A Global Navigation Satellite System (GNSS) software library called G-Nut has been devel oped at the Geodetic Observatory Pecný (GOP) since 2011. Several applications built of the library will be provided as an open source in 2013 and consequently users are able to modify source code and use it for processing their own data free of charge. The main purpose of the project is to create a programming package suitable for implementing various end-user a pplications such as kinematic position estimation, long-term permanent station coordinates monitoring, zenith tropospheric delay estimation, satellite clock estimation and others. The library is written in C++ programming language following the object-oriented concept. Basic class structure implementing inputs/outputs and product/d ata containers support both real-time and post-processing modes. Integration of all available global navigation satellite systems (GPS, GLONASS, Galileo, BeiDou, QZSS) as well as new tracking signals is properly handled. The configuration is governed through the XML format. The estimation model currently supports the least square adjustment, the Kalman and square root covariance filtering methods based on processing undifferenced data and fixed precise orbit and clock products. The estimated state vector includes receiver coordinates and clocks, troposphere zenith path delays and initial carrier phase ambiguities. The first applications based on G-Nut library are shown with examples for off-line/online kinematic/static precise point positioning and ultra-fast troposphere estimation., Pavel Václavovic, Jan Douša and Gabriel Györi., and Obsahuje bibliografické odkazy
The aim of this paper is the analysis of temporal changes in multipath propagation errors on the pseudorange GNSS signal used for positioning, and its behavior during the calendar year (the quality of signal depends on e.g. foliage of trees, changes reflectivity surfaces due to rain or snow, etc.). The analysis was performed on data measured on a stationary point at Geodetic Observatory Pecný at Ondřejov, where one day was chosen as a constant time unit. Given the relatively highly unfavorable configuration of the experiment, RMS value of multipath is up to 60 cm on C1 and 40 cm on C2. These values vary with different weather conditions between 10 and 20 cm.