Gps Precision Positioning Error And Phase Multipath Errors

In update precise engineering surveying areas, such as the deformation monitoring of dam, the protection of ancient building and the setup of precise equipment etc. It is demanded that the baseline precision is up to 0.5-2mm, on the other hand, the length of corresponding baseline is so short, most of them are shorter than 2km,some of them are only from ten of meters to hundreds of meters. So it is necessary to solve such a problem that how to satisfy the high precision demand to the short base by using precise GPS techniques.In the paper, firstly, the error recourses to GPS relative positioning esp. to the short or super short baseline positioning are analyzed. Secondly, the characters of errors and deflections of nowadays error processing theory are analyzed, and the methods to eliminate the effect by such errors are pointed out esp. the multipath the key error to short base positioning. Still, the mechanism characters and degree of multipath are analyzed in details. Thirdly, the development of method and their advantages and disadvantages to erase the multipath effect are analyzed.In this paper, the method to erase the multipath effect by using SNR is theoretical researched and practical realized. The concept of epoch difference is used to solve the unknown of antenna multiply figure, and to get the degree of multipath error by using Flourier transformation and nonlinear minimized square theory are analyzed, and good results are researched.