基于分数阶Fourier变换的线性调频超声回波信号的滤波李进.pdf

2008, 27(4):231～ 235 　　Journal of Biomedical Engineering Research Fourier ＊ ■ 李进,郑驰超,彭虎 (中国科学技术大学 电子科学与技术系, 合肥 230027) :编码超声发射技术已在高 超声成像仪中使用, 其中线性调频信号是常用的编码信号。 由于通过 超声系统的回波会有较大衰减, 接收信号通常比较微弱, 并且带有强噪声, 影响成像质量。分数阶Fourier 变 换应用在编码超声信号处理中, 可以有效提高成像质量。本研究提出一种新的成像方法, 先对回波信号进行 分数阶Fourier 变换, 再经带通滤波器滤除大部分噪声, 然后通过匹配滤波器处理, 最后成像。该方法同时融 合了信号在时域和频域的信息, 并可以进一步降低发射功率。仿真结果表明, 这种方法相对于传统的成像方 法可以进 一步增强系统的抗干扰能力, 提高信噪比, 从而改善超声成像质量。 :分数阶傅立叶变换;线性调频信号;匹配滤波器;超声滤波;信噪比 :R318　　:　　:1672-6278 (2008)04-0231-05 Filtering of Chirped Ultrasound Echo Signals with the Fractional Fourier Transform LI Jin, ZHENG Chichao, ENG Hu (Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China) Abstract:Coded ultrasound transmit technology is generally used in high-end ultrasound imaging device.Linear frequency modifing signal is one of the most commonly used coded ultrasound signal.Because the ultrasound attenuate heavily, the received signal is very weak and accompanies with strong noise, which infects the quality of image.The fractional Fourier transform (FrFT)has some advantages over conventional matched filtering techniques in applications of coded ultrasound signal.FrFT can improve the imaging quality greatly in coded ultrasound. new imaging methodwas presented in the paper, after doing FrFT, we used band passfilter to filter most of the noise, and then matched filter to get the image.By using time and frequency information at the same time, the fractional Fourier method could lower transmission power.Our simulation results prove this by showing good performances withhigher SNR, and improve ultrasound imaging quality. Key words:Fractional Fourier transfo