By using digital processing techniques and by exploiting a new technology which became available only recently, a radically new approach to synthesizing ultrasonic images in real time has become feasible. The most striking features of this alternative imaging scheme are: real-time imaging, 8 bit quantization, improved fidelity, variable resolution and point-shaped mapping.
E. Schuster, E. Schuster,
"A New Digital Approach To Synthesizing Ultrasonic Images In Real-Time", Proc. SPIE 0375, Medical Imaging and Image Interpretation, (1 November 1982); doi: 10.1117/12.934645; https://doi.org/10.1117/12.934645