SoC-Based Architecture for an Ultrasonic Phased Array With Encoded Transmissions

This work presents a SOC-based (system-on-chip) architecture for ultrasonic imaging systems in airborne transmission which uses macro-sequences derived from complementary sets of sequences (CSS) to achieve simultaneous beam steering in several directions. By means of CSS concatenation and zero padding, a new macro-sequence can be obtained which achieves zero auto-and cross-correlation zones (ZCZ). These zones can be adjusted to provide interference-free CDMA (code division multiple access) within the scanning area. The correlation results with the proposed macro-sequences provide the A-scan lines for a final B-scan image. In contrast to other encoding schemes with similar sizes of ZCZ, the one proposed here allows an architecture design that further minimizes the computational load to make real-time processing feasible. The implementation of the proposed architecture in a FPGA (field-programmable gate array) device, including all the stages from the emission and reception modules of the imaging ultrasonic system, is presented. The ultrasonic phased array has 8 elements and permits the simultaneous analysis of 32 different angular sectors, for a maximum range of 1.5 m and an angular aperture of +/- 64 degrees.