Signal direction processing for an antenna array

Patent metadata

Field	Value
Publication number	US-2017102445-A1
Application number	US-201514882034-A
Country	US
Kind code	A1
Filing date	Oct 13, 2015
Priority date	Oct 13, 2015
Publication date	Apr 13, 2017
Grant date	—

Abstract

Systems and methods are provided for determining a direction of a signal received at an antenna array. An antenna array includes a plurality of antenna elements, including a reference element. A signal combiner element is configured to combine weighted signals from a subset of the plurality of antenna elements to provide a composite output. An adaptive processing component is configured to determine an optimal set of weights for the subset of the plurality of antenna elements. An angle of arrival search component is configured to find a direction of minimum gain given the optimal set of weights.

First claim

Having described the invention, the following is claimed:

1 . A system for determining a direction of a signal received at an antenna array comprising:
an antenna array, comprising a plurality of antenna elements, including a reference element; a signal combiner element configured to combine weighted signals from a subset of the plurality of antenna elements to provide a composite output; an adaptive processing component configured to determine an optimal set of weights for the subset of the plurality of antenna elements; and an angle of arrival search component configured to find a direction of minimum gain given the optimal set of weights.

2 . The system of claim 1 , the adaptive processing component being configured to determine the optimal set of weights as a set of weights that minimize a mean squared error between the composite output and an output of the reference element.

3 . The system of claim 2 , wherein the adaptive processing component is configured to calculate the optimal set of weights, w , as w=[E{ xx *}] −1 E{ x r*}, where x is a vector of signal values from the sunset of plurality of antenna elements, the superscript * denotes a complex conjugate of a term, and r is the output of the reference element.

4 . The system of claim 2 , wherein the adaptive processing component is configured to calculate the optimal set of weights, w , as, w =[ q q *] −1 { x r*} where x is a vector of signal values from the subset of plurality of antenna elements, the superscript * denotes a complex conjugate of a term, q =E{ x p*}, p is a locally generated replica of the signal, s, and r is the output of the reference element.

5 . The system of claim 2 , wherein the adaptive processing component is configured to calculate the optimal set of weights, w , as, w =[ q q *+C n ] −1 { x r*} where x is a vector of signal values from the subset of the plurality of antenna elements, the superscript * denotes a complex conjugate of a term, q =E{ x p*}, p is a locally generated replica of the signal, s, C n is an approximation of a covariance matrix of the thermal noise in the receiver, and r is the output of the reference element.

6 . The system of claim 1 , wherein the subset of the plurality of antenna elements is a proper subset of the plurality of antenna elements.

7 . The system of claim 1 , wherein the angle of arrival search component is configured to iteratively search across a range of possible angles, such that a first search is performed at a coarse quantization level to narrow the range of possible angles and a final search is performed at a fine quantization level to determine the angle of arrival.

8 . The system of claim 7 , wherein the first search is performed in increments of ten degrees, and the final search is performed in increments of one hundredth of a degree.

9 . A method for determining a direction of a signal received at an antenna array comprising:
receiving a signal at a plurality of antenna elements, including a reference element; applying weights to received signals at a subset of the plurality of antenna elements; combining the weighted signals from a subset of the plurality of antenna elements to provide a composite output; determining an optimal set of weights for the subset of the plurality of antenna elements as a set of weights that minimize a mean squared error between the composite output and an output of the reference element; and determining an angle of arrival for the signal from the determined optimal set of weights.

10 . The method of claim 9 , wherein determining the angle of arrival from the determined optimal set of weights comprises finding a direction of minimum gain given the optimal set of weights.

11 . The method of claim 10 , wherein finding the direction of minimum gain given the optimal set of weights comprises iteratively searching across a range of possible angles, the iterative search comprising:
performing a first search at a coarse quantization level to narrow the range of possible angles; and performing a final search at a fine quantization level to determine the angle of arrival.

12 . The method of claim 9 , wherein determining the optimal set of weights comprises calculating the optimal set of weights, w , as w=[E{ xx *}] −1 E{ x r*}, where x is a vector of signal values from the sunset of plurality of antenna elements, the superscript * denotes a complex conjugate of a term, and r is the output of the reference element.

13 . The method of claim 9 , wherein determining the optimal set of weights comprises calculating the optimal set of weights, w , as, w =[ q q *] −1 { x r*} where x is a vector of signal values from the subset of plurality of antenna elements, the superscript * denotes a complex conjugate of a term, q =E{ x p*}, p is a locally generated replica of the signal, s, and r is the output of the reference element.

14 . The method of claim 9 , wherein determining the optimal set of weights comprises calculating the optimal set of weights, w , as, w =[ q q *+C n ] −1 { x r*} where x is a vector of signal values from the subset of the plurality of antenna elements, the superscript * denotes a complex conjugate of a term, q =E{ x p*}, p is a locally generated replica of the signal, s, C n is an approximation of a covariance matrix of the thermal noise in the receiver, and r is the output of the reference element.

15 . The method of claim 9 , wherein the subset of the plurality of antenna elements is an improper subset of the plurality of antenna elements.

16 . A system for determining a direction of a signal received at an antenna array comprising:
an antenna array, comprising a plurality of antenna elements, including a reference element; a signal combiner element configured to combine weighted signals from a subset of the plurality of antenna elements to provide a composite output; an adaptive processing component configured to determine an optimal set of weights for the subset of the plurality of antenna elements as a set of weights that minimize a mean squared error between the composite output and an output of the reference element; and an angle of arrival search component configured to find a direction of minimum gain given the optimal set of weights.

17 . The system of claim 16 , wherein the adaptive processing component is configured to calculate the optimal set of weights, w , as w =[E{ xx *}] −1 E{ x r*}, where x is a vector of signal values from the sunset of plurality of antenna elements, the superscript * denotes a complex conjugate of a term, and r is the output of the reference element.

18 . The system of claim 16 , wherein the adaptive processing component is configured to calculate the optimal set of weights, w , as, w =[ q q *] −1 { x r*} where x is a vector of signal values from the subset of plurality of antenna elements, the superscript * denotes a complex conjugate of a term, q =E{ x p*}, p is a locally generated replica of the signal, s, and r is the output of the reference element.

19 . The system of claim 16 , wherein the adaptive processing component is configured to calculate the optimal set of weights, w , as, w =[ q q *+C n ] −1 { x r*} where x is a vector of signal values from the subset of the plurality of antenna elements, the superscript * denotes a complex conjugate of a term, q =E{ x p*}, p is a locally generated replica of the signal, s, C n is an approximation of a covariance matrix of the thermal noise in the receiver, and r is the output of the refere

Assignees

• Mesecher David K
• Northrop Grumman Systems Corp

Inventors

• Mesecher David K

Classifications

• H04B7/086

  using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming · CPC title

• G01S3/32 Primary

  derived from different combinations of signals from separate antennas, e.g. comparing sum with difference · CPC title

• H01Q3/2635

  the auxiliary unit being composed of a plurality of antennas · CPC title

• H04K3/224

  with countermeasures at transmission and/or reception of the jammed signal, e.g. stopping operation of transmitter or receiver, nulling or enhancing transmitted power in direction of or at frequency of jammer · CPC title

• H01Q3/2629

  Combination of a main antenna unit with an auxiliary antenna unit · CPC title