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1 Technical Sciences / University of Warmia and Mazury in Olsztyn

1 2024

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Advanced, on-line gnss multi-constellation mission planning and multipath mitigation tool

Tomaszewski Dariusz, Rapiński Jacek, Janowski Artur

Technical Sciences / University of Warmia and Mazury in Olsztyn

2024

Vol. 27

409--428

Despite the growing number of satellites in multi-constellation GNSS positioning systems, the issue of signal availability and quality persists in urban and forest areas. Additionally, obstacles such as high buildings or dense vegetation can lead to severe multipath problems. Various methods have been developed to mitigate the impact of multipath on measurement results, including optimizing antenna placement, antenna type, receiver type, and employing measurement post processing techniques. However, despite these efforts, multipath interference cannot be completely eliminated and can significantly impact positioning accuracy. To tackle this challenge, a tool GNSS MPD for predicting satellite signal obstruction was developed. This tool considers Line of Sight (LOS) vectors between specific locations and satellite positions, as well as obstacle models derived from airborne LiDAR data. The LiDAR data is automatically acquired from geoportal.gov.pl, and an approximate terrain cover model is generated. Satellite obstructions are then validated using a ray casting method. The authors of the study outlined the platform’s design and implementation. Subsequently, two experiments were conducted. The first experiment consisted in comparing the obtained satellite visibility scenarios with the results obtained from hemispherical photography. The second study involved performing five daily satellite observations in an area characterized by severe terrain obstacles. Based on the receiver’s approximate position, satellite visibility scenarios were generated using the developed platform. Static positioning was performed as part of the experiment, producing two sets of results: one using raw receiver observations without modifications, and the other incorporating visibility scenarios from the platform to adjust observation files. The tests were performed in 5 research scenarios. In each of the cases results demonstrated improvements in both accuracy and the success rate of position determination. For success rate, an increase of more than 20% was achieved. In many cases, positioning accuracy improved by more than 50%.