Robustness of null broadening against source motion
H. C. Song, W. A. Kuperman, William S. Hodgkiss, Peter Gerstoft, J.S. Kim · 2003
Adaptive array beamforming achieves high resolution and sidelobe suppression by producing sharp nulls in the adaptive beampattern when using sample matrix inversion (SMI). In the presence of source motion, the adaptive processor often cannot provide sufficient nulling of the interferer, given the number of snapshots available, and this results in a masking of the desired target signal. The null broadening approach, originally developed to improve the robustness of adaptive beamforming for a stationary problem, is extended to the snapshot-deficient problem arising from the nonstationarity of the background interference. Null broadening allows strong interferers to move through resolution cells and increases the number of degrees of freedom, thereby improving the detection of weak stationary signals. Numerical simulations demonstrate the robustness of the null broadening approach.