| This dissertation presents a novel way of using measurements made by satellite-based ranging systems, such as GPS, for the purposes of precise positioning. Traditional methodologies and assumptions are discarded, resulting in a view of code and carrier phase measurements as simple spatial distances in a three-dimensional trilateration network of extremely large extent. Although the example navigation system used is GPS, the findings have general applicability to all Global Navigation Satellite Systems, such as GLONASS and GALILEO.; Traditional dependence on the single, fixed base station for GPS processing is eliminated by investigation of the underlying datum problem and an improved method based on the constraint of the network centre of mass is presented. This strategy has advantages in terms of minimally-biased ambiguity solution and positioning accuracy homogeneity across the network.; A novel approach to variance-covariance modelling for GPS error sources is developed, which separates the total error in terms of noise, multipath and tropospheric and ionospheric errors and models each individually. The models are developed using theoretical considerations coupled with empirical determination of key model parameters. Temporal and inter-frequency correlations are discussed as well.; The results of the research were used to create a GPS processing system named PADRES-GPS. It was shown that this system is capable of effectively detecting deformations of 10 mm at the 95% level on small-extent networks when data spans of only 10 minutes were used. The availability of the position solutions was shown to be much higher than that achievable by a commercial processing package due to the application of a novel “partial-fix” approach to ambiguity resolution documented herein. The PADRES-GPS system was also shown to improve positioning on larger networks extents via modelling of spatial correlations. Finally, a method of compressing dual-frequency data into a single optimal linear combination is described and its performance in kinematic network positioning is demonstrated. |
