Performance Enhancement of Coded Excitation in Ultrasonic B-mode Images

This paper presents a new coded excitation/pulse compression scheme that efficiently increase the signal to noise ratio, spatial resolution and image contrast using a modified matched filter. The proposed method implements a simple form of spatial filtering and uses a filter bank of spatial match filters, with each filter designed to reconstruct the image along one A-line. The method is evaluated through simulations with the Field II program using a linear array. The receiving array employs a conventional delay and sum beamformer followed by a bank of compression filters matched to the echo signal sample (ESS), each filter associated with echoes from a specific direction. Simulation results revealed that this approach generates higher lateral resolution and relatively lower range sidelobe amplitudes, as compared with other compression schemes, acceptable for many industrial and medical imaging applications without time weighting. Further sidelobe reduction was achieved through applying Taylor weighting function without considerable sacrificing axial resolution whereas the highest sidelobe was lower than 60 dB. Additionally an eSNR improvement about 20 dB can be expected in comparison with conventional pulsing technique.