGPS lies in two aspects: system simplicity at the user’s end, and globally consistent positioning accuracy. This paper presents GDGPS positioning results using the precise GPS data generated by the Natural Resources Canada (NRCan). NRCan’s precise data can be retrieved real-time from Internet base on Virtual Private Network (VPN) and Multicast technology. The packet delay and Packet Loss Rate (PLR) of multicasting over Internet will first be investigated. The total latency of precise GPS data as well as the position accuracy of GDGPS will then be analyzed. The numerical results have shown that a meter to half-meter level accuracy is obtainable based on epoch-by-epoch data processing. With phase-smoothed code observations, the positioning accuracy can be further improved.

Key words

single point positioning DGPS GDGPS VPN multicast multipath 

CLC number

P 228.4 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Gao Y, Shen X, Abdel-Salem M. Global Differnetial GPS wihtout a Base Station.Journal of Geographic Information Sceinces, 2002,8(1):9–15.Google Scholar
  2. [2]
    Muellerschoen R J, Bertiger W I, Lough M,et al. An Internet-Based Global Differential GPS System, Initial Results.Proceedings of ION GPS 2000. Salt Lake City: UT, September, 2000.Google Scholar
  3. [3]
    Witchayangkoon B, Segantine P C L. Testing JPL’s PPP Service.GPS Solutions, 1999,3(1):73–76.CrossRefGoogle Scholar
  4. [4]
    Hada H, Sunahara H, Uehara H, et al. New Differential and RTK Corrections Service for Mobile Users Based on the Internet.Proceedings of ION GPS 1999, September 1999, Nashville, TN 14–17.Google Scholar
  5. [5]
    Hada H, Yamaguchi S, Kawakita Y,et al. Design of Internet Based Reference Station Network for New Augmentation System.Proceedings of ION GPS 2001. 11–14 September, Salt Lake City: UT, 2001.Google Scholar
  6. [6]
    Petrovski I, Hada H, Sasano K,et al. New Flexible Network-based RTK Service in Japan.Proceedings of ION GPS 2000, 19–22 September, Salt Lake City: UT, 2000.Google Scholar
  7. [7]
    Lahaye F, Caissy F, Héroux M,et al. Canadian Active Control System Real-Time GPS Correction Service Performance Review.Proceedings of the National Technical Meeting of the Institute of Navigation, Santa-Monica, USA, January 14–16, 1997. 695–698.Google Scholar
  8. [8]
    GSD, NRCan. GPS-C Interface Control Document. 2002.Google Scholar
  9. [9]
    Caissy M, Héroux P, Lahaye F,et al. Real-Time GPS Correction Service of the Canadian Active Control System.Proceedings of ION GPS 1996, September 17–20, 1996. 1787–1791.Google Scholar
  10. [10]
    Parkinson B W, Kee C. Wide Area Differential GPS.Global Positioning System: Theory and Applications Volume II, Volume 163, Progress in Astronautics and Aeronautics, The American Institute of Aeronautics and Astronautics, Washington, 1996. 81–114.Google Scholar

Copyright information

© Springer 2003

Authors and Affiliations

  1. 1.Department of Geomatics EngineeringThe University of CalgaryCalgaryCanada

Personalised recommendations