Abstract
Downward‐looking linear array synthetic aperture radar (DLLA SAR) is a kind of three‐dimensional (3‐D) radar imaging system. To obtain the superresolution along the crosstrack direction of DLLA SAR, the sparse regularization models with single measurement vector (SMV) have been widely applied. However, the robustness of the sparse regularization models with SMV is unsatisfactory, especially in the low signal‐to‐noise rate (SNR) environment. To solve this problem, we proposed a novel imaging method for DLLA SAR based on the multiple measurement vector (MMV) model with L2,1‐norm. At first, we exchange the processing order between the along‐track (AT) domain and the crosstrack (CT) domain to keep the same sparse structure of the signal in the crosstrack domain so that we can establish the imaging problem as a sparse regularization model based on the MMV model. Moreover, the mixed L2,1‐norm is introduced into the regularization term of the MMV model. Finally, the modified orthogonal matching pursuit (OMP) algorithm is designed for the MMV model with the L2,1‐norm. The simulations verify that the proposed method has better performance in the lower SNR environment and requires lower computation compared with the conventional methods.
Highlights
Synthetic aperture radar (SAR) has been widely applied in the field of remote sensing to obtain radar images without being affected by weather, daylight, or cloud coverage [1, 2]
We propose a novel imaging method for Downward-looking linear array (DLLA) 3D SAR based on the measurement vector (MMV) model with L2,1-norm
The imaging problem can be transformed into a sparse regularization model based on the MMV model since we construct the same CT sparse structure of different pulses by exchanging the processing sequence of the CT compression and the AT compression
Summary
Synthetic aperture radar (SAR) has been widely applied in the field of remote sensing to obtain radar images without being affected by weather, daylight, or cloud coverage [1, 2]. Downward-looking linear array (DLLA) SAR generates 3-D radar images by using a linear array along the wings to illuminate the overflown scene [6, 7]. By modifying the traditional SAR imaging algorithms, 3-D imaging algorithms for DLLA SAR based on range-Doppler (RD) [8], chirp scaling [9], and polar formatting [10] are proposed. For these imaging algorithms, the resolutions in range, along-track (AT), and crosstrack (CT) directions are obtained by pulse compression, synthetic aperture, and beam-forming, respectively.
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