Short-range point defense radar

Patent metadata

Field	Value
Publication number	US-9810774-B2
Application number	US-201414540116-A
Country	US
Kind code	B2
Filing date	Nov 13, 2014
Priority date	Nov 13, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A multi-beam frequency-modulated continuous wave (FMCW) radar system designed for short range (<20 km) operation in a high-density threat environment against highly maneuverable threats. The multi-beam FMCW system is capable of providing continuous updates, both search and track, for an entire hemisphere against short-range targets. The multi-beam aspect is used to cover the entire field of regard, whereas the FMCW aspect is used to achieve resolution at a significantly reduced computational effort.

First claim

The invention claimed is:

1. A method for simultaneous detection of multiple short-range targets using radar, comprising:
(a) illuminating a wide field of regard with frequency-modulated continuous wave radar signals comprising a sequence of linear frequency-modulated sweeps using a transmit antenna;
(b) for each linear frequency-modulated sweep of said sequence, receiving radar signals reflected from the field of regard within a short range using a receive antenna array having a multiplicity of antenna elements;
(c) converting the reflected radar signals into a respective multiplicity of pencil beams for each linear frequency-modulated sweep of said sequence using two-dimensional beamforming; and
(d) for each linear frequency-modulated sweep of said sequence, detecting any pencil beams of said multiplicity of pencil beams having a characteristic indicative that radar signals were reflected from a target in the field of regard,
wherein said two-dimensional beamforming and said target detection are performed by a computer system.

2. The method as recited in claim 1 , wherein step (c) comprises:
converting the received radar signals into respective digital in-phase and quadrature samples for each antenna element;
forming a respective multiplicity of simultaneous azimuth beams from said digital in-phase and quadrature samples for each linear frequency-modulated sweep of said sequence, said azimuth beams of each multiplicity being aimed at respective azimuth angles; and
forming the respective multiplicity of pencil beams from said azimuth beams for each linear frequency-modulated sweep of said sequence using elevation beamforming.

3. The method as recited in claim 1 , wherein step (d) comprises:
forming a multiplicity of range bins for each pencil beam;
Doppler processing said range bins across multiple linear frequency-modulated sweeps; and
computing a range of the target based on results of said Doppler processing.

4. The method as recited in claim 1 , further comprising starting a track on the target when an M of N target detection threshold is reached, where M and N are positive integers and M<N.

5. The method as recited in claim 4 , further comprising continuously updating the track on the target.

6. The method as recited in claim 5 , wherein the track is continuously updated every coherent integration time.

7. The method as recited in claim 1 , further comprising computing azimuth and elevation angles of the target using angle discrimination.

8. The method as recited in claim 1 , wherein the transmit antenna and the receive antenna array are at different locations.

9. A radar system capable of simultaneous detection of multiple short-range targets, comprising:
an exciter capable of generating frequency-modulated continuous wave radio frequency signals comprising a sequence of linear frequency-modulated sweeps;
a receiver comprising a multiplicity of mixers for mixing radio frequency signals with replicas of said frequency-modulated continuous wave radio frequency signals and outputting analog signals;
one or more antennas for converting frequency-modulated continuous wave radio frequency signals generated by said exciter into electromagnetic waves and converting returned electromagnetic waves into radio frequency signals which are sent to said receiver;
means for converting analog signals from said receiver into digital samples;
a digital azimuth beamformer that forms a multiplicity of narrow azimuth beams from digital samples produced for each linear frequency-modulated sweep;
a digital elevation beamformer that forms a multiplicity of pencil beams from the multiplicity of narrow azimuth beams produced for each linear frequency-modulated sweep; and
a digital signal processor programmed to detect any pencil beams of said multiplicity of pencil beams having a characteristic indicative that radar signals were reflected from a target in the field of regard for each linear frequency-modulated sweep.

10. The radar system as recited in claim 9 , wherein said digital signal processor is programmed to perform the following operations:
forming a multiplicity of range bins for each pencil beam;
Doppler processing said range bins across multiple linear frequency-modulated sweeps; and
computing a range of the target based on results of said Doppler processing.

11. The radar system as recited in claim 9 , further comprising a track processor programmed to start a track on the target when an M of N target detection threshold is reached, where M and N are positive integers and M<N.

12. The radar system as recited in claim 11 , wherein said track processor is further programmed to continuously update the track on the target.

13. A method for simultaneous detection of multiple short-range targets using radar, comprising:
(a) illuminating a wide field of regard with frequency-modulated continuous wave radar signals comprising a sequence of linear frequency-modulated sweeps using a transmit antenna;
(b) for each linear frequency-modulated sweep of said sequence, receiving radar signals reflected from the field of regard within a short range using a receive antenna array having a multiplicity of antenna elements;
(c) converting the reflected radar signals into a respective multiplicity of fan beams for each linear frequency-modulated sweep of said sequence using two-dimensional beamforming;
(d) for each linear frequency-modulated sweep of said sequence, detecting any fan beams of said multiplicity of fan beams having a characteristic indicative that radar signals were reflected from a target in the field of regard; and
(e) forming a multiplicity of pencil beams for any fan beam for which a target was detected,
wherein said two-dimensional beamforming and steps (d) and (e) are performed by a computer system.

14. The method as recited in claim 13 , wherein step (d) comprises:
forming a multiplicity of range bins for each pencil beam;
Doppler processing said range bins across multiple linear frequency-modulated sweeps; and
computing a range of the target based on results of said Doppler processing.

15. The method as recited in claim 13 , further comprising starting a track on the target when an M of N target detection threshold is reached, where M and N are positive integers and M<N.

16. The method as recited in claim 15 , further comprising continuously updating the track on the target.

17. The method as recited in claim 16 , wherein the track is continuously updated every coherent integration time.

18. The method as recited in claim 13 , further comprising computing azimuth and elevation angles of the target using angle discrimination for any pencil beams of said multiplicity of pencil beams having a characteristic indicative that radar signals were reflected from a target in the field of regard.

19. A radar system capable of simultaneous detection of multiple short-range targets, comprising:
an exciter capable of generating frequency-modulated continuous wave radio frequency signals comprising a sequence of linear frequency-modulated sweeps;
a receiver comprising a multiplicity of mixers for mixing radio frequency signals with replicas of said frequency-modulated continuous wave radio frequency signals and outputting analog signals;
one or more antennas for converting frequency-modulated continuous wave radio frequency signals generated by said exciter into electromagnetic waves and converting returned electromagnetic waves into radio frequency signals which are sent to said receiver;
means for converting analog

Assignees

• Boeing Co

Inventors

• Wittenberg Peter S

Classifications

• G01S2013/0263

  Passive array antenna · CPC title

• G01S13/343

  using sawtooth modulation · CPC title

• G01S2007/356

  Physics · mapped topic

• G01S13/003

  Bistatic radar systems; Multistatic radar systems · CPC title

• G01S13/4463

  using phased arrays · CPC title