一种新型自适应动态滤波器在超声成像中的应用

摘要

目的 为使动态滤波器的中心频率可实时匹配回波信号中心频率,本文设计了一种新型的自适应动态滤波器.方法 本文自适应机制是以快速傅里叶变换(fast Fourier transform,FFT)算法实时分析真实回波信号的频率特性,根据频率编号自适应匹配动态滤波器的系数.该滤波器的所有模块基于现场可编程门阵列(field programmable gate array,FPGA)硬件实现,最后将加入白噪声的正弦信号使用Modelsim时序仿真工具进行仿真.结果 仿真结果表明,这种滤波器能良好匹配回波信号中心频率,消除噪声.结论 本文提出的自适应动态滤波器满足高速实时系统的要求,为超声系统中滤波器的设计提供了可靠依据.%Objective A new self-adaptive dynamic filter in ultrasound imaging system was proposed to match the center frequency of the dynamic filter and the real echo in real time. Methods The tast Fourier transtorm(FFT) processor was used to analyze each small section of the echo and the frequency characteristic of the real echo deciding the factors of the filter in the self-adaptive mechanism. The realization of the system based on field programmable gate array(FPGA) was analyzed and the design was carried on by Modelsim as the timing simulation tool dealing with sinusoidal signals doped with white noise. Results The simulation results showed that the self-adaptive dynamic filter could reduce the noise strongly as the method could match the center frequency of the near field and far field real echo precisely. Conclusions The new self-adaptive dynamic filter is tast enough tor processing high-speed and real-time signals,providing one basis tor designing the filter in ultrasongraphy.