DORIS and its companion DIODE: a dedicated system for orbit determination

Summary form only given, as follows. The Centre National d'Etudes Spatiales (CNES) has developed an orbitography system called DORIS. From a network of about 50 ground beacons, the onboard receiver measures the Doppler effects. Such a system is currently performing on the French SPOT2 and SPOT3 imagery satellites. DORIS plays a fundamental role in the TOPEX/POSEIDON orbit computation with an accuracy of a few centimeters. A real time onboard orbit determination device named DIODE will be added to the following receivers. It is based on a Kalman filtering of the dense coverage tracking measurements on a 1750 computer using mainly ADA language. DORIS and DIODE will be on SPOT4, TPFO and ENVISAT satellites.<
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