Common direct broadcasting service system

摘要

The invention relates to a Common Direct Broadcasting Service (CDBS) system for a communications spacecraft. The CDBS system comprises N uplink antennas for receiving uplinks from terrestrial transmitting stations. Each uplink includes left-hand circular polarized (LHCP) signals and/or right-hand circular polarized (RHCP) signals. The LHCP signals and the RHCP signals have frequencies within predetermined channels of a first and/or second predefined frequency band. The CDBS system also comprises means for separating the LHCP signals of the uplinks received by each uplink antenna from the RHCP signals of the uplinks received by each uplink antenna. The CDBS system further comprises a plurality of receivers for converting the separated LHCP signals and RHCP signals of the uplinks to first signals and second signals, respectively, of the uplinks. The first and second signals have frequencies within channels of a third and/or fourth predefined frequency band. The CDBS system also includes means for selecting a predetermined number of the first and second signals of the uplinks, and means for down-selecting signals of the predetermined number of the first and second signals having frequencies within selected ones of the channels of the third and/or fourth predefined frequency bands. The CDBS system further comprises a plurality of downlink antennas for downlinking signals down-selected by the down-selecting means from the communications spacecraft to selected ones of the plurality of terrestrial receiving stations.