TY - JOUR
T1 - Spaceborne High-Squint High-Resolution SAR Imaging Based on Two-Dimensional Spatial-Variant Range Cell Migration Correction
AU - Ding, Zegang
AU - Zheng, Pengnan
AU - Li, Han
AU - Zhang, Tianyi
AU - Li, Zhe
N1 - Publisher Copyright:
© 2022 IEEE.
PY - 2022
Y1 - 2022
N2 - High-squint imaging is an effective means to enhance the flexibility and coverage ability of spaceborne synthetic aperture radar (SAR). Although existing imaging algorithms based on linear range cell migration correction (LRCMC) and nonlinear chirp scaling (NCS) can reduce the range-azimuth coupling of the spectrum and the spatial variant of the Doppler parameter to some extent, they become invalid as the resolution increases. On one hand, the beam rotation of sliding spotlight SAR results in nonlinear azimuth variant of the Doppler center, and the traditional deramping operation, which removes the linear variation, will cause spectrum aliasing. On the other hand, these algorithms assume that the azimuth variants of range cell migration (RCM) are consistent in the total swath. However, the azimuth variants of RCM are different in different range cells, which cannot be neglected in high-resolution imaging. To solve these problems, a novel imaging algorithm based on 2-D spatial-variant RCM correction is proposed in this article. First, LRCMC is utilized, and the nonlinear azimuth deramping operation is conducted to obtain an aliasing-free spectrum. Then, the azimuth variant of RCM is corrected by azimuth interpolation and polynomial compensation. Noting that the interpolation coefficient varies linearly with slant range, this can weaken the azimuth variant differences of RCM in different range cells. Meanwhile, azimuth polynomial compensation can correct the consistent azimuth variant of RCM, and hence, the azimuth variant of RCM can be totally corrected. Finally, the compression is performed via the range chirp scaling and azimuth NCS. The effectiveness of the proposed algorithm is verified by computer simulations.
AB - High-squint imaging is an effective means to enhance the flexibility and coverage ability of spaceborne synthetic aperture radar (SAR). Although existing imaging algorithms based on linear range cell migration correction (LRCMC) and nonlinear chirp scaling (NCS) can reduce the range-azimuth coupling of the spectrum and the spatial variant of the Doppler parameter to some extent, they become invalid as the resolution increases. On one hand, the beam rotation of sliding spotlight SAR results in nonlinear azimuth variant of the Doppler center, and the traditional deramping operation, which removes the linear variation, will cause spectrum aliasing. On the other hand, these algorithms assume that the azimuth variants of range cell migration (RCM) are consistent in the total swath. However, the azimuth variants of RCM are different in different range cells, which cannot be neglected in high-resolution imaging. To solve these problems, a novel imaging algorithm based on 2-D spatial-variant RCM correction is proposed in this article. First, LRCMC is utilized, and the nonlinear azimuth deramping operation is conducted to obtain an aliasing-free spectrum. Then, the azimuth variant of RCM is corrected by azimuth interpolation and polynomial compensation. Noting that the interpolation coefficient varies linearly with slant range, this can weaken the azimuth variant differences of RCM in different range cells. Meanwhile, azimuth polynomial compensation can correct the consistent azimuth variant of RCM, and hence, the azimuth variant of RCM can be totally corrected. Finally, the compression is performed via the range chirp scaling and azimuth NCS. The effectiveness of the proposed algorithm is verified by computer simulations.
KW - Azimuth deramping
KW - high squint
KW - nonlinear chirp scaling (NCS)
KW - spaceborne synthetic aperture radar (SAR)
KW - spatial-variant range cell migration (RCM) correction
UR - http://www.scopus.com/inward/record.url?scp=85142844650&partnerID=8YFLogxK
U2 - 10.1109/TGRS.2022.3222230
DO - 10.1109/TGRS.2022.3222230
M3 - Article
AN - SCOPUS:85142844650
SN - 0196-2892
VL - 60
JO - IEEE Transactions on Geoscience and Remote Sensing
JF - IEEE Transactions on Geoscience and Remote Sensing
M1 - 5240114
ER -