Repeaters for multibeam satellites
First Claim
1. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
- first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels;
means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams, wherein each said means for selecting and for dividing is connected to an output of an input demultiplexer and includes a frequency downconverter in series with a bank of surface-acoustic-wave filters;
second means for interbeam switching the subchannels produced by dividing the selected channels;
means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and
means for connecting the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs of the output multiplexers.
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Accused Products
Abstract
A repeater for a multibeam communications satellite combines the features of coaxial channel interbeam switching and subchannelization of some of the channels. In one embodiment described, the input radio-frequency signals from the input beams are fed through the input multiplexers to form channels. Some, but not all, channels are subsequently subchannelized for interbeam switching. In another embodiment of the invention, a portion of the incoming radio frequency signals bypasses the input demultiplexer and is filtered for noise-limiting reasons, converted down to an intermediate frequency and then subchannelized using SAW filters. The specification also teaches that digital techniques can be used to obtain the same results. Especially in the case of satellites with a large number of beams and a large number of channels, it is not necessary to have full interbeam switching of all the subchannels derived from one channel: instead, the specification proposes the use of parallel configurations of smaller, less complex switching networks.
69 Citations
17 Claims
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1. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
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first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels; means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams, wherein each said means for selecting and for dividing is connected to an output of an input demultiplexer and includes a frequency downconverter in series with a bank of surface-acoustic-wave filters; second means for interbeam switching the subchannels produced by dividing the selected channels; means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and means for connecting the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs of the output multiplexers.
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2. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
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first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels; means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams, wherein each said means for selecting and dividing is connected to an input of an input demultiplexer and includes, in series, a band-limiting filter, a frequency downconverter and a bank of surface-acoustic-wave filters; second means for interbeam switching the subchannels produced by dividing the selected channels; means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and means for connecting the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs of the output multiplexers.
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3. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications hand for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
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first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels; means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams, wherein each said means for selecting and dividing is connected to an input of an input demultiplexer and includes means for converting each selected channel to a digital format and digital multiplexer means to divide the converted selected channels into subchannels; second means for interbeam switching the subchannels produced by dividing the selected channels; means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and means for connecting the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs of the output multiplexers.
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4. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
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first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels; means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams; second means for interbeam switching the subchannels produced by dividing the selected channel, wherein said second means for interbeam switching comprises a solid-state switching network; means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and means for connecting the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs of the output multiplexers.
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5. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
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first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels; means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams; second means for interbeam switching the subchannels produced by dividing the selected channels, wherein said second means for interbeam switching comprises a matrix of GaAs FET devices; means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and means for connecting the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs of the output multiplexers.
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6. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams wherein the improvement comprises the combination of:
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first means for interbeam switching a plurality of the channels produced at the output of said input demultiplexers, thereby creating a set of interbeam-switched channels; means for selecting and for dividing into subchannels at least one channel from each of at least two of the incoming beams; second means for interbeam switching the subchannels produced by dividing the selected channels; means for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; and means for connecting the interbeam-switched channels and interbeam-switched subchannelized channels to the inputs of the output multiplexers, wherein said means for connecting includes a switch for selectively connecting either an interbeam-switched channel or an interbeam-switched subchannelized channel, to the input of an output multiplexer.
