船只目标三维转动对SAR成像影响的定量分析

Quantitative analysis of the influence of three-dimensional rotations of ship targets on SAR imaging quality

摘要:

在分析船只三维转动（横滚、俯仰、偏航）对合成孔径雷达（Synthetic Aperture Radar，SAR）成像质量的影响方面，现有文献只考虑了仅存在一维转动时的影响，未考虑三维转动同时存在时对SAR成像质量的影响。另外，现有文献主要基于船只转动对船只散射点瞬时多普勒频率的影响进行分析，并未真正与对SAR图像质量的影响关联起来。本文推导了适用于船只存在三种一维转动、同时存在三维转动时的SAR图像二维时域表达式，以及散射点方位向坐标的表达式。在上述表达式的基础上，通过分析船只上的散射点在SAR图像中的偏移情况，扩展到分析船只整体在SAR图像中的形变情况；通过分析一维转动对SAR成像的影响，扩展到分析三维转动同时存在时对SAR成像的影响。研究表明：船只三维转动引入了包络误差和相位误差，导致SAR图像中散射点模糊并在方位向偏移，且不同散射点的偏移量不同，从而使船只形状发生畸变。仿真结果验证了所推导表达式的准确性及理论分析的正确性。

Abstract:

In terms of analyzing the effect of a ship’s three-dimensional rotations including the roll, the pitch and the yaw on imaging quality of synthetic aperture radar(SAR), the existing literatures only consider the effect when only one-dimensional rotation exists, and do not consider the effect when three-dimensional rotations exist simultaneously. In addition, the existing literatures mainly analyze the effect of the ship rotation on the instantaneous Doppler frequency of a scatterer on the ship, which is not directly related to the effect on SAR image quality. This paper derives two-dimensional time-domain expression of the SAR image and the expressions of azimuth coordinates of ship scatterers when there are only one kind rotation or three-dimensional rotations at the same time. Based on the derived formula, after analyzing the offset of the scatterer on the ship in the SAR image, we analyze the deformation of the whole ship in the SAR image. After analyzing the influence of one-dimensional rotation on SAR imaging, we analyze the influence of three-dimensional rotations on SAR imaging. The research shows that the three-dimensional rotations of the ship introduces envelope error and phase error, which causes the scattering points in the SAR image to be blurred and shift in azimuth, and different scattering points have different offsets, so that the shape of the ship is distorted. The simulation results verify the accuracy of the derived expressions and the correctness of the theoretical analysis.