Radar imaging via spatial spectrum measurement and MIMO waveforms
First Claim
1. A radar imaging system comprising:
- a transmit antenna divided into a plurality of array segments adapted to transmit a plurality of orthogonal radar waveforms to illuminate a target region extending in a range direction and in an azimuth direction;
a waveform generator capable of generating the plurality (N) of orthogonal waveforms concurrently for radar illuminations whereas N is a positive integer;
a receive antenna divided into a plurality of array segments, wherein the receive antenna is adapted to receive a radar return from the target region and to generate a plurality of return signals associated with corresponding ones of the plurality of array segments;
a post processing performing three functions on Radar return signals;
(1) synthesizing receiving beams, (2) generating virtual transmit beams, and (3) performing convention radar ranging and Doppler processing.
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Accused Products
Abstract
The proposed MIMO radar imaging method takes advantages of measurement techniques of spatial frequency components of an RF area image from radar returns. To minimize size, weight and power (SW&P), minimum redundancy arrays (MRAs) for both Tx and Rx with unique geometries are proposed. MIMO waveforms are utilized to index the radiated illuminations to a targeted area in the forms of 1-D spatial frequency components. Consequently, the corresponding radar returns from the targeted field of view (FOV) are captured by the Rx MRA. With the knowledge of uniquely designed MRA array geometries, virtual beams are synthesized in Rx processor; usually one Tx and many contiguous Rx fan beams. These virtual beams may be dynamically “moved” to different beam positions. The elongated beam direction for Tx fan beam and that for Rx fan beams are perpendicular to one another. Thus intersections of the Tx fan-beam and many Rx fan-beams are the very areas of radar returns. We refer those areas as virtual beam crosses. Conventional range and Doppler gating processing shall then be applied to the beam crosses concurrently. Radar return pixel-by-pixel within various beam crosses are measured individually. Radar images can then be synthesized.
MIMO radars via spatial spectrum measurements are well suited for wide angle surveillance via improved angle estimation and minimum detectable velocity. SDS proposed MIMO radar design concepts on moving platforms can be used for both the line-of sight (LOS) SAR/GMTI applications. For fixed Radar, they are applicable for fixed radars LOS target detection and tracking, or imaging. They may also be useful for OTH maritime target detection and tracking utilizing evaporation duct propagation
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Citations
38 Claims
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1. A radar imaging system comprising:
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a transmit antenna divided into a plurality of array segments adapted to transmit a plurality of orthogonal radar waveforms to illuminate a target region extending in a range direction and in an azimuth direction; a waveform generator capable of generating the plurality (N) of orthogonal waveforms concurrently for radar illuminations whereas N is a positive integer; a receive antenna divided into a plurality of array segments, wherein the receive antenna is adapted to receive a radar return from the target region and to generate a plurality of return signals associated with corresponding ones of the plurality of array segments; a post processing performing three functions on Radar return signals;
(1) synthesizing receiving beams, (2) generating virtual transmit beams, and (3) performing convention radar ranging and Doppler processing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A radar imaging system comprising:
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a transmit antenna divided into a plurality of array segments adapted to transmit a plurality of orthogonal radar waveforms to illuminate a target region extending in a range direction and in an azimuth direction; a waveform generator capable of generating the plurality (N) of orthogonal waveforms concurrently for radar illuminations whereas N is a positive integer; a receive antenna divided into a plurality of array segments, wherein the receive antenna is adapted to receive a radar return from the target region and to generate a plurality of return signals associated with corresponding ones of the plurality of array segments; a post processing performing three functions on Radar return signals;
(1) synthesizing receiving beams, (2) generating virtual transmit beams, and (3) performing convention radar ranging and Doppler processing. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A radar imaging system comprising:
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a transmit antenna divided into a plurality of array segments adapted to transmit a plurality of orthogonal radar waveforms to illuminate a target region extending in a range direction and in an azimuth direction; a waveform generator capable of generating the plurality (N) of orthogonal waveforms concurrently for radar illuminations whereas N is a positive integer; a receive antenna divided into a plurality of array segments, wherein the receive antenna is adapted to receive a radar return from the target region and to generate a plurality of return signals associated with corresponding ones of the plurality of array segments; a post processing performing three functions on Radar return signals;
(1) synthesizing receiving beams, (2) generating virtual transmit beams, and (3) performing convention radar ranging and Doppler processing. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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- 26. The waveforms injection network of the radar imaging systems comprising N-to-M passive architectures using two cascading functions of re-distribution and combining whereas the N is the number of input ports connecting to different orthogonal waveforms and M is the number of output ports connecting to various transmitting array segments.
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30. A radar imaging system on a moving platform comprising:
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a transmit antenna divided into a plurality of array segments adapted to transmit a plurality of orthogonal radar waveforms to illuminate a target region extending in a range direction and in an azimuth direction; a waveform generator capable of generating the plurality (N) of orthogonal waveforms concurrently for radar illuminations whereas N is a positive integer; a receive antenna divided into a plurality of array segments, wherein the receive antenna is adapted to receive a radar return from the target region and to generate a plurality of return signals associated with corresponding ones of the plurality of array segments; a post processing performing three functions on Radar return signals;
(1) synthesizing receiving beams, (2) generating virtual transmit beams, and (3) performing conventional radar ranging and Doppler processing and advanced mobile target indication (MTI) processing. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38)
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Specification