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| Artificial Interference Power Estimation for Beamforming under Sidelobe Soft Constraint |
| Zeng Cao; Zhou Zheng-guang; Liao Gui-sheng |
| National Lab of Radar Signal Processing, Xidian University, Xi’an 710071,China |
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Abstract Often in practice the directional knowledge of signal of interest or interferences is imprecise, the adaptive beamformer with linear constraint is hypersensitive to the array imperfection which leads to the output Signal-to-Interference-plus-Noise Ratio (SINR) decreases when the input Signal-to-Noise Ratio (SNR) exceeds a certain threshold. In order to improve the robustness of the beamformer, a new method for estimating the artificial interference power under sidelobe soft constraint is proposed. Based on the prior coarse knowledge of Direction of Arrival (DOA) of the interferences and using the subspace projection and the null area extension techniques, the artificial interference power can be obtained through the iterative procedure under the soft constraint of the maximum peak undulation in sidelobe area. The method is not sensitive to the look direction mismatch and the sensors gain error with low sidelobe level and deep null. Numerical examples demonstrate its effectiveness and robustness comparing with other methods.
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Received: 29 May 2006
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2007, Vol. 29 
