SDARS-Antenna-Diversity-Schemes for a better Radio-Link in Vehicles

The most challenging task for digital mobile satellite broadcast reception is to satisfy a variety of combined requirements for automotive applications. According to the US satellite digital broadcast system (SDARS) the antenna parameters according to the SDARS-Antenna Specification have to be met [1]. There is a great desire for a low profile design or even hidden antenna systems according to styling conditions given by the Automotive Industry. For the time being there are strong recommendations for a specific mounting location of a SDARS-antenna in order to meet the required radiation pattern on a vehicle. For many vehicle models this location is considered as inconvenient and there is a strong demand to design more inconspicuous antennas. This design constraint for the SDARS antennas would cause intolerable high bit-error-rates resulting in too many interruptions in poor signal areas even though up to two QPSK-modulated satellite signals and a terrestrial OFDM-modulated signal of the digital data stream are made available at a time however with an offset of time between each other. The intention of this paper is to present research results with respect to the additional obtainable improvement by means of a fast switching antenna-diversity system in addition to the SDARS combined satellite-and-terrestrial-channel-diversity-system. Error correcting codes by principle are applied in any digital communication system but due a different character cannot be a substitute for the satellite-and-terrestrial-channel-diversity and antenna-diversity as well.