Patent ID: 7280627

Claim:
A method of suppressing side lobe interference in a beamforming process, the method comprising: receiving a plurality of sensor signals comprising elemental data; forming a main beam comprised of main beam samples using all of the sensor signals, wherein said forming includes applying weights to the main beam samples to reduce sidelobe levels of the main beam; combining a small subset of the plurality of sensor signals into signal pairs, wherein the small subset of the plurality of sensor signals that are combined into the signal pairs comprise signals from sensors that are adjacently located near the edges of the array; calculating a complex weighting factor for each signal in a pair of the signal pairs such that the maximum response axis of the resulting signal pair combination is aligned with the maximum response axis of the main beam; assigning opposite amplitudes to each signal in the pair to produce delta-channel auxiliary signals having zero response along the maximum response axis; computing a covariance matrix, M, using the delta-channel auxiliary signals, wherein each member of the covariance matrix, M, is an estimate of the covariance between two delta-channel auxiliary signals such that the whole matrix contains estimates of every possible delta-channel auxiliary signal combination and the main diagonal of the covariance matrix contains the variance of the corresponding delta-channel auxiliary signal; computing a cross-covariance vector, Λ, using the delta-channel auxiliary signals and the main beam; computing a vector of delta-channel auxiliary signal weights; multiplying each sample from each delta-channel auxiliary signal by its corresponding weight to yield weighted delta-channel auxiliary signals; summing the weighted delta-channel auxiliary signals to obtain suppressor channel samples; and subtracting the suppressor channel samples from the main beam samples to obtain an interference-free main beam.