Ivanenko Yevhen, Vu Viet T, Batra Aman, Kaiser Thomas, Pettersson Mats I
Department of Mathematics and Natural Sciences, Blekinge Institute of Technology, 371 79 Karlskrona, Sweden.
Institute of Digital Signal Processing, University of Duisburg-Essen, 47057 Duisburg, Germany.
Sensors (Basel). 2022 Jun 30;22(13):4941. doi: 10.3390/s22134941.
Time-domain backprojection algorithms are widely used in state-of-the-art synthetic aperture radar (SAR) imaging systems that are designed for applications where motion error compensation is required. These algorithms include an interpolation procedure, under which an unknown SAR range-compressed data parameter is estimated based on complex-valued SAR data samples and backprojected into a defined image plane. However, the phase of complex-valued SAR parameters estimated based on existing interpolators does not contain correct information about the range distance between the SAR imaging system and the given point of space in a defined image plane, which affects the quality of reconstructed SAR scenes. Thus, a phase-control procedure is required. This paper introduces extensions of existing linear, cubic, and sinc interpolation algorithms to interpolate complex-valued SAR data, where the phase of the interpolated SAR data value is controlled through the assigned a priori known range time that is needed for a signal to reach the given point of the defined image plane and return back. The efficiency of the extended algorithms is tested at the Nyquist rate on simulated and real data at THz frequencies and compared with existing algorithms. In comparison to the widely used nearest-neighbor interpolation algorithm, the proposed extended algorithms are beneficial from the lower computational complexity perspective, which is directly related to the offering of smaller memory requirements for SAR image reconstruction at THz frequencies.
时域反投影算法广泛应用于最先进的合成孔径雷达（SAR）成像系统中，这些系统是为需要运动误差补偿的应用而设计的。这些算法包括一个插值过程，在此过程中，基于复值SAR数据样本估计一个未知的SAR距离压缩数据参数，并将其反投影到一个定义好的图像平面中。然而，基于现有插值器估计的复值SAR参数的相位不包含关于SAR成像系统与定义图像平面中给定空间点之间距离的正确信息，这会影响重建SAR场景的质量。因此，需要一个相位控制过程。本文介绍了现有线性、三次和 sinc 插值算法的扩展，用于对复值SAR数据进行插值，其中通过分配先验已知的距离时间来控制插值后的SAR数据值的相位，该距离时间是信号到达定义图像平面的给定点并返回所需的时间。在太赫兹频率下，以奈奎斯特速率在模拟数据和真实数据上测试了扩展算法的效率，并与现有算法进行了比较。与广泛使用的最近邻插值算法相比，从较低的计算复杂度角度来看，所提出的扩展算法是有益的，这与在太赫兹频率下SAR图像重建所需的较小内存要求直接相关。
