GPS ve GLONASS gözlemlerinden çoklu değişim özellikleri

Global Navigation Satellite Systems (GNSS) that consist of GPS, GLONASS, BeiDou, QZSS, and Galileo have been widely used in navigation, positioning, geodesy, attitude determination, engineering survey and agricultural applications. A number of random and systematic errors like ionospheric delay, tropospheric delay, receiver noise and multipath affect GNSS observations. Most of these errors can be removed by differential techniques. However, multipath delays are independent of each receiver, which cannot be removed by difference. Therefore, multipath is a major error source in differential GNSS positioning. A number of techniques, e.g., notably narrow correlator technology and filtering, have been developed to mitigate multipath errors. In this thesis, the multipath of GPS and GLONASS are estimated and investigated using the linear combinations for both pseudo-ranges P1 and P2 and carrier phases L1 and L2 data with eliminating the effect of receiver and satellite clocks as well as the atmospheric delay from 3-year (2014-2016) GPS and GLONASS observables at 5 stations. These stations are respectively, DJIG station in Djibouti, DYNG station in Greece, MAL2 station in Kenya, MAYG station in Mayotte and SEYG station in Seychelles. Results are obtained in different years based on the multipath results and analysis. In 2014, the RMS-MP1 and RMS-MP2 values of the DYNG station were below the decimeter level in both systems. For the SEYG station, the RMS-MP1 value of GLONASS has a small multipath level of 0.02 meters, while the RMS values of GPS shows the highest multipath level of 0.14 meters. In 2015, the smallest RMS-MP1 value is the DYNG and the DJIG stations. The larger effect is the MAL2 station for the RMS-MP1 values of both systems. In 2016, the most affected station is the DJIG station . These multipath are the most related to the surrounding environments of the antenna.