High Frame Rate Synthetic Aperture Ultrasound Imaging Using Mismatched Coded Excitation Waveform Engineering: A feasibility study.

Mismatched coded excitation can be employed to increase the frame rate of synthetic aperture ultrasound imaging. The high auto-correlation and low cross-correlation of the transmitted signals enables the identification and separation of the signal sources at the receiver. Thus, the method provides B-mode imaging with simultaneous transmission from several elements and capability of spatial decoding of the transmitted signals which makes the imaging process equivalent to consecutive transmissions. Each transmission generates its own image and the combination of all the images results in a image with a high lateral resolution. In this paper, we introduce two different methods for generating multiple mismatched coded excitations with identical frequency bandwidth and code length. Therefore, the proposed families of mismatched coded excitations are able to generate similar resolutions and signal-to-noise ratios. The application of these methods is demonstrated experimentally. Furthermore, several techniques are suggested that can be used to reduce the cross-correlation between the mismatched codes.