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中文摘要: 在传统超声成像的动态滤波器设计中，需首先按线性声场模型计算出近场及远场回波的中心频率，据此确定出动态滤波器在接收过程中各段的滤波器系数。但这种方式有许多与实际不符的假设，这造成了动态滤波器并不能很好的匹配真实回波，降低了图像的分辨率及灵敏度。为了解决这个问题，文章设计了一种自适应的动态滤波器，利用FFT变换，实时的分析各小段真实回波的频率特性，根据真实回波的频率特性选择不同的动态滤波器系数。实验证明，此种方法能够在保持图像的分辨率的同时提高图像的灵敏度。
中文关键词: 超声，自适应，动态滤波器，分辨率，灵敏度
Abstract:In conventional ultrasound imaging system, the design of dynamic filter needs the center frequency of the near field and far field first, which were calculated using the linear sound field model. Then the frequencies are used to determine the factors of the dynamic filter for every section of the echo. As the method has several assumptions not according to the fact, the dynamic filter can’t match the real echo precisely. The resolution and the sensitivity of the picture were reduced. To circumvent the problem, an adaptive dynamic filter was proposed. In order to obtain the frequency characteristic of the real echo in real time, it uses the FFT algorithm to analysis the every small section of the echo. Then the frequency characteristic of the real echo decides the factors of the filter. The experiment proved that this method can improve the sensitivity of the picture while maintaining the resolution.
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