Doppler Orbitography and Radiopositioning Integrated by Satellite
Doppler Orbitography and Radiopositioning Integrated by Satellite ( DORIS ) is a system of satellite geodesy that includes around 50 special ground stations. It is used to determine the exact orbit of satellite orbits with the help of the Doppler effect of radio signals. Due to the worldwide distribution of the satellite stations , the method also contributes to the modern global reference systems of the geosciences (see GNSS / GPS and IGGOS ) and to the ongoing monitoring of the earth's rotation .
DORIS is a further development of the Doppler satellite principle previously used by transit satellites . Compared to Transit, the way it works is the opposite, in that the high-precision radio signals are not radiated from the satellites, but from the ground stations on two frequencies. In the orbit, the signals are registered by special measuring units and their results are transmitted to earth. The technically complex data analysis takes place on the earth's surface. The use of two frequencies increases the measurement accuracy (similar to GPS ).
The system was developed by France around 1990 and requires only relatively little effort in the satellite, while the ground stations are integrated into a complex telemetry and surveying network. It achieves accuracies in the decimeter range and is therefore somewhat inferior to other methods such as GNSS or satellite laser ranging , but has the advantage of globally evenly distributed measurement data. It is therefore part of the international IUGG services and recognized as part of the ITRF system.
The measuring units can be built into satellites of various types and are u. a. integrated as accessories in the Envisat , Cryosat-2 and some altimetry satellites such as the Jason . DORIS can provide the global reference framework for regional and time-related measurement campaigns .
See also
literature
- G. Seeber: Satellite Geodesy . De Gruyter-Verlag, 2nd edition (590p.), Berlin 2003