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Both the group and phase velocity of the signals of all space geodetic techniques operating in the microwave band, is disturbed when they pass through the ionosphere – an effect, which can be corrected only if the measurements are carried out at two distinct frequencies. In this way also information about the parameters of the ionosphere in terms of Total Electron Content (TEC) values can be gained and used to correct single-frequency measurements and to monitor the ionization processes. The classical input data...

In the upper part of the EarthВґs atmosphere, the ionosphere, the free-electron and ion density is high enough to influence the propagation of electromagnetic waves. The ionosphere is a dispersive medium for the observables of all space geodetic techniques operating in the microwave band and disturbs both, their group and phase velocity. The effect is in first approximation proportional to the so-called Slant Total Electron Content (STEC) along the ray path and can be corrected if the measurements are carried out ...

The ionosphere is the upper part of the Earth atmosphere, starting at an altitude of about 50 km. It consists of free electrons and ions, mainly generated through solar radiation. GPS observations are delayed within the ionosphere, since it is a dispersive medium for electromagnetic waves. The range error caused by the ionosphere at the GPS operation frequency L1 can reach a few tens of meters. This effect is as a first approximation proportional to the so-called Slant Total Electron Content (STEC) along the ray p...