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7. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams, wherein the improvement comprises the combination of:
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a coaxial switching matrix connected to the outputs of said input demultiplexers for interbeam switching, at radio frequency, channels produced at the output of said input demultiplexers, thereby to create a set of interbeam-switched channels; frequency downconversion circuits connected to the input demultiplexers, each of said downconversion circuits downconverting the channels associated with an input beam to an intermediate frequency; a bank of surface-acoustic-wave filters connected to the output of each frequency downconversion circuit to divide, at an intermediate frequency, the channel into frequency-spaced subchannels; a solid-state matrix connected to the outputs of the banks of filters for interbeam switching the subchannels produced by the filter banks; a solid-state network for combining the interbeam-switched subchannels into a set of interbeam-switched subchannelized channels; frequency upconversion circuits connected to the outputs of the solid-state network to convert the set of interbeam-switched subchannelized channels to radio frequency; and connection circuitry, including amplifiers and filtering circuits, to connect the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs to the output multiplexers. - View Dependent Claims (8, 9)
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10. A communications repeater for a multibeam satellite in which a satellite radio-frequency communications band for each beam is comprised of a plurality of associated channels, each channel containing intelligence separable into distinct subchannels, said satellite repeater having an input demultiplexer for each incoming beam for dividing beams into channels and an output multiplexer for each outgoing beam for combining channels into beams, wherein the improvement comprises the combination of:
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a coaxial switching matrix connected to the outputs of said input demultiplexers for interbeam switching, at radio frequency, said channels produced at the output of said input demultiplexers, thereby to create a set of interbeam-switched channels; frequency downconverting circuits connected, through band-limiting filters, to the inputs of at least two input demultiplexers, said circuits downconverting the signals at the outputs of said band-limiting filters to an intermediate frequency, the down-converted signals representing at least two selected channels; a bandpass filter connected to the output of each frequency downconverting circuit and each connected to the input of a quadrature downconverter; each said quadrature downconverter connected to the output of the bandpass filter to convert the selected channel to baseband; first lowpass filters connected to the outputs of each quadrature downconverter; analog-to-digital converters for receiving the output signals from the first lowpass filters for converting the baseband signal to digital format; digital demultiplexers connected to the outputs of the analog-to-digital converters to divide the digital signals into subchannels, each subchannel being represented by a time slot; a digital switch connected to the outputs of the digital demultiplexers for routing the subchannels in their time slots to digital multiplexing circuits, said digital multiplexing circuits serving to combine the subchannels into a set of interbeam-switched subchannelized channels; digital-to-analog converters connected to the outputs of the digital multiplexing circuits for converting the interbeam-switched subchannelized channels to analog format; second lowpass filters connected to the output of said digital-to-analog converters for smoothing the digital-to-analog output signal and filtering of upper-frequency images; upconverting circuits for converting the outputs of the second lowpass filters to radio frequency; connecting circuitry, including amplifiers and filtering circuits, to connect the interbeam-switched channels and the interbeam-switched subchannelized channels to the inputs to the output multiplexers. - View Dependent Claims (11, 12)
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13. A communications repeater for use with a multibeam satellite, said repeater comprising:
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a plurality of input demultiplexers, wherein each input demultiplexer is connected to an input beam, and wherein each input demultiplexer separates the input beam into a plurality of channels; a coaxial switching network connected to some, but not all, of the plurality of channels, wherein said coaxial switching network switches the connected channels to form a set of interbeam-switched channels; a subchannelizing and solid state switching circuit connected to the plurality of channels which are not connected to the coaxial switching network, wherein the circuit separates the connected channels into subchannels, switches the subchannels, and forms a set of interbeam-switched subchannelized channels; a plurality of output demultiplexers, wherein each output demultiplexer is connected to at least one of the interbeam-switched channels and at least one of the interbeam-switched subchannelized channels, and wherein the output of each output demultiplexer forms an output beam. - View Dependent Claims (14, 15, 16)
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17. A communications repeater for use with a multibeam satellite, said repeater comprising:
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a plurality of input demultiplexers, wherein each input demultiplexer is connected to an input beam, and wherein each input demultiplexer separates the input beam into a plurality of channels; a coaxial switching network connected to the plurality of channels, wherein the coaxial switching network switches the channels to form a set of interbeam-switched channels; a filtering, subchannelizing and solid state switching processor connected to at least one of the input beams, wherein said processor includes narrow bandpass filters that filter the input beam into a representative channel, wherein said processor further includes separation circuitry that separates the filtered channel into subchannels, and wherein said processor further includes subchannel switches that switch the separated subchannels to form a set of interbeam-switched subchannelized channels; a plurality of channel switches, wherein each of said channel switches is connected to at least one interbeam-switched channel and at least one interbeam-switched subchannelized channel, and wherein the switch is used to selectively connect either the interbeam-switched channel or the interbeam-switched subchannelized channel onto the channel switch output; a plurality of output multiplexers, each output multiplexer connected to at least one of the interbeam-switched channels and at least one channel switch output, the output of each output demultiplexer forming an output beam.
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Specification