Claims
- 1. A beamforming system adapted for use with an array antenna having a plurality of antenna elements, said beamforming system comprising:
first means for transforming a signal received by said antenna into a plurality of frequency subbands; second means for performing adaptive array processing on each of said subbands and providing a plurality of adaptively processed subbands in response thereto; and third means for normalizing said adaptively processed subbands.
- 2. The invention of claim 1 wherein said first means includes means for performing a Fast Fourier Transform on said received signal.
- 3. The invention of claim 2 wherein said first means includes a radio frequency receiver.
- 4. The invention of claim 3 wherein said first means includes an analog-to-digital converter coupled to the output of said radio frequency receiver and adapted to provide a plurality of samples in response to receipt of said signal.
- 5. The invention of claim 4 wherein said first means includes means for forming blocks of said samples.
- 6. The invention of claim 5 wherein said first means further includes means for amplitude weighting said sample blocks to provide a windowing function with respect thereto.
- 7. The invention of claim 6 wherein said first means further includes a bandpass filter adapted to filter the output of said means for performing a Fast Fourier Transform on said received signal.
- 8. The invention of claim 2 further including means for performing an inverse Fast Fourier Transform on said received signal.
- 9. The invention of claim 1 wherein said second means includes an adaptive array processor for each frequency subband.
- 10. The invention of claim 9 wherein each of said adaptive array processors includes means for applying a weight to a respective frequency subband for each of said elements of said array.
- 11. The invention of claim 10 wherein said weights are chosen to steer a beam in a direction of a desired signal.
- 12. The invention of claim 11 wherein each of said adaptive array processors further includes means for combining the outputs of said means for applying a weight to a respective frequency subband for each of said elements of said array to provide a single output signal for each subband.
- 13. The invention of claim 12 wherein said third means includes means for adjusting the amplitude of one or more of said subbands.
- 14. A beamforming system adapted for use with a GPS receiver and an array antenna having a plurality of antenna elements, said beamforming system comprising:
an FFT transforming a signal received by said antenna into a plurality of frequency subbands; an adaptive array processor arrangement for processing on each of said subbands and providing a plurality of adaptively processed subbands in response thereto, said arrangement including an adaptive array processor for each frequency subband, each of said adaptive array processors including means for applying a weight to a respective frequency subband for each of said elements of said array, said weights being chosen to steer a beam in a direction of a desired signal; and a processor for adjusting the amplitude of one or more of said subbands.
- 15. The invention of claim 14 wherein each of said adaptive array processors further includes means for combining the outputs of said means for applying a weight to a respective frequency subband for each of said elements of said array to provide a single output signal for each subband.
- 16. The invention of claim 14 wherein said first means includes means for performing a Fast Fourier Transform on said received signal.
- 17. The invention of claim 16 wherein said first means includes a radio frequency receiver.
- 18. The invention of claim 17 wherein said first means includes an analog-to-digital converter coupled to the output of said radio frequency receiver and adapted to provide a plurality of samples in response to receipt of said signal.
- 19. The invention of claim 18 wherein said first means includes means for forming blocks of said samples.
- 20. The invention of claim 19 wherein said first means further includes means for amplitude weighting said sample blocks to provide a windowing function with respect thereto.
- 21. The invention of claim 20 The invention of Claim wherein said first means further includes a bandpass filter adapted to filter the output of said means for means for performing a Fast Fourier Transform on said received signal.
- 22. The invention of claim 16 further including means for performing an inverse Fast Fourier Transform on said received signal.
- 23. A beamforming method adapted for use with an array antenna having a plurality of antenna elements, said beamforming method including the steps of:
transforming a signal received by said antenna into a plurality of frequency subbands; performing adaptive array processing on each of said subbands and providing a plurality of adaptively processed subbands in response thereto; and normalizing said adaptively processed subbands.
- 24. The invention of claim 23 wherein said signal is a GPS signal.
- 25. The invention of claim 23 wherein said step of performing adaptive array processing further includes the step of applying a weight to a respective frequency subband for each of said elements of said array.
- 26. The invention of claim 25 further including the step of choosing said weights to steer a beam in a direction of a desired signal.
- 27. The invention of claim 26 further including the step of combining the outputs of said step of applying a weight to a respective frequency subband for each of said elements of said array to provide a single output signal for each subband.
- 28. The invention of claim 23 wherein said step of normalizing further includes the step of adjusting the amplitude of one or more of said subbands.
Government Interests
[0001] This invention was made with Government support under Contract No. F08630-96-C-0018 awarded by the Department of the Air Force. The Government has certain rights in this invention.