| Summary: | The Global Positioning System (GPS) has been used for more than a decade for the
accurate determination of position on the earth's surface, as well as navigation. The
system consists of approximately thirty satellites, managed by the US Department of
Defense, orbiting at an altitude of 20 200 kilometres, as well as thousands of stationary
ground-based and mobile receivers. It has become apparent from numerous studies that
the delay of GPS signals in the atmosphere can also be used to study the amosphere,
particularly to determine the precipitable water vapour (PWV) content of the troposphere
and the total electron content (TEC) of the ionosphere.
This dissertation gives an overview of the mechanisms that contribute to the delay of
radio signals between satellites and receivers. The dissertation then focuses on software
developed at the Hartebeesthoek Radio Astronomy Observatory's (HartRAO's) Space
Geodesy Programme to estimate tropospheric delays (from which PWV is calculated) in
near real-time. In addition an application of this technique, namely the improvement of
tropospheric delay models used to process satellite laser ranging (SLR) data, is
investigated. The dissertation concludes with a discussion of opportunities for future
work. === Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2004.
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