Adaptive antenna array

• US 4,780,721 A
• Filed: 03/21/1986
• Issued: 10/25/1988
• Est. Priority Date: 07/23/1984
• Status: Expired due to Term

• Current Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Original Assignee: Commonwealth of Australia
• Inventors: Dobson, Robin
• Primary Examiner(s): Blum, Theodore M.
• Assistant Examiner(s): Hellner, Mark
• Application Number:
  US06/849,457
• Time in Patent Office: 949 Days
• Field of Search: 342/378, 342/379, 342/380, 342/383, 342/386
• US Class Current: 342/178
• 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 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H04B 1/126 having multiple inputs, e.g. auxiliary antenna for receiving interfering signal aerials in general H01Q

Abstract

A method and device for removing undesired jammer signals from desired signals which comprises forming a beam on the desired signal in an adaptive antenna array characterized by an orthogonalizer array (12) to receive digitized signals from the antennas, and pass signals to a beamforming array (14) and including a late jammer canceller array (16) and an intelligent controller (24) arranged to control weights (W) and select a row having the desired beamformed signal.

Claims

1. A method of removing undesired directional interference jammer signals from desired signals and maximizing a signal-to-noise ratio using an orthogonalizer array which includes processors to which digitized signals from a series of antennas are fed, comprising the sequential steps of:

(a) determining a time when the desired signal is not present,

(b) nulling the directional interference sources at said time the desired signal is not present, by adjusting weight values in said orthogonalizer array using an intelligent controller to which output signals of processors of said orthogonalizer array are applied, and using said weight value determined for each said processor of said orthogonalizer array,

(c) freezing said weight values in the array above a null row, at which the jammers have been removed,

(d) nulling said desired signal at a row below said null row,

(e) beamforming on said desired signal at said null row during the presence of said desired signal after nulling said directional interference jammers,

(f) freezing the weights in the beamformer and row below the null row, and

(g) nulling any late directional interference jammers appearing on said beamforming desired signal.

2. The method of claim 1 wherein said nulling is effected by said orthogonalizer array and comprising the further steps of passing the signals processed by that array to a beamforming array,

further processing said signals and passing them to a late jammer canceller,

characterised in that the signals received from nodes of said orthogonalizer array and said beamforming array and said late canceller array are passed to the said intelligent controller through channels in which arrays of said weight values are determined and passed via channels to said orthogonalizer array and said beamforming array and said late canceller array, and selecting the desired signal by coupling an output selector with said intelligent controller to select the desired signal.

3. The method of claim 1 comprising the further steps of further submitting the derived digitized signals from each antenna output in the array to a Gram-Schmidt orthogonalizer array to orthogonalize the output of a first antenna with the output of each antenna in the row, then orthogonalizing the outputs of the first row orthogonalizer with the outputs of the orthogonalizers of each row to have all outputs orthogonal to each other, passing the output of each row to the intelligent controller connected to receive the output signals from the orthogonalizer array and to adjust the weight value in the orthogonalizer array, said intelligent controller also receiving the outputs of each row of the beamformer array and a later jammer canceller connected to receive the processed signals from the said beamformer array, said intelligent controller being connected to adjust the weights in said beamformer array and late jammer canceller and the selector via channels to output the desired signal, whereby to permit selection of the row at which the nulling operation stops, the row at which the desired signal is beamformed on, and to determine the presence and the null further jammers.

4. The method of claim 2 characterised in that the said intelligent controller is arranged to monitor the nodes in each row in the orthogonalizer array and to compare the signal levels at each row to determine environmental characteristics and optionally re-configuring the said array to match the said environment.

5. The method of claim 2 characterised in that the said signals passed to the said intelligent controller from the nodes of the said orthogonalizer array and the said beamforming array and the said late jammer canceller are in-phase and quadrature signals.

6. The method of claim 2 characterised in that the said signals passed to the said intelligent controller from the nodes of the said orthogonalizer array and the said beamforming array and the said late jammer canceller are obtained by use of tapped delay lines.

7. A method as in claim 1 wherein said nulling any late jammer step comprises the further steps of:

nulling said desired signal;

determining the presence of any late directional interference jammer in a channel where said and desired signal has been nulled; and

nulling said late directional interference jammers.

