RX beamforming is one of the critical section in the ultrasound imaging 
system. It processes the RF data from each receive elements and 
construct RF scan lines for later process. The ability to deal with huge 
data flaw and accuracy is essential. 

Point focus gives high resolution on the axile direction. Adaptive 
weighting during receive beamforming can also improve the resolution 
and overall image quality. 

FPGA is normally used here to do beamforming. As FPGA becomes 
more and more powerful, the cost per element drops dramatically. 

A sample digital beam forming block diagram is given bellow: