The advent of global navigation satellite systems, and especially GPS, signified a new era in navigation. Although GPS tends to be a panacea in terms of positioning and tracking, there are still cases whereby severe problems can render navigation virtually impossible. Difficult GNSS environments such as forests, heavy canopy covered areas, or urban canyons can have a negative impact on the propagation of satellite signal and introduce large errors in positioning due to signal attenuation. Several techniques have been developed to deal with this issue, e.g. integrated GNSS/INS navigation configurations. This thesis focuses on the application of terrain aiding and its impact on the availability, accuracy, and reliability of GNSS positioning. Furthermore, it examines the impact of using GNSS receivers of different grade and different chipset sensitivity in such operations. Two main experiments were carried out; the first was conducted in the mountains of Transylvania, in Romania. This project was sponsored by the European GNSS supervisory authority, and involved the tracking of animals (bears in this case). The second experiment was held in Greenwich Park, London, using an accurate terrain model, kindly provided by the Ordnance Survey of Great Britain. In both cases, new algorithms have been developed to combine satellite tracking with local terrain models to improve positioning performance. The results indicate that in the case of standard sensitivity receivers the use of an accurate digital terrain model can improve positioning availability by as much as 74%, and the accuracy of normal four-satellite positioning by a factor of up to five. Furthermore, it was found that, for both standard and high sensitivity receivers, the external reliability of position fixes can be improved by an average of 40%, and up to 90% in some cases.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:625654 |
| Date | January 2011 |
| Creators | Danezis, C. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1331877/ |
Page generated in 0.0014 seconds