Wide area high resolution SAR from a moving and hovering helicopter
First Claim
1. A radar system configured to acquire a synthetic aperture image of a target, said radar system comprising:
- a radar transmitter affixed to a hovering platform that transmits radar pulses;
a reflector moving relative to said hovering platform, said radar transmitter, and said target along a path, said reflector reflecting said radar pulses from said transmitter to said target as said reflector moves along said path, said radar pulses timed to generate said synthetic aperture image from radar returns from said target,wherein said synthetic aperture image is generated from said radar returns without any relative motion between said hovering platform and said target.
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Accused Products
Abstract
A hovering helicopter has a radar transmitter/receiver for transmitting radar pulses for illuminating a target for SAR imaging, and rotor blades for generating lift. Radar reflectors are on the rotor blades. The radar reflectors are oriented to reflect the radar pulses from the transmitter to the target as the rotor blades rotate. The radar pulses reflected by the moving reflector from the transmitter are timed to generate the synthetic aperture image using radar returns from the target. The receiver also receives blade returns directly reflected from the moving reflectors attached to the lift rotor blades. The receiver analyzes the blade returns to extract motion details of the reflectors and uses the motion details for motion compensation of target returns for SAR imaging.
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Citations
42 Claims
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1. A radar system configured to acquire a synthetic aperture image of a target, said radar system comprising:
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a radar transmitter affixed to a hovering platform that transmits radar pulses; a reflector moving relative to said hovering platform, said radar transmitter, and said target along a path, said reflector reflecting said radar pulses from said transmitter to said target as said reflector moves along said path, said radar pulses timed to generate said synthetic aperture image from radar returns from said target, wherein said synthetic aperture image is generated from said radar returns without any relative motion between said hovering platform and said target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A helicopter configured to acquire a synthetic aperture image of a target, said helicopter comprising:
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a transmitter fixed to a body of said helicopter configured to transmit radar pulses that illuminate said target; rotor blades, said rotor blades rotating with respect to said body and said transmitter so as to generate lift for said helicopter; and one or more reflectors on said rotor blades, said one or more reflectors oriented to reflect said radar pulses from said transmitter to said target; wherein said radar pulses are timed to generate said synthetic aperture image from radar returns from said target. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method configured to acquire a synthetic aperture image of a target using a radar system, the method comprising:
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transmitting radar pulses from a radar transmitter affixed to a non-rotating section of a hovering platform; illuminating a moving reflector with said radar pulses, said moving reflector moving along a path, said moving reflector reflecting said radar pulses from said transmitter to said target as said moving reflector moves along said path, said radar pulses timed to generate said synthetic aperture image from target returns from said target, wherein said synthetic aperture image is generated from said radar returns without relative movement between said hovering platform and said target. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of operating a hovering helicopter configured to acquire a synthetic aperture image of a target, the method comprising:
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transmitting radar pulses from a transmitter fixed to a body of said hovering helicopter; rotating rotor blades that generate lift for said helicopter; illuminating one or more reflectors on said rotating rotor blades with said transmitted radar pulses, said one or more reflectors oriented to reflect said transmitted radar pulses from said transmitter to said target as said rotor blades rotate; timing said transmitted radar pulses reflected by said one or more reflectors to generate said synthetic aperture image from target returns from said target. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A helicopter configured to acquire a synthetic aperture image of a target, said helicopter having a longitudinal axis, said helicopter moving with forward motion along said longitudinal axis, said target aligned with said forward motion along said longitudinal axis, said helicopter comprising:
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a transmitter fixed to a body of said helicopter that transmits radar pulses that illuminate said target; rotor blades that rotate to generate lift for said helicopter; one or more reflectors on said rotor blades, said one or more reflectors oriented to reflect said radar pulses from said transmitter to said target, said radar pulses timed to generate said synthetic aperture image from target returns from said target, wherein said target is aligned with said forward motion along said longitudinal axis of said helicopter while said synthetic aperture image is generated. - View Dependent Claims (32, 33, 34, 35, 36)
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37. A method for acquiring a synthetic aperture image of a target using a helicopter, said helicopter having a longitudinal axis, said helicopter moving with forward motion along said longitudinal axis, said target aligned with said forward motion along said longitudinal axis, said method comprising:
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transmitting radar pulses from a body portion of said helicopter to illuminate said target; rotating rotor blades of said helicopter to generate lift for said helicopter, said rotor blades equipped with one or more reflectors, said one or more reflectors oriented to reflect said radar pulses from said transmitter to said target; timing said radar pulses from said transmitter to said target as said rotor blades rotate to generate said synthetic aperture image from radar returns received from said target. - View Dependent Claims (38, 39, 40, 41, 42)
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Specification