Fig. 7.

(a) The measured SNR of proposed beamformer varying the aperture size in the first beamforming (left) and the second beamforming. One beamformer aperture size was fixed to be maximum when the other aperture size was varied. (b) The ground truth SNR results using a delay-and-sum algorithm with dynamic focusing. (c) The focusing depth and aperture size parameters in Figs. 7(a)-7(b) were compressed into the metric of f-number. To compensate the SNR variance for the same f-number but different target depth, the SNR of f-number 1.04 was normalized to be 0 dB. The theoretical ground truth values were computed by fitting the ground truth data from Fig. 7(b) into Eq. (9).