<h2>AAS 95-334</h2><h2>Designing Clusters of Satellites for Radiolocalisation Purposes</h2><h4>E. Frayssinhes and E. Lansard,  ALCATEL ESPACE, TOULOUSE CEDEX, FRANCE</h4><h2> Abstract </h2>High precision localization of beacon positions is achieved by means of an innovative satellite system:  a cluster of satellites.  Each satellite measures the time-of-arrival of the signal transmitted by the beacon.  The derived time-differences-of arrival are processed to estimate the beacon position.  This paper investigates the localization accuracy with respect to the cluster geometry.  For that purpose, we propose a mathematical formulation relying on a strong analogy with GPS geometrical characterization of navigation performances.  This formulation is applied to design the optimal geometry of a cluster made of three LEO satellites, and to assess the impact of its short-term evolution on the localization accuracy.  Correlative problems dealing with the relative localization and synchronization of the satellites are also addressed.
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