The estimation of GPS multipath error using dual-frequency carrier phase data

Multipath signal propagation is a major error source for precise Global Navigation Satellite System (GNSS) positioning. It is very important to obtain information about the possible multipath sources in positioning and the corresponding errors in the range and phase measurements. Global Positioning System (GPS) double-difference carrier-phase data are biased by an integer number of cycles. Resolving the GPS carrier-phase ambiguities has been a continuing challenge for GPS positioning.;This thesis introduces a method that enables very fast integer least-squares estimation of the ambiguities. Once the integer ambiguities are fixed correctly, the multipath errors are taken out from the psuedorange measurements and then it is possible to achieve high-precision positioning solutions.;Real data are downloaded in order to calculate the multipath error for long term observations. This thesis focuses on calculate of integer ambiguities by using the least squares method. Double difference technique is used to obtain the float solution for the ambiguities, and a MATLABRTM program has been implemented to find the fixed solution.