8. A method as in claim 1 comprising the further step of delaying said beamforming on said desired signal step by an amount of time to allow said adjusting weight values step to be completed.

9. A device for removing undesired jammer signals in an adaptive antenna array system, comprising:

initial interference cancelling means for receiving a desired signal from the adaptive antenna array, including an orthogonalizer array coupled to receive digitized signals from said antenna array, for determining an initial interference during an initial time when said desired signal is not present and for cancelling said initial interference;

a beamforming array coupled to said initial interference cancelling means, for receiving said desired signal with said interference cancelled and beamforming said signal;

a late jammer canceller array;

each said array comprising rows of orthogonal processors within rows of each array coupled to the rows of an adjacent array;

an intelligent controller coupled to receive signals from each processor of each said array; and

a selector under control of the intelligent controller, arranged to select a row having the desired beamformed signal.

10. An apparatus as in claim 9 wherein said beamforming array includes means for beamforming a signal by adding a weight that is in-phase with said signal and means for nulling said signal by adding a weight which is out-of-phase with said signal, wherein said intelligent controller includes means for processing said nulled signal to determine the presence of any late jammers, and means for commanding said late jammer canceller array to cancel out said late jammers so detected.

11. An apparatus as in claim 10 further comprising means for delaying said beamforming array from beamforming said signal by an amount of time sufficient to calculate respective weights for the respective signals.

12. An apparatus as in claim 9 wherein said initial interference cancelling means includes means for determining weights to cancel out said initial interference and means for freezing said weights after said initial time.

13. An apparatus as in claim 12 further comprising means for delaying said beamforming array from beamforming said signal by an amount of time sufficient to calculate respective weights for the respective signals.

14. An apparatus for removing undesired jammer signals from desired signals and to maximize the signal-to-noise ratio by forming a beam on a desired signal in adaptive antenna arrays in which rows of orthogonal processors receive digitized signals from each antenna in the array, comprising:

(a) an orthogonalizer array comprising rows of orthogonal processors for cancelling directional interference signals at a first time when the desired signal is not present,

(b) a beamforming array comprising rows of processors arranged to receive antenna signals and to receive the outputs of the rows of orthogonal processors and to beamform on the desired signal which has had said directional interference signals cancelled by said orthogonalizer array,

(c) a late jammer canceller array having rows of processors for receiving beamformed signals from said beamforming array and for cancelling jammer signals that were not present at said first time during the cancelling in said orthogonalizer array,

(d) intelligent controller means for receiving the signals from nodes of each of said processors of all of the arrays and for determining weight values for each processor of said arrays and applying the weight values to said processors in said arrays, and

(e) an output selector coupled to receive signals from said late jammer canceller array, and for selecting the desired beamformed signal under control of said intelligent controller.

15. The apparatus of claim 14 wherein there are a plurality of antennas, and further comprising:

means for submitting the digitized signals from each antenna in the array to said orthogonalizer array to orthogonalize the output of a first antenna with the output of each other antenna in the row, and

circuit means for orthogonalizing the outputs of first row orthogonalizers with the outputs of the orthogonalizers of each row to render all outputs orthogonal to each other, and for passing the output of each row to the intelligent controller means to receive the output signals from the orthogonalizer array and to adjust the weights in the orthogonalizer array.

16. The apparatus of claim 15 wherein said circuit means is also for transmitting the outputs of each row of said orthogonalizer array to said beamforming array and of said late jammer canceller to said intelligent controller means, said intelligent controller means being connected to adjust the weights in said orthogonalizer array and said beamforming array, and to late jammer canceller and selector to output the desired beamformed signal, whereby to permit selection of the row at which the nulling operation stops, the row at which the desired signal is beamformed on, and to determine the presence and to null further interference, said orthogonalizer array having the outputs of the rows coupled to the corresponding rows of said beamformer array and said beamformer array having the outputs of the rows coupled to the corresponding rows of said further jammer array whereby the nulling is first effected, then the beamforming, and then the nulling of further jammer signals.

17. An apparatus as in claim 14 further comprising means for delaying said beamforming array from beamforming said desired signal for amount of time necessary for said intelligent controller means to determine said weight values and to apply said weight values to said processors in said array.

18. An apparatus as in claim 14 further comprising means for freezing those of said weight values which cancel said directional interference signals at said first time.