Use of global ionospheric maps for precise point positioning: Developing an optimised procedure in using Global Ionospheric Maps for single-frequency standalone positioning with GPS

GPS-transmitted waves are affected by the Earth's atmosphere resulting in a decrease of the measured position accuracy. The highest region of the atmosphere, known as the ionosphere, is the main cause of this accuracy degradation. Due to the dispersive nature of the ionosphere for GPS-signals, the induced delay can be measured or eliminated if a dual-receiver is used. (By constructing the Geometry/Ionosphere-free Linear Combination, respectively). If a single-frequency receiver is used instead, one is obliged to account for the ionospheric delay in other ways. In this thesis is investigated how Global Ionospheric Maps (GIMs) can be used to correct for the ionospheric delay. Because these GIMs provide vertical ionospheric delays on given gridpoints and at discrete time-epochs, several processing steps have to be carried out: a spatial- and temporal-interpolation has to be performed to obtain an ionospheric delay estimate at the desired location and time and, subsequently, a mapping function has to be applied to transform the (interpolated) vertical value into the desired slant value. The objective of this research is to investigate the contribution of these processing steps to be able to develop an optimised procedure in using GIMs.With a stochastic analysis, in which GIM-based ionospheric delay estimates are compared with real measured ionospheric delays, a best-suited procedure in using GIMs is found. This optimised procedure is finally implemented into a single-frequency Precise Point Positioning (PPP) concept. Static observations reveal a position accuracy at the three-decimetre level horizontally and at the five-decimetre level vertically, for the European region.Aerospace Engineerin