A Research On The Implementation Of Acoustic Array Multi-Beamforming Based On FPGA

Beam-forming system is a key part of sonar system, it can focus signal's energy on a specific direction to increase transmission distance in source-end, also can increase SNR? track target in the sink-end, so the research on beam-forming is of importance to sonar system such as under-water detector?under-water weapon. Under non-real-time occasion, people can collect data only on site and then process in lab; however, on real-time occasion, beam-forming function should be implemented in hardware, and its speed is always a bottleneck of system's performance.People used DSP or ARM to design beam-forming system before FPGA being improved, the defect is:Numerous of chips is needed and then makes the circuit complicated and cost expensively; furthermore, chips CPU can only execute program in sequence. These defects make the systems' speed and parallelism not ideal under large-scale signal processing occasion, so people use FPGA instead.The main point of this thesis is to design a system including a hardware which perform real-time beam-forming and a software which can display result in time, so people can use this system to scan underwater target in any direction in time. FPGA is the core of the hardware, the author adopt "FPGA+AD+USB" scheme to design the system, use Verilog to implement it and then makes it a real-time and small volume.The main work includes:analyze and simulate multiple beam-forming algorithms, and then research their pros and cons when using FPGA to implement them; design and debug the hardware; research data-sheets to understand chips' principle and procedure, then design correct read write timing and use Verilog to implement it; decompose phase-shift multi-beamforming algorithm and then implement it in FPGA; design a software which can collect data?correct data and display data in time.After multiple experiments in the acoustical pool, the author verify the correctness of system's function and quantity its performance statistically, the result indicates that it satisfy the expected goal. Also the author use weighted method to improve its performance, the result indicates the method can decrease the amplitude of side-lobe; and then the author place two transducers in the acoustical pool to analyze its ability to detect multiple targets, the result indicates that the system possesses the ability.