Advertisement

Journal of Geodesy

, Volume 83, Issue 10, pp 953–966 | Cite as

Improving the GNSS positioning stochastic model in the presence of ionospheric scintillation

  • M. AquinoEmail author
  • J. F. G. Monico
  • A. H. Dodson
  • H. Marques
  • G. De Franceschi
  • L. Alfonsi
  • V. Romano
  • M. Andreotti
Original Article

Abstract

Ionospheric scintillations are caused by time- varying electron density irregularities in the ionosphere, occurring more often at equatorial and high latitudes. This paper focuses exclusively on experiments undertaken in Europe, at geographic latitudes between ~50°N and ~80°N, where a network of GPS receivers capable of monitoring Total Electron Content and ionospheric scintillation parameters was deployed. The widely used ionospheric scintillation indices S4 and \({\sigma_{\varphi}}\) represent a practical measure of the intensity of amplitude and phase scintillation affecting GNSS receivers. However, they do not provide sufficient information regarding the actual tracking errors that degrade GNSS receiver performance. Suitable receiver tracking models, sensitive to ionospheric scintillation, allow the computation of the variance of the output error of the receiver PLL (Phase Locked Loop) and DLL (Delay Locked Loop), which expresses the quality of the range measurements used by the receiver to calculate user position. The ability of such models of incorporating phase and amplitude scintillation effects into the variance of these tracking errors underpins our proposed method of applying relative weights to measurements from different satellites. That gives the least squares stochastic model used for position computation a more realistic representation, vis-a-vis the otherwise ‘equal weights’ model. For pseudorange processing, relative weights were com- puted, so that a ‘scintillation-mitigated’ solution could be performed and compared to the (non-mitigated) ‘equal weights’ solution. An improvement between 17 and 38% in height accuracy was achieved when an epoch by epoch differential solution was computed over baselines ranging from 1 to 750 km. The method was then compared with alternative approaches that can be used to improve the least squares stochastic model such as weighting according to satellite elevation angle and by the inverse of the square of the standard deviation of the code/carrier divergence (sigma CCDiv). The influence of multipath effects on the proposed mitigation approach is also discussed. With the use of high rate scintillation data in addition to the scintillation indices a carrier phase based mitigated solution was also implemented and compared with the conventional solution. During a period of occurrence of high phase scintillation it was observed that problems related to ambiguity resolution can be reduced by the use of the proposed mitigated solution.

