Beamforming/null-steering adaptive array

• US 4,771,289 A
• Filed: 02/20/1987
• Issued: 09/13/1988
• Est. Priority Date: 05/28/1982
• Status: Expired due to Term

• Current Assignee: Hazeltine Corporation (BAE Systems Plc)
• Original Assignee: Hazeltine Corporation (BAE Systems Plc)
• Inventors: Masak, Raymond J.
• Primary Examiner(s): Blum, Theodore M.
• Assistant Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US07/017,109
• Time in Patent Office: 571 Days
• Field of Search: 342/368, 342/378-384
• US Class Current: 342/383
• CPC Class Codes: H01Q 3/2617 Array of identical elements

Abstract

A beamforming adaptive control loop is simultaneously employed in combination with a null-steering adaptive control loop to enhance the signal/interference ratio resulting in an increase in the messasge quality. The loops may employ temporal processing in which case on-epoch sample/hold filters and off-epoch sample/hold filters form separate loops which enhance the desired signal and cancel the undesired signal, respectively. The correlated output from the beamforming loop is added to the correlated output of the null-steering loop and mixed with the incoming signal.

Claims

1. An apparatus for cancelling undesired signals received with a desired spread spectrum signal, said apparatus comprising:

first means for providing the desired and any undesired signals received with the desired signal;

null-steering means, including a first temporal processing means associated with said first means, for temporally separating the desired and any undesired signals and cancelling at least a portion of any undesired signals;

beamforming means, including a second temporal processing means associated with said first means, for temporally separating the desired and any undesired signals and enhancing at least a portion of the desired signal; and

second means for coordinating said null-steering means and said beamforming means;

wherein said first temporal processing means comprises a first adaptive control loop coupled to said first means, said first loop having a negative correcting output for minimizing the undesired signal;

said second temporal processing means comprises a second adaptive control loop coupled to said first means, said second loop having a positive correcting output for maximizing the desired signal; and

said second means comprises means for summing the negative correcting output and the positive correcting output, and a mixer for mixing the desired and any undesired signals with the sum to provide a mixed output;

further wherein said first adaptive control loop comprises a first off-epoch sample-and-hold filter circuit coupled to the first means and providing an off-epoch unmixed output, a second off-epoch sample-and-hold filter circuit coupled to the mixed output and providing an off-epoch mixed output, and a correlator for correlating the off-epoch unmixed output with the off-epoch mixed output to provide said negative correcting output;

and finally wherein each of said epoch filter circuits includes means for tracking a desired signal, said tracking means including an early-gate and a late-gate overlapping a time of occurrence of the desired signal, there being an off-epoch gate and an on-epoch gate driven by said tracking means, for extracting samples of the desired signal and any interfering signal.

2. The apparatus of claim 1 wherein said second adaptive control loop comprises a first on-epoch sample-and-hold filter circuit coupled to the first means and providing an on-epoch unmixed output, a second on-epoch sample-and-hold filter circuit coupled to the mixed output and providing an on-epoch mixed output, and a correlator for correlating the on-epoch unmixed output with the on-epoch mixed output to provide said positive correcting output;

and wherein each of said on-epoch filter circuits includes means for tracking a desired signal, said tracking means including an early-gate and a late-gate overlapping a time of occurrence of the desired signal, there being an off-epoch gate and an on-epoch gate driven by said tracking means, for extracting samples of the desired signal and any interfering signal.