MOtion COmpensation (MOCO) is the key to acquisition of high quality images by the airborne Synthetic Aperture Radar (SAR). In ultra-high resolution imaging, it is still a great challenge to correct space-variant motion errors accurately and efficiently. In this paper, an improved approach for multi-level space-variant MOCO with multi-level processing is proposed, which gives consideration to both precision and efficiency. First, the one-step MOCO algorithm is used to correct the range-variant component of the motion error effectively, avoiding inducing additional Range Cell Migration Correction (RCMC) error. Meanwhile, on the premise that the accuracy of phase correction should be guaranteed, the conventional calculation formula for line-of-sight range displacement is revised, and an approximate range envelope compensation without complex interpolation can be implemented with the subswath. Then, the subswath is used to reduce the range variance of the residual azimuth-variant error, as well as the influence of the error on the azimuth-to-frequency mapping. Consequently, the focusing effect in the case of wide beam is improved observably, and the computational burden of the aperture-dependent compensation algorithm is also reduced. The proposed approach can attain 0.1 m resolution, being useful in engineering practice. Simulations of point targets and processing of test data have validated the present research.
YANG Mingdong
,
YU Xiang
,
ZHU Daiyin
. High-precision space-variant motion compensation with multi-level processing for airborne SAR based on subswath[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2018
, 39(2)
: 321557
-321557
.
DOI: 10.7527/S1000-6893.2017.21557
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