Medium earth orbit satellite surveillance system and antenna configuration therefore
First Claim
1. A surveillance system for observing locations on the earth comprising:
- a plurality of medium earth orbit satellites, each satellite having an antenna having;
a main reflector having a first focal point;
a subreflector having a second focal point and electromagnetically coupled to said main reflector;
a phased array generating an electromagnetic beam positioned so the electromagnetic beam reflect from said subreflector so that some spillover occurs at a top portion of said main reflector.
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Abstract
A radar surveillance system includes a plurality of satellites a plurality of medium earth orbit satellites to provide continuous, long dwell coverage of a region of interest. Each satellite has an antenna having a main reflector and a subreflector electromagnetically coupled to the main reflector. A phased array generates multiple electromagnetic beams positioned so the electromagnetic beams reflect from the subreflector onto said main reflector. The system may be used in determining slow moving targets using a combination of monopulse anomaly and target spectral width measurements. The system also performs synthetic aperture radar imagery and focussed area fast moving target detection using alternating slope linear frequency modulated pulses. The plurality of medium Earth orbit satellites include a self-contained communications system consisting of high bandwidth self-relay crosslinks, high bandwidth downlink, and direct broadcast downlinks for processed data.
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Citations
19 Claims
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1. A surveillance system for observing locations on the earth comprising:
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a plurality of medium earth orbit satellites, each satellite having an antenna having;
a main reflector having a first focal point;
a subreflector having a second focal point and electromagnetically coupled to said main reflector;
a phased array generating an electromagnetic beam positioned so the electromagnetic beam reflect from said subreflector so that some spillover occurs at a top portion of said main reflector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 12)
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9. An antenna for a satellite comprising:
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a main reflector having a first focal point;
a subreflector having a second focal point, and a electromagnetically coupled to said main reflector;
a phased array generating an electromagnetic beam positioned so the electromagnetic beam reflect from said subreflector so that some spillover occurs at a top portion of said main reflector. - View Dependent Claims (10)
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11. A satellite comprising:
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a satellite body;
a surveillance antenna coupled to said satellite body;
a bidirectional downlink/uplink antenna coupled to said satellite body;
a plurality of high bandwidth radio frequency or optical crosslinks coupled to said satellite body;
a high bandwidth downlink antenna coupled to said satellite body;
a medium bandwidth directed broadcast downlink coupled to said satellite body; and
,a low bandwidth uplink receiver coupled to said satellite body.
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13. A method for detecting moving targets comprising steps of:
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establishing a discrete threshold;
obtaining a sum signal;
comparing the sum signal to the discrete threshold;
when the sum signal exceeds the discrete threshold, determining a monopulse anomaly;
when a monopulse anomaly is determined, classifying the signal as a stable mover;
when a monopulse anomaly is not found, statistically determining surrounding cells of an image to determine a power associated with interference or a discrete;
when the power ratio is low, the cells are classified as interference or a discrete;
when the power is high, classifying as an unstable mover. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification