Quantitative estimation and modelling of GPS carrier phase multipath signals

Abstract

The Global Positioning System (GPS) has been shown to be capable of supporting a wide variety of exciting applications. However, multipath is a dominant error source that limits the widespread use of GPS in precise surveying operations such as deformation monitoring applications. This research observes the effects of carrier phase multipath signals based on site environments. A GPS multipath signal propagation model is presented. Visualization and the generation of multipath errors are provided. Estimated multipath error results are presented and further analyzed with the field data. By estimating and modelling of multipath signals, a better understanding of the characteristic of the multipath can be achieved. In this research, Electromagnetic (EM) modelling technique is described and used as the mathematical basis for quantifying and modelling of the carrier phase multipath error parameters, where the parameters' characteristics of the different multipath signals are handled separately. Both commercial and in-house software packages are used to facilitate the computations. Static multipath modelling studies are carried out in the field trials. Modelling of carrier phase multipath signals in a pre-defined controlled environment is first analysed. Further analysis of the propagation mechanisms of a site environment is investigated. Selected measured and estimated multipath error results are presented and compared for verification of the EM modelling technique. It can be seen from the results that the proposed method can provide very useful results for correcting and analysing GPS multipath errors.