Based On Wavelet Transform Of The Multipath Errors

Because GPS survey possess a capability of high precision and three dimensional positioning, it becomes an extremely effective tool for a variety of deformation monitoring, but the GPS measuring is effected by some error sources, while the multi-path error is closely related to environment, and can not be weakened by differential technique effectively, so multi-path error becomes the main error in high precision deformation monitoring. Wavelet transform is known as "mathematics microscope", which is a very effective mathematical method in signal analysis and processing, has advantages that other methods unparalleled.Above all, the paper discusses the background and significance of multi-path error in deformation monitoring, introduces some error sources of GPS, wavelet analysis theory and applications of wavelet in surveying and mapping , explores the applications of wavelet transform in the signals; Second, according to the generation principle of multi-path, this paper analyses and summarizes the types of multi-path and the characteristics of multi-path effect, analyses the influences of the multi-path effect under the condition of one reflection source and several reflection sources; Third, the paper studies wavelet transform to extract multi-path error from the series of coordinates.During the research, first of all, this paper decides the selection of wavelet and the level of decomposing, and analyses the original coordinates; Second, the paper analyses a practical case using traditional algorithm , extracts multi-path error , filters the original coordinates and analyses the filtering effect, the result shows that the traditional algorithm can not extract the multi-path effect effectively, the algorithm needs to be improved; Third, because of the defects of traditional algorithm, author proposes a improved algorithm and diagram, and analyses a practical case using improved algorithm, extracts multi-path error from the original series of coordinates and filters the original coordinates, analyses the multi-path and the filtered coordinates; Finally, the paper compares and analyses multi-path error and filtered coordinates which using the traditional algorithm and improved algorithm, the analysis result shows that the improved algorithm can extract multi-path error effectively, can achieve the desired filtering effect.