A Multi-Base-Station Approach for Long Range Differential GNSS Positioning of Airborne Sensors

In airborne applications (e.g. photogrammetry, gravimetric measurements and laser scanning) the positions of the sensors are determined by Global Navigation Satellite Systems (GNSS). Traditionally, this has been done with differential techniques using GNSS observations from one reference station only. The distance and height dependent errors may be significant in airborne differential positioning using one reference station only. In this work the alternative approach of Multi-Base-Station (MBS) differential processing is discussed and verified. In the MBS approach, data from a network of permanent reference stations are used to estimate the distance dependent errors. Improved reference data can be materialized as e.g. observations from a Virtual Reference Station (VRS). Results from a test flight over a dedicated test field in Fredrikstad, Norway, are presented. Reference positions are estimated using photogrammetric aerial triangulation and compared to the positions from various GNSS processing strategies. The results verify that the method of Multi-Base-Station processing gives significantly more precise and reliable results than the traditional approach using one base station only.