基于DDS和FPGA的数字式多脉冲激励超声检测系统设计

Design of digital multi-pulse excitation ultrasonic testing system based on DDS and FPGA

针对现有超声波检测系统发射脉冲单一、设计复杂等不足,设计一个以现场可编程门阵列(FPGA)为核心的数字式超声检测系统。采用直接数字合成(DDS)技术,通过可编程方式控制超声波激励信号的产生。检测系统能够针对不同检测需要,灵活设置和选择不同波形、频率、脉冲宽度和脉冲数的激励信号,从而提高检测能力和适应性。试验结果表明:多脉冲激励方式能够在较低的激励电压下,获得更强的超声回波信号,实现工件内部更深范围内缺陷的有效检出。

A digital ultrasound detection system based on field programmable gate array（FPGA）was designed in view of the deficiency of the current ultrasonic testing system such as single transmission pulse and complicated design. The system adopts direct digital synthesis（DDS）technology and programmable controlling method to control the generation of ultrasonic excitation signals. The excitation signals of different waveforms, frequencies, pulse widths and pulse numbers can be flexibly set and selected for different testing demands, thus improving the capability and adaptability of detection. The experiment results show that much stronger ultrasonic echo signals can be obtained at a lower excitation voltage and the defects within a deeper range of the workpiece interior can be detected through this multi-pulse excitation method.