Performance evaluation of low-cost GPS systems for static and kinematic applications

This thesis looks at improving positional accuracy of low-cost systems by investigating a method to isolate the multipath error based on wavelet analysis. Several sets of static and kinematic data were collected in different types of environment using a single-frequency GPS receiver. The code minus carrier combination of the GPS observables was exploited. After accounting for certain errors and resolving the ionospheric delay using ionospheric maps, the remaining terms were essentially multipath and noise. Wavelet analysis was then used to extract the multipath error. These approximations were utilized to identify and remove those satellites that were severely contaminated with multipath. Another approach investigated the subtraction of multipath approximations obtained by wavelet analysis from the corresponding code measurements. The positioning results of these two approaches were compared with those of the original data and assessed. For the static data sets, eliminating satellites contaminated with multipath proved to be most effective. For the kinematic sessions, neither of the two approaches displayed any improvement.