Abstract
High resolution synthetic aperture radar (SAR) imaging has extensive application value especially in military reconnaissance and disaster monitoring. The motion of the satellite during the transmission and reception of the signal introduces notable errors in the high resolution SAR spotlight mode, which will lead to a defocused SAR image if not handled. To address this problem, an accurate correct echo model based on non-start-stop model is derived to describe the property of the SAR signal in the paper. Then, in the imaging processing, an azimuth-time-varying range frequency modulation rate is used for range compression. The range history and compensation phase are also derived based on the correct echo model. Then, combining the correct echo model and Cartesian factorized backprojection (CFBP) algorithm, a modified CFBP algorithm is proposed for SAR imaging to improve the accuracy and efficiency of processing. Besides, the influence of residual error due to mismatch is analyzed in detail. In the end, the simulation experiment and Gaofen-3 (GF-3) data experiment are carried out to demonstrate the feasibility of the proposed algorithm.
Highlights
Synthetic aperture radar (SAR), which can provide remote sensing images during the day and night regardless of weather conditions, plays an important role in Earth and planetary observation [1,2,3]
The range history and compensation phase are derived for imaging processing
To show the effectiveness of the proposed algorithm, the simulation experiment and GF-3 data experiment are performed
Summary
Synthetic aperture radar (SAR), which can provide remote sensing images during the day and night regardless of weather conditions, plays an important role in Earth and planetary observation [1,2,3]. High resolution SAR imaging attracts growing interest due to its wide applications especially in military reconnaissance and disaster monitoring [4,5,6,7,8,9,10]. Several spaceborne SAR systems have the ability of submeter imaging. The COSMO-SkyMed SAR can achieve a high azimuth resolution better than 0.9 m [6], while TerraSAR-X can achieve 0.16 m azimuth resolution [7]. The Gaofen-3 (GF-3) satellite, a C-band multi-polarization SAR of China launched in 2016, can achieve 0.4 m azimuth resolution [5,10]. The realization of high resolution SAR imaging puts forward new requirements to the hardware of SAR system and poses new challenges to the imaging algorithm
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