METHODS FOR ESTIMATION OF SUBSAMPLE TIME DELAYS OF DIGITIZED ECHO SIGNALS
METHODS FOR ESTIMATION OF SUBSAMPLE TIME DELAYS OF DIGITIZED ECHO SIGNALS
复制标题
DOI：
10.1006/uimg.1995.1007
复制
发表时间：
1995-04-01
影响因子：
2.3
通讯作者：
SPRATT, S
中科院分区：
文献类型：
--
作者：
CESPEDES, I;HUANG, Y;SPRATT, S
时延估计（TDE）在实践中通常通过数字化回波信号的互相关来执行。由于时间延迟通常不是采样周期的整数倍，因此互相关函数（ccf）的最大样本的位置是峰值位置的不精确估计。因此，必须在ccf的样本之间进行插值以提高估计精度。使用理论和模拟，我们审查和比较几种方法的性能插值的ccf。插值的最大似然方法是将重构滤波器应用于离散ccf。然而，这种方法在实践中只能近似，并且可能是计算密集型的。由于这些原因，一个简单的方法被广泛使用，包括拟合抛物线（或其他曲线）的样本ccf在其峰值附近。我们描述和比较两种曲线拟合方法：抛物线和余弦插值。曲线拟合插值会产生有偏差的时延估计，这可能会妨碍这些方法在某些应用中的使用。讨论了这些误差对弹性成像的影响。我们证明了重建插值是无偏的。提出了一种迭代实现的重建过程，可以显着减少计算时间。(C)出版社：Academic Press
Time delay estimation (TDE) is commonly performed in practice by crosscorrelation of digitized echo signals. Since time delays are generally not integral multiples of the sampling period, the location of the largest sample of the crosscorrelation function (ccf) is an inexact estimator of the location of the peak. Therefore, one must interpolate between the samples of the ccf to improve the estimation precision. Using theory and simulations, we review and compare the performance of several methods for interpolation of the ccf. The maximum likelihood approach to interpolation is the application of a reconstruction filter to the discrete ccf. However, this method can only be approximated in practice and can be computationally intensive. For these reasons, a simple method is widely used that involves fitting a parabola (or other curve) to samples of the ccf in the neighborhood of its peak. We describe and compare two curve-fitting methods: parabolic and cosine interpolation. Curve-fitting interpolation can yield biased time-delay estimates, which may preclude the use of these methods in some applications. The artifactual effect of these bias errors on elasticity imaging by elastography is discussed. We demonstrate that reconstructive interpolation is unbiased. An iterative implementation of the reconstruction procedure is proposed that can reduce the computation time significantly. (C) 1995 Academic Press, Inc.