Spatial processing for coherent noise reduction in ultrasonic imaging
Spatial processing for coherent noise reduction in ultrasonic imaging
复制标题
超声成像中相干降噪的空间处理
DOI：
10.1121/1.398887
复制
发表时间：
1990
影响因子：
2.4
通讯作者：
J. Saniie
中科院分区：
文献类型：
--
作者：
N. Bilgutay;R. Murthy;U. Bencharit;J. Saniie
当目标接收时存在由大量介质固有的复杂和随机分布的散射体引起的相干噪声时，系统区分两种类型信号的能力往往成为最关键的性能考虑因素。能够抑制时变（非相干）噪声的传统技术通常在噪声是时不变（相干）时无效。近年来，分集技术已经发展到可以通过改变发射频率或换能器的位置来实现相干噪声项的去相关。虽然分集技术在与传统的平均算法结合使用时提供了一些噪声抑制，但仅靠这种线性技术不能充分利用其潜在的好处。本文提出了一种基于空间去相关信号极性的非线性检测方案。理论和实验结果表明，极性阈值算法提供的目标增强远远优于先前在空间处理中使用的线性技术。此外，本文还研究了实验数据的空间去相关特性，以确定数据采集和信号处理所需的参数。
When the target is received in the presence of coherent noise resulting from a large number of complex and randomly distributed scatterers inherent to the medium, the ability of the system to distinguish between the two types of signals often becomes the most crucial performance consideration. Conventional techniques that are capable of suppressing time‐varying (incoherent) noise are generally not effective when the noise is time invariant (coherent). In recent years, diversity techniques have been developed that allow the decorrelation of the coherent noise term by altering either the transmitted frequency or the position of the transducer. Although the diversity techniques provide some noise suppression when used in conjunction with the conventional averaging algorithms, their potential benefits cannot be fully exploited by such linear techniques alone. In the work presented here, a nonlinear detection scheme based on the polarity of the spatially decorrelated signals is examined. The theoretical and experimental results indicate that the polarity‐thresholding algorithm provides target enhancement that is far superior to the linear techniques previously used in spatial processing. Furthermore, the paper examines the spatial decorrelation properties of the experimental data to determine the desirable parameters for data acquisition and signal processing.