Adaptive beamformer with beam mainlobe maintenance

• US 6,166,689 A
• Filed: 08/12/1970
• Issued: 12/26/2000
• Est. Priority Date: 08/12/1970
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Gostin, Judson J., Huhta, Kalevi Hoobert, Hammel, Gene P, Dickey, Frank R. Jr., Vural, Ayhan M.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US05/063,113
• Time in Patent Office: 11,094 Days
• Field of Search: 343/100 SA, 343/100 LE, 340/6 R, 342/371, 342/381, 342/368, 342/372, 342/379
• US Class Current: 342/381
• CPC Class Codes: G01S 2013/0245 Radar with phased array antenna
• CPC Class Codes: G01S 3/043 Receivers
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: G01S 3/8006 Multi-channel systems specially adapted for direction-finding, i.e. having a single aerial system capable of giving simultaneous indications of the directions of different signals
• CPC Class Codes: G01S 3/801 Details G01S3/82, G01S3/84, G01S3/86 take precedence
• CPC Class Codes: G01S 3/808 using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays

Abstract

An adaptive beamformer and signal processor for sonar and other signal receptor arrays, in which beamforming is accomplished by correlation feedback loops providing matched weighting across the array. To constrain the adaptive beamformer thus comprised against cancellation of useful signals from a particular angular region, which normally is the beam mainlobe or boresight region, one or more spatial notch filters are interposed within the correlation feedback loops for preventing signal suppression within such angular region.

Claims

1. In combination with an array of wave receptors, an adaptive array beamformer comprising primary beamformer means for phase and amplitude weighting the elemental signals of said array with nominal weights so as to form and direct a beam mainlobe to the angle of desired maximum response of the array, auxiliary beamformer means for deriving perturbation weights from said elemental signals and for phase and amplitude weighting said signals with said perturbation weights so as to form and direct a null to the angle of arrival of interference, and mainlobe maintenance means including spatial notch filter means for inhibiting the operation of said auxiliary beamformer means upon approximate coincidence of the angle of said null with that of desired maximum response of the array.

2. An array beamformer as defined in claim 1 including means for weighting each of said elemental signals with the difference between said nominal and perturbation weights for that signal and then combining the signals thus weighted to form said beam mainlobe and null.

3. An array beamformer as defined in claim 1 including means for applying said perturbation weights to said elemental signals to form a perturbation beam and for subtracting said perturbation beam from the beam formed and directed by said nominal weights to thus form said null.

4. An array beamformer as defined in claim 1 wherein said spatial notch filter means comprises a plurality of filters each providing a notch spatially adjacent to but not coincident with the others to thereby inhibit the operation of said auxiliary beamformer over a relatively broad angular region about the angle of desired maximum response of the array.

5. An array beamformer as defined in claim 1 wherein said beamformer means comprises a plurality of feedback correlation loops each having as inputs the beamformer output and one of said elemental signals and being operative to generate one of said perturbation weights and to produce an output signal weighted thereby.

6. An array beamformer as defined in claim 5 wherein said feedback correlation loops are closed through said spatial notch filter means and are disabled thereby against generation of perturbation weights such as would place said null at said angle of desired maximum response of the array.