Investigation of the effect of GPS signal reflection on point positions

ABSTRACT GPS technique that was initially developed for military navigation purposes is now used widely in geodetic applications as well as in many fields of civil life. The all satellites has almost been achieved and with it increased use of the system has shown that in specific cases the accuracies reached may be inadequate. These error sources can be given as satellite and receiver clock errors, satellite orbit errors, ionespheric and tropospheric delay, multipath and receivers errors. The most of error sources can be minimised by the application of proper measurement techniques. But some of errors such as multipath can not be eliminated easily. Multipath errors occur if the received GPS signal is composed of the direct line of sight signal and one or more constituents which have propagated along paths of a different length. In this study the effect of multipath for point position is examined. For this purpose, two test networks are established. In the first test network to examine the effect of the F mode scatter, galvanized corrugated sheet metal is used. In the seccond test network to examine F mode scatter water surface is used. Collected GPS data for two test networks are processed by GAMIT/GLOBK software package. With this process WGS84 coordinates of test point are determined. With these coordinates the effect of multipath are examined. Keywords : GPS, Error Sources, Signal to Reflect, Multipath