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Over the past 18 months, a team in the Western Australian Centre for Geodesy at Curtin University of Technology, Perth, has been researching the optimum configurations to achieve long-range and precise GPSbased aircraft positioning for subsequent airborne mapping projects. Three parallel strategies have been adopted to solve this problem: virtual reference stations (VRS), precise point positioning (PPP), and multiple reference stations (MRS). This paper briefly summarises the concepts behind the PPP and VRS techniques, describes the development and testing of in-house software, and presents the latest experimental results of our research. Current comparisons of the PPP and VRS techniques with an independently well-controlled aircraft trajectory and ground-based stations in Norway show that each deliver precisions of around 3 cm. However, the implementation of more sophisticated error modelling strategies in the MRS approach is expected to better deliver our project's objectives.

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-Automatic estimation of traffic parameters has evolved to an important topic of research. Current and upcoming SAR satellite missions offer new possibilities for traffic monitoring and control from space as an alternative to conventional traffic data acquisition. In this paper a detection approach is presented which evaluates simultaneously the effects moving objects suffer from in the SAR focusing process. Information about the measured signal and the expected signal are utilized in the detection framework. Analyses of the proposed technique are done with real spaceborne SAR data.