Cellular/satellite communications system with improved frequency re-use
First Claim
1. A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:
- downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals;
multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; and
modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station;
wherein said downconverting means comprise quadrature downconverting means producing an I and a Q baseband signals.
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Abstract
A satellite communications system employs a multiple element antenna for receiving signals on a first frequency band and relaying the signals to a ground station on a second frequency band. The system includes a downconvertor for converting signals received at each of the multiple antenna elements on the first frequency band to corresponding baseband signals, and a multiplexor for time-division multiplexing the corresponding baseband signals to form a multiplexed sample stream. The system also includes a modulator for modulating a carrier in the second frequency band with the multiplexed sample stream and transmitting the modulated carrier to the ground station. In exemplary embodiments, the downconvertor comprise a quadrature downconvertor producing an I and a Q baseband signal. The satellite relays signals received from the ground station using a demultiplexor in a similar manner.
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Citations
39 Claims
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1. A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:
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downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals; multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; and modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station; wherein said downconverting means comprise quadrature downconverting means producing an I and a Q baseband signals. - View Dependent Claims (2, 3, 4, 5, 6, 33)
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7. A satellite communications system for relaying signals received from a ground station on a second frequency band by transmitting said signals on a first frequency band using a multiplicity of antenna elements, including:
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downconverting means for converting signals received at said second frequency to a corresponding baseband signal; demultiplexing means for time-division demultiplexing said corresponding baseband signal to obtain separate sample streams; separate modulator means corresponding to each of said separate sample streams for directly receiving said separate sample streams and for modulating a carrier at said first frequency band with said separate sample streams to generate corresponding modulated signals; transmit amplifier means for amplifying said modulated signals and transmitting said modulated signals using said multiple antenna elements; wherein said downconverting means comprises a quadrature downconverting means producing an I and a Q baseband signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 34)
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15. A bidirectional satellite communications system comprising:
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a satellite including; a multiple element antenna having multiple antenna elements for receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band; downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals; multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; and modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station and a ground station including; downconverting means for converting signals received at said second frequency to a corresponding baseband signal; demultiplexing means, for time-division demultiplexing said corresponding baseband signal to obtain separate sample streams; modulator means for modulating a carrier with signals to generate corresponding modulated signals; transmit amplifier means for amplifying said modulated signals and transmitting said signals to said satellite; and wherein said multiplexing means and said demultiplexing means are synchronized. - View Dependent Claims (14, 16, 17, 18, 19, 20, 21, 22, 35)
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23. A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:
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downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals; multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; and modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station; wherein said multiplexing means comprises an I-signal multiplexing means and a Q-signal multiplexing means. - View Dependent Claims (36)
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24. A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:
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downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals; multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; and modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station; wherein said modulator means comprises a quadrature modulator means in which an I signal and a Q signal are impressed on respective carrier signals of nominally 90 degrees phase difference. - View Dependent Claims (37)
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25. A satellite communications system for relaying signals received from a ground station on a second frequency band by transmitting said signals on a first frequency band using a multiplicity of antenna elements, including:
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downconverting means for converting signals received at said second frequency to a corresponding baseband signal; demultiplexing means for time-division demultiplexing said corresponding baseband signal to obtain separate sample streams; separate modulator means corresponding to each of said separate sample streams for directly receiving said separate sample streams and for modulating a carrier at said first frequency band with said separate sample streams to generate corresponding modulated signals; transmit amplifier means for amplifying said modulated signals and transmitting said modulated signals using said multiple antenna elements; wherein said demultiplexing means comprises an I-signal demultiplexing means and a Q-signal demultiplexing means and said separate sample streams comprise I and Q sample streams. - View Dependent Claims (38)
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26. A communications system employing a satellite having a multiple element antenna having multiple antenna elements for receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:
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satellite downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals; satellite multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; satellite modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station; ground station receiving means for receiving said multiplexed sample stream from said satellite modulator means; ground station demultiplexing means for time-division demultiplexing said multiplexed sample stream to form separate sample streams; and ground station routing means for routing said separate sample streams to appropriate destination terminals. - View Dependent Claims (27, 28, 29, 30, 31)
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32. A satellite communications system employing a multiple element antenna receiving signals on a first frequency band and relaying said signals to a ground station on a second frequency band including:
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downconverting means for converting signals received at each of said multiple antenna elements on said first frequency band to corresponding baseband signals; multiplexing means for directly receiving and time-division multiplexing said corresponding baseband signals to form a multiplexed sample stream; modulator means for modulating a carrier in said second frequency band with said multiplexed sample stream and transmitting said modulated carrier to said ground station; and a time-division demultiplexing means for processing time-division multiplexed signals received from said ground station, wherein said demultiplexing means and said multiplexing means use a same clock. - View Dependent Claims (39)
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Specification