Image reconstruction from coded excitation transmit schemes using a linear model approach

Coded excitation for array imaging increases SNR over uncoded bursts. Though matched filtering is optimal for isolated targets, a linear statistical model (LSM) generalizes to distributed targets, and can balance image bias against precision. We illustrate an LSM scheme that first estimates the medium impulse response, then computes retrospective transmission and imaging. We compare conventional compact-burst pulse-echo acquisition against a hybrid transmission scheme employing phase shift keying (BPSK) and pulse-position modulation (PPM) with multiple pulses in-flight. We demonstrate Doppler imagery using ultrasound data captured on a research ultrasound system employing a nonlinear class-D pulser.