Comparison of tropospher models used in commercial GPS softwares

The Global Navigation Satellite System (GNSS) is one of the most important discoveries made by humanity in the history of measurement. GPS was established in 1974 and GLONASS in 1976 for military purposes. It was opened for civilian use in 1980 and 1982, respectively and started to be used in daily life. Today, it has become a system that is used at every stage of daily life and provides convenience to users. GNSS system is developing very fast in line with technological studies. These rapid developments have led scientists to develop new methods to meet the needs of users and to obtain the most accurate results. One of the best efforts to minimize the effect of GNSS signals in the atmosphere is to use dual frequency GNSS receivers. These receivers can eliminate the errors that the GNSS signals encounter in the ionosphere layer. However, they are not able to correct faults that occur in the troposphere layer. In order to eliminate these errors, it can minimize the tropospheric effect by measuring the humidity, temperature and pressure values at each measurement point and using these values in calculations. However, because this process will take a lot of time and is very costly, scientists have made tropospheric modeling. By using these models in GNSS software, the effect of the troposphere layer on signals can be minimized. In this study, four different measurement campaigns have been conducted to observe the effect encountered by GNSS signals under different atmospheric conditions of Troposphere models. Topcon Tools ver.7 and Leica Geo Office 7.0 were used to evaluate these campaigns. The effect of troposphere models on the calculations was observed in these softwares. The results were compared with the inclusion of the atmospheric values measured at the time of the session and the atmospheric values obtained from Turkish State Meteorological Service.