Array adaptive beamforming for a large, arbitrary, sparse array

Patent metadata

Field	Value
Publication number	US-9819083-B1
Application number	US-201414468509-A
Country	US
Kind code	B1
Filing date	Aug 26, 2014
Priority date	Aug 26, 2014
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

A method and apparatus in one example uses adaptive digital beamforming with a plurality of heterogeneous antennas which are more affordable and flexible and do not require the use of a nuller antenna. The method uses adaptive, multi-beam digital beamforming without knowledge of a signal direction or aperture of the antena. The method works with arbitrary antenna elements in arbitrary locations and does not require any a priori antenna model. The method also optimizes signal-to-noise ratio (SNR) of the received signal.

First claim

What is claimed is:

1. A method for adaptive digital beamforming, in a computer processor, the input signals received by a plurality of heterogeneous antennas, comprising the steps of:
receiving an input signal from each beam of the plurality of antennas;
estimating an initial weight for each beam only from information contained within the input signals without using a model of the plurality of heterogeneous antennas or knowing the location of a desired signal;
processing the input signals to iteratively estimating a new weight for each beam until an optimum weight is achieved; and
processing the input signals by applying the optimum weight for each beam to the input signals to digitally beamform the desired signal.

2. The method of claim 1 where in the step of estimating an initial weight further comprises the steps of:
estimating an initial steering vector from the input signals from the one or more antennas;
estimating an initial covariance matrix from the input signals using dynamic noise loading; and
generating a set of weights for the input signals from the one or more antennas from the initial steering vector and the initial covariance matrix.

3. The method of claim 1 wherein the step of estimating an initial weight per beam further comprises the step of calculating a dynamic noise loading according to the equation

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where R XX is a covariance matrix of received symbols from antenna beams, R xx _ diag _ sort =sort(diag(R XX ), descend), c nl is a constant, and N beam =the number of heterogeneous antennas.

4. The method of claim 2 wherein R xx _ diag _ sort contains the diagonal elements of R XX in descending order, and N beam ≧3.

5. The method of claim 1 , wherein the plurality of heterogeneous antennas further comprises an arbitrary beamforming network of arbitrary antenna elements.

6. The method of claim 5 , wherein the arbitrary antenna elements are in arbitrary locations in a satellite.

7. The method of claim 5 , wherein the arbitrary antenna elements are in arbitrary locations in an airborne network.

8. The method of claim 5 , wherein the arbitrary antenna elements are in arbitrary locations in an ground network.

9. The method of claim 5 , wherein the arbitrary antenna elements are in arbitrary locations in any space, airborne, and ground network, and any combinations of networks.

10. The method of claim 1 , wherein a set of waveforms from the plurality of antennas is either coherent or partially coherent.

11. A method for digital beamforming the beams from a plurality of heterogeneous antennas, said method executed in a computer processor, comprising the steps of:
receiving an input signal from each beam of the plurality of antennas;
processing each input signal statistically to generate symbols representing each input signal;
estimating an initial steering vector for each beam from the input signal and the generated symbols;
estimating an initial covariance matrix using direct calculation with dynamic noise loading;
generating a set of weights for the beams from the plurality of antennas from the initial steering vector and the initial covariance matrix;
iteratively estimating a new weight for each beam until an optimum weight is achieved; and
normalizing the optimum weight and applying it to the received symbols during digital beamforming.

12. The method of claim 11 , further comprising the step of phase rotation to resolve sign ambiguity of the beamformed symbols.

13. The method of claim 11 , wherein the plurality of heterogeneous antennas further comprises an arbitrary beamforming network of arbitrary antenna elements.

14. The method of claim 13 , wherein the arbitrary antenna elements are in arbitra

Assignees

• Northrop Grumman Systems Corp

Inventors

• Chen Yenming
• Trippett John M
• Siegrist Scott

Classifications

• H01Q3/40 Primary

  with phasing matrix · CPC title

• H01Q1/288

  Satellite antennas · CPC title

• H01Q25/007

  using two or more primary active elements in the focal region of a focusing device (for operation on different wavebands H01Q5/22) · CPC title