Research On GPS Multi-Path Effects On Deformation Monitoring

GPS has revolutionized the science of positioning and Earth measurement. One is the accuracy, the other is the speed and simplicity, and the third is the cost. Additionally, it can provide 24 hours a day instantaneous global navigation and positioning service. All of these improvements are contributing to the growth of major applications. Presently GPS technique has not only been widely used for geodetic surveying but also for deformation monitoring, such as dams, bridges, engineer construction. Recently, GPS was used widely in the high precise vibration monitoring, it played an important part in keeping the safety of the buildings.This paper elaborated the realistic meaning of the research and summarized the international multipath processing methods and their merits and shortcomings firstly;secondly, analyzed the signal characteristic of the multipath and provided a multipath processing method based on the wavelets analysis and the FIR filter design according to the frequency;in the end, compared the multipath effect from the two methods and got satisfied result through an example. The main research contents of this paper are as follows:1, Setting out from mathematics angle, used functions to express the GPS multipath and analyzed its signal characteristics 2, According to GPS multipath signal characteristic, provided a max correlation coefficient multipath processing method based on the wavelets filter. The main questions of the wavelets analysis were the selection of the wavelets base and the decomposition level. This paper makes use of the max correlation coefficient to confirm the decomposition level according to the highest correlation between the continuous day multipath. The single epoch monitoring coordinate series' wavelets filtering validated the feasibility of this method.3n According to the low frequency characteristic of the multipath, put forward a data processing method based on the FIR filter design. When analyzed the method, firstly introduced the course of the filter design, containing the cut off of the frequency n the order of the filter and the window function;secondly, used the designed FIR filter to distill the multipath from the single epoch monitoring coordinates. In the end, an example verified the validation of the method.4n Finally, compared the multipath effort between the wavelets analysis and the FIR filter design. From the covariance of the corresponding day's multipath and the filtered coordinates, the result was consistency. The filtered coordinate, not only the mean but also the mean square root are better than the original coordinate series, this explained the success of the two methods.