*3.2.1. 2R-SAFT architecture*

12 Breakthroughs in Ultrasound Imaging

254 Advancements and Breakthroughs in Ultrasound Imaging

and TFM

in the market.

**3.2. Acquisition subsystem**

**Figure 9.** Experimental images from tissue phantom. (a) 2R-SAFT + Golay, (b) 2xA-SAFT + Golay , (c) Lateral profiles comparison between 2R-SAFT + Golay and 2xA-SAFT + Golay, (d) 4xA-SAFT + Golay, (e) 8xA-SAFT + Golay, (f) Lateral profiles comparison between 4xA-SAFT and 8xA-SAFT + Golay , (g) 16xA-SAFT + Golay, (h) TFM , (i) Lateral profiles comparison between 16xA-SAFT

In this section, two acquisition architectures are exposed. On one hand, a minimal system for 2R-SAFT strategy which allows a low-cost and small imaging system and, in the other hand, the architecture which implements 8xA-SAFT plus Golay encoding strategy and uses more hardware but yields better quality images. Which strategy to use depends on the concrete application. Any of these configurations can be carried out using boards systems available As we study in section 2.1.1, it is basically composed of one channel in emission and two channels in reception. Figure 11 shows the complete architecture for 2R-SAFT implementation. As we can see, a multiplexer is connected to the transmission channel for sequentially activate each element as an emitter, and a second multiplexer will be on charge of connecting the selected elements to both reception channels.

All the acquisition process is managed by a hardware control system which is located in a field-programmable gate array (FPGA). In addition, a local memory is also used to store every received signal. Finally, the signals are transferred to the imaging system using any communication interface (USB, Ethernet, PCI Express). In the imaging system, raw data is stored in a RAM memory of 2*N* − 1 signals of capacity to be used for compose and beamform the ultrasonic images using a GPU.
