Advanced Signal Processing Techniques in Local User Terminals for Search & Rescue Systems Based on MEO Satellites

C. Fernández Prades, P. Closas and J. A. Fernandez Rubio

Abstract:	Cospas-Sarsat is a satellite-based system designed to provide distress alert and location data to facilitate Search and Rescue (SAR) tasks in an emergency situation, such as plane collision or boat sinking. When an emergency locator beacon is activated, it emits a signal which is relied by a set of satellites to a ground receiver, named Local User Terminals (LUT), in charge of processing the incoming signal replicas and determining the beacon position via Frequency and Time Difference of Arrival (FDOA and TDOA) techniques. Since mid-eighties, the system is using a constellation of 4 Low Earth Orbit (LEO) satellites and 3 Geostationary Earth Orbit (GEO) satellites demonstrating its reliability and usefulness, but improvements can be obtained in the user location estimation by using a constellation of Medium Earth Orbit satellites which is expected to increase accuracy, availability and reliability, among other capabilities. Mainly, there are two MEO constellations which are intended to host the Search and Rescue transponders: GPS and Galileo satellites, constituting the Distress Alerting Satellite System (DASS) and SAR/Galileo respectively. This work deals with the design of ground receiver stations in those cases. A complete study of the system has been done focusing on the parameter estimation problem under poor Carrierto- Noise ratios (C/N0), provided that tight power restrictions are foreseen in MEO based constellations.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	1349 - 1360
Cite this article:	Prades, C. Fernández, Closas, P., Rubio, J. A. Fernandez, "Advanced Signal Processing Techniques in Local User Terminals for Search & Rescue Systems Based on MEO Satellites," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 1349-1360.
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