ABSTRACT
Permanent observations GNSS implemented by large-area satellite network have been transformed into complex data communication system. They have offered not only post processing GPS services but also the provision of the correction data sent at real time. The first stages of their development were national passive systems created at the beginning of the 1990s, also in Poland [Baran L. 1994]. They have evolved from single reference stations located at technical universities to national systems. They were characteristic of autonomous station, lack of standardization within the range of unified report data replacement exploitation and local character of use [Dziewicki M. et al 1998]. As time passed by, passive systems gained differential function (GPS) of real time, becoming active structures - making DGNSS services possible. Meaningful broadening zone action, similar to nautical DGPS system, was connected with new telegram type RTCM [RTCM 2004b].
