Adapive sidelobe canceller system

• US 4,689,628 A
• Filed: 08/16/1974
• Issued: 08/25/1987
• Est. Priority Date: 08/16/1974
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Lewis, Bernard L.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US05/499,357
• Time in Patent Office: 4,757 Days
• Field of Search: 343/100 LE, 343/100 CL, 325/371, 342/384, 342/381
• US Class Current: 342/384
• 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 3/2635 the auxiliary unit being composed of a plurality of antennas

Abstract

An improved signal processing technique for developing a plurality of indndent samples, particularly for use in a canceller system receiving interference from a plurality of sources. Each of a plurality of signal channels sample the environment from a plurality of interference source and provide inputs to a configuration of adaptive canceller loops. The loops are connected to provide independent samples of the interference environment from each of the signal channels. In a canceller system, each of the independent loop outputs aree then used as an input to a canceller loop in the main channel to cancel interference in the receiving system. By using the independent samples, a receiving system can significantly increase interference cancellation and reduce the number of recirculations or iterations required.

Claims

1. A system for preprocessing signals of a multiple signal environment having desired and undesired signals comprising:

a plurality of independent channel means for receiving undesired signals from a multiple signal environment and providing a plurality of output signals;

first means coupled to said channel means for decorrelating each of said channel output signals from the others to produce a plurality of independent samples; and

second means coupled to at least one of said channel means for providing a sample of a signal component correlated on all of said channel means.

2. The system of claim 1 wherein said first means comprises a plurality of canceller loops with each loop of said plurality of loops coupled to receive a first input signal from one of said channel means and a second input signal from a different one of said channel means and provide a decorrelated output signal representing one of said independent samples.

3. The system of claim 2 wherein each loop is connected to receive the first input signal from a channel means different than the channel means supplying the first input signals of all other loops of said plurality of loops.

4. The system of claim 3 wherein each of said canceller loops comprises, a canceller means coupled to receive and correlate components of said first and second signal to produce a correlated output and subtractor means coupled to subtract said correlated output from said first signal to provide said one of said independent samples, each of said canceller means being coupled to the output of its subtractor means to receive the subtractor output signal as said first signal.

5. The system of claim 4 wherein each of said channel means comprises an antenna for providing an output signal from the multiple signal environment.

6. The system of claim 5 wherein each antenna is an omnidirectional antenna.

7. The system of claim 1 further including:

a main channel means for receiving desired and undesired signals from the multiple signal environment and providing a main channel signal; and

means coupled to said main channel means and to said first means and said second means for comparing the undesired signals in said main channel signal with each of said samples and providing cancelling signals which reduce the undesired signals in said main channel signal.

8. The system of claim 7 wherein said means for comparing comprises a plurality of canceller loops with a plurality of said loops coupled to said first means in such a manner that each of said loops has an input from said main channel signal and input from an independent sample and provides a main signal output reduced in undesired signals and one of said loops is coupled to said second means in such manner that it has an input from said main channel signal and input from said second means sample and provides a main signal output reduced in undesired signal.

9. The system of claim 8 wherein each loop is connected to receive an input sample different from the input samples of all other loops of said plurality of loops.

10. The system of claim 9 wherein each of said canceller loops comprises, canceller means coupled to compare the undesired signal in the main channel with its respective sample and provide one of said cancelling signals and a subtractor means coupled to receive the main channel signal and subtract the cancelling signal therefrom to form said main signal output.

11. The system of claim 10 wherein each of the canceller means of each canceller loop is connected to receive the output of its own subtractor means as the main channel signal to thereby form a plurality of independent canceller loops.

12. The system of claim 11 wherein a subtractor means of one of the canceller loops is connected to receive said main channel signal from said main channel means, and each of the remaining subtractor means are serially connected such that the output from the previous subtractor means forms the main channel signal input to the next succeeding subtractor means until all of said subtractor means have been utilized.

13. The system of claim 12 wherein said first means comprises a plurality of canceller loops with each loop coupled to receive a first input signal from one of said channel means and a second signal from a different one of said channel means and provide a decorrelated output signal representing one of said independent samples.

14. The system of claim 13 wherein each loop of said first means is connected to receive the first input signal from an independent channel means different than the independent channel means supplying the first input signals of all other loops of said first means.

15. The system of claim 14 wherein each of said canceller loops of said first means comprises, a canceller means coupled to receive and correlate components of said first and second signal to produce a correlated output and subtractor means coupled to subtract said correlated output from said first signal to provide said one of said independent samples, each of said canceller means of said first means being coupled to the output of its subtractor means to receive said subtractor means output as said first signal.

16. The system of claim 15 wherein each of said channel means comprises an antenna for providing the channel output signal.

17. The system of claim 16 wherein the main channel antenna is a directional antenna and said independent channel antennas are omnidirectional antennas.