Differential GPS (DGPS) technique is one of the most popular and accurate techniques to enhance GPS positioning accuracies by minimizing most of the common mode errors as a collective process. Several DGPS processing algorithms can also be used, for instance, single differencing and double differencing which are very common in practice. Irrespective of the DGPS processing algorithms used, the ultimate accuracy of the user location depends on the existence of non-common mode (site-dependent) errors, which occur at both sites; the points of observation and at the reference. Of these, the most common site-dependent error is the multipath. This book evaluates the potential of applying wavelets transform to C/A code multipath mitigation at GPS reference stations, for improved differential GPS corrections. This book can be recommended to students in surveying and all who want to have a look to basics of GPS, wavelet transformation and a special emphasis is put on the C/A code multipathmitigation based on wavelet transformation.