Analysis Method of Errors (Motion and Atmospheric) in Synthetic Aperture Radar (SAR) Images

Abstract

Abstract.A method to allow the analysis of the effects of motion and atmospheric errors in SAR images is here presented. The objective of the method is to allow the visualization of the effects of motion errors and atmospheric artefacts on the processed (focused) SAR image. The method is intended to allow the analysis of the interaction of motion and atmospheric errors with the adopted SAR processing procedure and motion compensation algorithms. In this article the analysis method has been applied and tested to a C-Band E-SAR (DLR airborne SAR system) data set where we see that the effects of linear and non-linear phase errors observed are in agreement with the theory.

Antenna motion errors in bistatic SAR imagery

“…Due to the squint-look 4 in the current SAR configuration, as shown in figure 4, where the bistatic look-direction Ξ ˆand transverse look-direction Ξ ˙are not along the vertical and horizontal directions, we see that the target positioning error has both evident vertical and horizontal components as expected, as shown in figure 8. For instance, the dominant linear transverse smearing due to a quadratic trajectory error leads to linear position errors in both vertical and horizontal directions, as shown in figure 8(b).…”

“…The black curves denote the analytic values and the blue curves denote the measured values. 4 At the central position over the aperture, the look-direction of the radar is not perpendicular to the direction of the antenna velocity [34].…”

“…The antenna trajectory errors and the resulting geometric distortions in reconstructed images have been studied before [1][2][3][4][5][6][7][8][9]. However, all of these studies [1][2][3][4][5][6][7][8][9] are limited to certain configurations and trajectory error models and rely on certain simplifying assumptions. [1][2][3][4][6][7][8] consider monostatic configuration and straight linear trajectory.…”

“…However, all of these studies [1][2][3][4][5][6][7][8][9] are limited to certain configurations and trajectory error models and rely on certain simplifying assumptions. [1][2][3][4][6][7][8] consider monostatic configuration and straight linear trajectory. [5] considers a bistatic configuration with straight linear transmitting and receiving antenna trajectories under far-field and small scene assumptions.…”

“…In this paper, we present a quantitative analysis of positioning errors in bistatic SAR imagery due to antenna trajectory errors. The antenna trajectory errors and the resulting geometric distortions in reconstructed images have been studied before [1][2][3][4][5][6][7][8][9]. However, all of these studies [1][2][3][4][5][6][7][8][9] are limited to certain configurations and trajectory error models and rely on certain simplifying assumptions.…”