The research of compression and generation of high-precision dynamic focusing delay data for ultrasound beamformer

In an ultrasound imaging system, dynamic focusing is crucial in improving the spatial resolution and signal-to-noise ratio. However, the generation of focusing delay data (FDD) requires complex calculations and a large amount of memory. The dynamic focusing system may become extremely complex as the number of focusing channels and the focal depth increase. This paper presents a simplified scheme of a high-precision generator for the FDD in Field-programmable Gate Array (FPGA). First, the original FDD are pre-calculated, quantized, decomposed, and compressed by exploiting the recursive characteristics between focusing channels. Then, the initial value and changing locations of each channel are stored as a reference data set. Finally, the FDD are generated in real time by decompressing the preloaded reference data set during the focusing process. The results indicate that the proposed approach consumes less than 1% of the memory space of the original method, which may provide significant resource savings and low hardware power consumption. The proposed method can also be applied to convex or flat transducers array in compact beamformers. Moreover, the focusing accuracy and compression ratio can be flexibly adjusted, and the compression ratio can be further improved when the proposed approach is combined with the dynamic aperture. The proposed approach is contribute to the solution of the problem of the complex and large amount of data in ultrasonic imaging system. It is suitable for designing a specific compact focusing beamformer, particularly for a portable ultrasound imaging system.