Radar system and method of digital beamforming

• US 20090085800A1
• Filed: 02/28/2008
• Published: 04/02/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Searcy, James F., Alland, Stephen W.
• Granted Patent: US 7,639,171 B2
• Time in Patent Office: Days
• US Class Current: 342/25.R
• CPC Class Codes: G01S 13/26 wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/524 based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi
• CPC Class Codes: G01S 13/582 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 7/034 Duplexers switching devices for waveguides H01P1/10; transmit-receive switching in transceivers H04B1/44
• CPC Class Codes: G01S 7/2883 using FFT processing
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0842 Weighted combining

Abstract

A radar system and method is provided, in which the radar system includes a first transmitting portion of antenna elements, a second transmitting portion of antenna elements, and a receiving portion of antenna elements, such that the receiving antenna elements form a plurality of subarrays that represent real and synthetic antenna elements. The radar system further includes a transceiving device having a switching matrix. At least first and second switching transmit antenna elements are configured and time-multiplexed, wherein a receive aperture of the receiving antenna elements is increased. A first signal transmitted is received by the real antenna elements and a second signal transmitted is received by the real antenna elements, and combined so that the signals received from the first switching transmit antenna element represents a signal received by the real receive antenna element, and the signal received from the second switching transmit antenna element represents a signal received by the synthetic receive antenna element.

Claims

1. A radar system comprising:

a plurality of antenna elements comprising;

a first transmit antenna element;

a second transmit antenna element; and

a receiving portion of antenna elements, such that said receiving antenna elements form a plurality of subarrays that represent real and synthetic receive antenna elements;

a transceiving device comprising a switching matrix, wherein said transceiving device is in communication with said transmitting portion of antenna elements and said receiving portion of antenna elements that receives at least a portion of said plurality of signals transmitted by said transmitting portion of antenna elements, and said switching matrix time-multiplexes said transmitting and receiving portion of antenna elements; and

at least said first and second switching transmit antenna elements configured and time-multiplexed with respect to said receiving portion of said antenna elements, such that a first signal transmitted by said first switching transmit antenna element is received by at least one said real antenna element and a second signal transmitted by said second switching transmit antenna element is received by at least one said real antenna element, and wherein said received signals are combined so that said signal received from said first switching transmit antenna element represents a signal received by said real receive antenna element and said signal received from said second switching transmit antenna element represents a signal received by said synthetic receive antenna element, wherein a receive aperture of said receiving portion of antenna elements is increased.

2. The radar system of claim 1 further comprising a processor in communication with said transceiving device, wherein said processor beam forms and scans said signals received by said receiving portion of antenna elements.

3. The radar system of claim 1, wherein said increased receive aperture forms a narrow beamwidth of said signal transmitted by said transmitting portion of antenna elements.

4. The radar system of claim 1, wherein said synthetic antenna elements are displaced from said real antenna elements with respect to a predetermined distance between said signals transmitted by said first and second switched transmit antenna elements.

5. The radar system of claim 1, wherein digital beamforming of said signal transmitted from said transmitting portion of antenna elements using data from said signals received by said real receive elements and said signals received by said synthetic receive elements, produces a receive antenna gain and beamwidth corresponding to said real receive elements in addition to said synthetic receive elements.

6. The radar system of claim 1, wherein said transmitted signals are a simultaneous transmit and receive pulse Doppler (STAR-PD) frequency modulated waveform.

7. The radar system of claim 6, wherein a first interleaved STAR-PD signal is transmitted by said first switching transmit antenna element and a substantially identical interleaved STAR-PD signal is transmitted by said second switching transmit antenna element.

8. The radar system of claim 6, wherein said STAR-PD signal comprises substantially identical linear frequency modulated chirps, and a processor processes said STAR-PD signal, such that each of at least a portion of said chirps is transformed into range bins for each chirp and at least a portion of said range bins are transformed into Doppler bins.

9. The radar system of claim 8, wherein said processor non-coherently integrates said range-Doppler bins and performs detection substantially prior to digital beamforming, such that transformation into angle bins is substantially limited to said range-Doppler bins with detections.

10. The radar system of claim 1, wherein a processor oversamples time-multiplexed baseband data by a predetermined factor for range cutoff of said received signals.

11. The radar system of claim 10, wherein said oversampled time-multiplexed baseband data is combined with multi-dwell unfolding, for range cutoff of said received signals and range-Doppler unfolding.

12. The radar system of claim 1, wherein said transceiving device down-converts and samples said time-interleaved data within a signal received from each said antenna element of said receiving portion of antenna elements.

13. The radar system of claim 1, wherein a processor beam forms and scans said signal by combining sampled data of said signal from each said antenna element of said receiving portion of antenna elements with amplitude and phase weighting.

14. A method of electronically scanning a radar signal, said method comprising the steps of:

transmitting a plurality of signals by a plurality of switching transmit antenna elements, such that a first switching transmit antenna element of said plurality of switching transmit antenna elements transmits a first signal;

switching between said plurality of switching transmit antenna elements, such that a second switching transmit antenna element of said plurality of switching transmit antenna elements transmits a second signal;

receiving at least a portion of said transmitted plurality of signals by a transceiving device comprising a plurality of receiving antenna elements;

time-multiplexing said received signals, such that said first transmitted signal is received by at least one real antenna element of said plurality of receiving antenna elements and said second transmitted signal is received by at least one real antenna element of said plurality of receiving antenna elements, and combining said received signals, such that the signal received from said first switching transmit antenna element represents a signal received by said real receive antenna element, and the signal received from said second switching transmit antenna element represents a signal received by said synthetic receive antenna element, wherein a receiving aperture of said plurality of receiving antenna elements is increased.

15. The method of claim 14, wherein said increased receive aperture forms a narrow beamwidth of said signal transmitted by said transmitting portion of antenna elements.

16. The method of claim 14, wherein synthetic receive elements are displaced from real receive elements with respect to a predetermined distance between said signals transmitted by said first and second switching transmit antenna elements.

17. The method of claim 14, wherein said step of forming a beam comprises digitally beamforming said signals received by said real receive elements and said signals received by said synthetic receive elements, to produce a receive antenna gain corresponding to said real receive elements in addition to said synthetic receive elements.

18. The method of claim 14, wherein said transmitted signals are a simultaneous transmit and receive pulse Doppler (STAR-PD) frequency modulated waveform.

19. The method of claim 14 further comprising the step of oversampling said time-multiplexed baseband data by a predetermined factor.

20. The method of claim 14 further comprising the step of down-converting and sampling said time-interleaved data within signal received from each said receiving antenna element, and beamforming and scanning said signal by combining sampled data of said signal from each said receiving antenna element with amplitude and phase weighting.