Wideband capon beamforming with pre-steering

Passive beamforming in ultrasound therapy monitoring strives to estimate the energy emanating from a near-field source location by “steering” the wideband sensor signals with time delays, summing the steered signals, and computing the energy over a time interval. An image of the spatial energy distribution is obtained by repeating the process over a grid of imaging locations. Capon beamforming provides adaptive interference reduction through real-valued beamforming weights that are determined from the spatial covariance matrix of pre-steered wideband signals. We analyze the interference rejection of this Capon beamformer with pre-steered wideband signals and explain its effectiveness in ultrasound therapy monitoring.