HELICOPTER EMULATION OF ARCHIMEDES MEDIASTAR SATELLITE DAB TRANSMISSION TO MOBILE RECEIVERS/

In the framework of the Archimedes programme, the European Space Agenc y (ESA) has been studying the application of satellites in multi-regio nal highly inclined elliptical orbits (M-HEO) for digital radio and re lated multimedia services and for mobile communications. More recently , these studies led to a proposal for an operational satellite-based E UREKA-147 Digital Audio Broadcasting (DAB) system. ESA studies have sh own that an optimized satellite constellation of six HEO satellites in 8-h orbits could provide uninterrupted broadcast services in Europe, North America and East Asia with elevation angles significantly higher than those obtained with geostationary (GEO) satellites. The high ele vation angles result in considerably less signal shadowing and multipa th effects particularly in the case of mobile reception. Detailed chan nel characterization studies and performance analyses have demonstrate d the feasibility of a digital audio broadcasting satellite system bas ed on the European EUREKA-147 DAB standard. However, a number of uncer tainties remained concerning the characteristics of the transmission c hannel and the EUREKA-147 DAB performance under operational conditions . ESA therefore awarded a contract to the German Aerospace Research Es tablishment (DLR) supported by the Institut fur Rundfunktechnik (IRT), to perform a so-called Archimedes DAB Measurement and Verification Ca mpaign. The main objective of this campaign was the assessment of the EUREKA-147 DAB performance using a commercial receiver under a wide ra nge of representative, 'quasi-operational' conditions by appropriately selected objective and subjective measures. Because no HEO satellite was available for these measurements, a helicopter emulating as closel y as possible the characteristics of a HEO satellite was employed. The main results of the Archimedes DAB Measurement and Verification Campa ign are reported in this study. These results are not specific only to the Archimedes system. (C) 1997 by John Wiley gr Sons, Ltd.