Keywords

Global navigation satellites system Global positioning system Ionospheric scintillation Receiver tracking models Mitigation Stochastic model 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Aarons J (1997) Global positioning system phase fluctuations at auroral latitudes. J Geophys Res 102(A8): 17219–17232CrossRefGoogle Scholar
  2. Alves DBM, Monico JFG (2007) Modifying the stochastic model to mitigate GPS systematic errors in relative positioning. IAG Symposia (Springer), vol 130, Chapter 26, pp 166–171Google Scholar
  3. Alfonsi L, De Franceschi G, Romano V, Aquino M and Dodson A (2006) Positioning errors during the space weather event of October 2003. Location, ISSN 0973-4627, 1, issue 5Google Scholar
  4. Aquino M, Rodrigues FS, Souter J, Moore T, Dodson A, Waugh S (2005) Ionospheric scintillation and impact on GNSS users in Northern Europe: results of a 3 year study. Space Commun 20(1/2): 17–30Google Scholar
  5. Aquino M, Moore T, Dodson A, Waugh S, Souter J, Rodrigues FS (2005) Implications of ionospheric scintillation for GNSS users in Northern Europe. J Navig 58(2): 241–256CrossRefGoogle Scholar
  6. Aquino M, Monico JFG, Dodson A, Marques H (2006) Mitigating the effect of ionospheric scintillations on position estimates. In: online Proceedings of ESA 3rd European space weather week, Brussels, Belgium. http://sidc.oma.be/esww3
  7. Aquino M, Dodson A, Souter J, Moore T (2007a) Ionospheric scintillation effects on GPS carrier phase positioning accuracy: analysis at Auroral and Sub-Auroral latitudes. IAG Symposia (Springer), vol 130, chapter 121, pp 859–866Google Scholar
  8. Aquino M, Andreotti M, Dodson A, Strangeways H (2007) On the use of ionospheric scintillation indices as input to receiver tracking models. J Adv Space Res 40(3): 426–435CrossRefGoogle Scholar
  9. Béniguel Y (2002) GISM, A Global Ionospheric Propagation Model for scintillations of transmitted signals. Radio Sci 37(3). doi: 10.1029/2000RS002393
  10. Conker RS, El-Arini MB, Hegarty CJ, Hsiao T (2003) Modeling the effects of ionospheric scintillation on GPS/satellite-based augmentation system availability. Radio Sci 38(1):1001. doi: 10.1029/2000RS002604 Google Scholar
  11. De Franceschi G, Alfonsi L, Romano V (2006) ISACCO: an Italian project to monitor the high latitudes ionosphere by means of GPS receivers. GPS Solut 10(4): 263–267CrossRefGoogle Scholar
  12. De Franceschi G, Alfonsi L, Romano V, Aquino M, Dodson A, Mitchell C N, Wernik AW (2008) Dynamics of high latitude patches and associated small scale irregularities. J Atmos Solar-Terrestrial Phys 70: 879–888. doi:  10.1016/j.jastp.2007.05.018 CrossRefGoogle Scholar
  13. GPS Silicon Valley (2004) GSV4004/GSV4004A GPS Ionospheric Scintillation and TEC Monitor (GISTM) User’s ManualGoogle Scholar
  14. Grejner-Brzezinska D, Wielgosz P, Kashani I, Smith DA, Robertson DS, Mader GL, Komjathy A (2006) The impact of severe ionospheric conditions on the accuracy of kinematic position estimation: performance analysis of various ionospheric modeling techniques. Navigation 53(3): 203–217Google Scholar
  15. Kim BC, Tinin MV (2007) Contribution of ionospheric irregularities to the error of dual-frequency GNSS positioning. J Geod 81(3): 189–199CrossRefGoogle Scholar
  16. Moore T, Aquino M, Waugh S, Dodson A, Hill C (2002) Evaluation of the EGNOS ionospheric correction model under scintillation in Northern Europe. In: Proceedings of the 15th technical meeting of the satellite division of the Institute of Navigation: ION GPS 2002, Portland, Oregon, USA, pp 1297–1306Google Scholar
  17. Rodrigues FS, Aquino M, Dodson A, Moore T, Waugh S (2004) Statistical analysis of GPS ionospheric scintillation and short-time TEC variations over Northern Europe. J Inst Navig 51(1): 59–75Google Scholar
  18. Romano V, Pau S, Pezzopane M, Zuccheretti E, Zolesi B, De Franceschi G, Locatelli S (2007) The electronic space weather upper atmosphere (eSWua) project at INGV: advancements and state of the art. Ann Geophys 25:1–7 (in press)Google Scholar
  19. Skone S, Yousuf R, Coster A (2004) Performance evaluation of the Wide Area Augmentation System for ionospheric storm events. J Glob Position Syst 3(1–2): 251–258Google Scholar
  20. Souza EM, Monico JFG (2007) The wavelet method as an alternative for reducing ionospheric effects from L1 GPS receivers. J Geod 81(12): 799–804CrossRefGoogle Scholar
  21. Strangeways HJ (2008) Determining scintillation effects on GPS receivers. In: Proceedings of the 12th international ionospheric effects symposium IES2008, Alexandria, Washington DC, USA, 13–15 May 2008, pp 550–557Google Scholar
  22. Teunissen PJG (1996) GPS carrier phase ambiguity fixing concepts. In: Kleusberg A and Teunissen P (eds) GPS for Geodesy. Verlag, Berlin, pp 263–336Google Scholar
  23. Van Dierendonck AJ, Klobuchar J, Hua Q (1993) Ionospheric scintillation monitoring using commercial single frequency C/A code receivers. In: Proceedings ION GPS-93: sixth international technical meeting of the satellite division of the Institute of Navigation, Salt Lake City, Utah, pp 1333–1342Google Scholar
  24. Van Dierendonck AJ (2001) Measuring ionospheric scintillation effects from GPS signals. In: Proceedings of 57th annual meeting of the Institute of Navigation, Albuquerque, New Mexico, USA, pp 391–396Google Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • M. Aquino
    • 1
    Email author
  • J. F. G. Monico
    • 2
  • A. H. Dodson
    • 1
  • H. Marques
    • 2
  • G. De Franceschi
    • 3
  • L. Alfonsi
    • 3
  • V. Romano
    • 3
  • M. Andreotti
    • 4
  1. 1.Institute of Engineering Surveying and Space Geodesy (IESSG)University of NottinghamNottinghamUK
  2. 2.Department of CartographySao Paulo State UniversitySão PauloBrazil
  3. 3.Instituto Nazionale di Geofisica e Vulcanologia (INGV)RomeItaly
  4. 4.Geospatial Research Center Ltd.ChristchurchNew Zealand

Personalised recommendations