基于叠加法消除CMUT测量拖尾的研究

Elimination of ultrasonic tailing based on the superposition method

介绍了一种针对空气耦合电容式微加工超声传感器(CMUT)近场盲区的消除方法。从CMUT传感器本身的工作原理出发,通过计算CMUT传感器的集中等效参数建立了CMUT的弹簧-质量-阻尼等效模型,根据此模型分析了CMUT传感器拖尾信号产生的原因、激励脉冲宽度与拖尾信号的长度和能量的关系等;设计了反相叠加激励信号,证明了叠加法对消除CMUT拖尾信号的有效性;设计了由FPGA、信号驱动电路、信号提取电路、信号采集卡构成的测试系统;实验测试显示,该方法可以有效地改善CMUT传感器的盲区范围。

A method aiming at eliminating the ultrasonic tailing in the output signals of a capacitive micromachined ultrasonic transducer(CMUT)was proposed the principle of CMUT was introduced,and an equivalent mass-spring-damper model was established by equivalently lumping the parameters of the CMUT.The reason of the appearance of CMUT’s tailing signal was explained and the relationship between the pulse width and the length of the tailing signal was analyzed.An opposite phase excitation signal was designed,and the effectiveness of the superposition method was proved.A test system was designed,containing a FPGA,a signal drive circuit,a signal extraction circuit and a signal acquisition card.The experiments verify the effectiveness of the method for decreasing blind zones.