System for maintaining polarization and signal-to-noise levels in received frequency reuse communications
First Claim
1. A movable system for receiving staggered frequency reuse communications from a referentially fixed source, said system comprising:
- a controllable antenna for receiving said frequency reuse communications from the source; and
adaptive polarization tracking means for maintaining a desired polarization of the communications received by said antenna.
1 Assignment
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Accused Products
Abstract
In a preferred embodiment, the disclosed system is part of a communication system (10) formed by a satellite (12) and aircraft (14). The system includes a controllable antenna network (16) and polarization tracking network (18). The controllable antenna network includes an array (28) of orthogonal antenna pairs (34) whose beams are steerable by phase shifters (46) to correct for changes in the aircraft'"'"'s attitude. Similarly, amplifier circuits (44) compensate for changes that would otherwise occur in the signal-to-noise ratio of the antenna'"'"'s output. The polarization tracking network includes a forward section (62), defined by quadrature hybrids (66) and (70) and an adjustable phase shifter (68), and a feedback section (64) that monitors each polarity for the presence of a single select channel. The phase shifter responds to the comparison made by a phase detector (86) in the feedback section to maintain the desired polarization of all channels.
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Citations
25 Claims
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1. A movable system for receiving staggered frequency reuse communications from a referentially fixed source, said system comprising:
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a controllable antenna for receiving said frequency reuse communications from the source; and adaptive polarization tracking means for maintaining a desired polarization of the communications received by said antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An adaptive polarization tracking network for maintaining a desired polarity between a first polarized signal defining a first set of information channels and a second polarized signal defining a second set of information channels, said network comprising:
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monitor means for monitoring the first and second polarized signals and producing an output indicative of the presence of a select information channel on each; and null means, responsive to said output of said monitor means, for nulling the select information channel on one of the first and second polarized signals to maintain the desired polarity therebetween. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A steerable antenna system comprising:
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a steerable antenna for receiving electromagnetic radiation and producing a signal in response thereto; and means for maintaining a substantially maximized signal-to-noise ratio for said signal as said antenna is steered, including; a first quadrature hybrid, having a first input port and first and second output ports, said antenna being coupled to said first input port, said first hybrid being for dividing said signal produced by said antenna equally between said first and second output ports; a pair of low-noise amplifiers, coupled to said first and second output ports, for amplifying said signal divided between said first and second output ports; and a second quadrature hybrid, having first and second input ports, coupled to said pair of low-noise amplifiers, and a first output port, said second quadrature hybrid being for summing said signal divided by said first hybrid and amplified by said amplifiers to produce a system output. - View Dependent Claims (22)
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23. A method of receiving frequency reuse communications at a site that is relatively movable with respect to a source of the communications, comprising:
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steering an antenna system to maintain an antenna beam directed toward said source as the site and source undergo relative motion and receive the frequency reuse communications; and adaptively correcting the polarization of the frequency reuse communications received by the antenna system to maintain a desired polarization as the site and source undergo relative motion.
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24. A method of maintaining a desired polarity between first and second sets of channels received from a frequency reuse communication source, comprising the steps of:
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monitoring the first set of channels for the presence of a select channel that is present in the first set unless the desired polarity is achieved; and nulling the select channel present in the first set of channels when its presence is monitored.
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25. A method of receiving frequency reuse communications at a site that is relatively movable with respect to a source of the communications, comprising:
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steering an antenna system to maintain an antenna beam directed toward said source as the site and source undergo relative motion and receive the frequency reuse communications; and processing the frequency reuse communications received by the antenna system to maintain a substantially maximized signal-to-noise ratio as the site and source undergo relative motion.
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Specification