Application on Space-time Coding Technology in Ultrasonic Back-propagation Method

When applying the space-time coding technique into the ultrasound imaging system, the signal-to-noise-ratio (SNR) can be improved. However when the space-time coding combines with the conventional synthetic aperture techniques can result some ghost images because the conventional synthetic aperture technique cannot suppress the axial direction of the side-lobe which emerges after pulse compression and thereby reducing the image quality. To solve the problem of ghost imaging, this paper introduces a new method, which combines the techniques of space-time coding and ultrasonic back-propagation synthetic aperture. The main idea of the method is that different locations using different coding pulse emission. It can be achieved by using the Truncated long code[1]. The synthetic aperture technique based on the ultrasonic back-propagation is then applied for processing the echo signals to further improve the SNR as well as suppress the axial side-lobe. The crosstalk among echo signals can also be reduced. Simulation shows positive results of the new method. Both detection sensitivity and robustness against noise are improved and overall performance of the image system is enhanced.