Multiresolution Quadtree Beamformer

The delay-sum beamformer (DSBF) is a space-time domain beamforming,method that performs coherent summation of sensor data. However, the computational complexity of finding the steered response over all angles is O(N³). In this paper, an O(N²log2 N) space-time domain beamforming algorithm it is proposed. This fast algorithm does not require uniform sensor spacing. It is called Quadtree Beamformer (QBF) because it is based on the iterative subband spectral decomposition method that has been used in the Quadtree BackProjection SAR imaging algorithm. The QBF is implemented by recursively performing a spectral decomposition process over the space-time domain sensor array data. It also provides intermediate stage data that can be used for multi-angle multiresolution beamforming.