Squint-mode InISAR imaging based on nonlinear least square and coordinates transform

Abstract

Aiming at the interferometric inverse synthetic aperture radar (InISAR) imaging in the presence of squint, we investigate the influence of squint on the InISAR imaging. First, coupling of the squint additive phase and the target azimuth/altitude coordinates to be solved may make the solution more difficult. Second, the squint angle may lead to estimation error of the vertical coordinates and distortion of the ultimate image. Traditional InISAR imaging algorithms can not solve the above two problems effectively, so we propose a new method which combines the nonlinear least square (NLS) and coordinates transform (CT) to estimate the target coordinates, and a three-dimensional (3-D) image consistent with the real target is obtained accordingly. Simulations show that the proposed method is effective for the squint-mode InISAR imaging. interferometric inverse synthetic aperture radar (InISAR), three dimensional (3-D) imaging, squint mode, nonlinear least square (NLS), coordinates transform (CT)Citation:Liu C L, He F, Gao X Z, et al. Squint-mode InISAR imaging based on nonlinear least square and coordinates transform.

Interferometric inverse synthetic aperture radar imaging for space targets based on wideband direct sampling using two antennas

“…(11) and (18), the true X coordinate can be written as (11) and (18), the true X coordinate can be written as…”

“…In order to enhance the target recognition probability, the interferometric ISAR (InISAR) [6][7][8][9][10][11][12] technique is presented to achieve the third dimension of the target. In traditional InISAR imaging systems, three receiving antennas are commonly used.…”

“…Wang et al concentrated on the signal model and motion compensation of moving target 3-D imaging using the InISAR method. 11 The computation efficiency is decreased since NLS is applied. 7 Reference 8 founded the motion model and used the 3-D motion parameter estimation to carry out image registration.…”

Squint model interferometric ISAR imaging based on respective reference range selection and squint iteration improvement

“…We call this situation in InISAR imaging as ‘normal model’. However, in real application, targets are usually far away from the antenna axis [16–18]. It is called as ‘squint mode’ accordingly.…”

“…In literature [17], the approximation adopted to solve the coupling of target coordinates and accessional phase induced by squint model degrades the quality of 3D imaging results. Literature [18] combines the non‐linear least square and coordinates transform (CT) to carry out the reconstruction of the target's 3D coordinates. However, the application of non‐linear least square decreased the computation efficiency.…”