Precise Positioning with Low-Cost GPS

Aim:

The research is focussed on the use of phase information of GNSS low-cost receivers for cm-level accuracy.

Procedure:

Low-Cost GNSS receivers are characterised by cost clearly below 100 €. Additionally a sensitivity better -150 dBm with respect to attenuated and reflected signals is given. The second characteristic predispose these receiver type for navigational use in shadowed areas like urban canyons. The instruments use phase-smoothed code measurements for positioning.

For recent investigations at IIGS the u-blox AEK-4T Evaluation Kit was used, since this receiver shows the possibility to readout phase data. The figure shows the u-blox AEK-4T receiver and the respective ANN-MS-antenna The processing is realised in post-processing. For this task the software TEQC is used for decoding of the raw data. The software Wa1 is utilised for processing the decoded data and position determination. For a user-friendly program control, the new software “GPS tools” was developed at IIGS.

 

 Fig. 1: u-blox AEK-4T (© iigs)

 

 gnss_leica

 

 

 

 

 

 

 

Fig. 2: Typiscal measurement arrangement (left: Low-Cost; right Leica receiver) (© iigs)

 

Results:

The usage of default processing parameters leads to an average 3D-RMS of 2.4 cm for 30 minutes observation period. If environments as far as possible without shadowing and multipath effects are chosen, the average 3D-RMS is 2.0 cm for 20 minutes observation period. In this case the solutions are 100 % reliable and correct. These results are valid for baselines up to 7.7 km length.

References:

  • Weston, N.D., Schwieger, V.: Cost Effective GNSS Positioning Techniques. FIG Publication No 49, FIG Commission 5 Publication. The International Federation of Surveyors, Copenhagen, Denmark, 2010.
  • Schwieger, V.: High-Sensitivity GPS - an Availability, Reliability and Accuracy Test. INCT Bulletin des Sciences Geographiques, Institut National de Cartographie e de Teledetection (INCT), Algier, Algerien, No 23, September 2009.
  • Schwieger, V.: Accurate High-Sensitivity GPS for Short Baselines. FIG Working Week, Eilat, Israel, 03.-08.05.2009.
  • Schwieger, V.: High-Sensitivity GPS für geodätische Anwendungen. 83.DVW-Seminar, GNSS 2009: Systeme, Dienste, Anwendungen. Dresden, 18.-19.03.2009.
  • Schwieger, V.: High-Sensitivity GPS - an availability, reliability and accuracy test. Proceedings on FIG Working Week, Stockholm, Schweden, 14.-19.06.2008.
  • Schwieger, V.: High-Sensitivity GNSS – the Low-Cost Future of GPS ?. Proceedings on FIG Working Week 2007, Hongkong SAR, 13.-17.05. 2007.
  • Schwieger, V., Wanninger, L.: Potential von GPS Navigationsempfängern. In: GPS und Galileo. Beiträge zum 66. DVW-Seminar am 21. und 22. Februar 2006 in Darmstadt, Wißner Verlag, Augsburg, 2006.
  • Schwieger, V.: Quality of Low-Cost GPS for Geodetic and Navigation Applications. GIS@development Middle East, Heft Nr. 5, September - Oktober, 2005.
  • Schwieger, V, Gläser, A.: Possibilities of Low Cost GPS Technology for Precise Geodetic Applications. Proceedings on FIG Working Week 2005, Kairo, Ägypten, 16.-21.04. 2005.
  • Schwieger, V.: Zum ingenieurgeodätischen Einsatz von Low-Cost GPS-Empfängern. In: Festschrift zur Emeritierung von Prof. Hans Pelzer, Wissenschaftliche Arbeiten der Fachrichtung Vermessungswesen der Universität Hannover, Heft Nr. 250, Universität Hannover, 2004.
  • Schwieger, V.: Using Handheld GPS receivers for precise positioning. Proceedings on 2nd FIG regional conference, Marrakesh, Marocco, 2.-5.12. 2003.

Contact:

Prof. Dr.-Ing. habil. Volker Schwieger
Dipl.-Ing. Li Zhang