Airborne Squinted Spotlight SAR Imaging using Polar Format Algorithm

Shin, Hee-Sub; Jeon, Jae-Han; Lim, Jong-Tae

doi:10.1109/sice.2006.314766

Cited by 2 publications

(2 citation statements)

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“…Different filter functions are proposed aiming at different imaging conditions. Another method [34], [35], [36] is to divide the illuminated area into multiple subregions and apply different phase corrections to the phase history data before resampling processing. There are more literatures are readily available about corrections to the planar wavefront approximation error.…”

Section: Discussionmentioning

confidence: 99%

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Squint Spotlight SAR Imaging by Two-Step Scaling Transform-Based Extended PFA and 2-D Autofocus

Han

Zhu

Mao

2023

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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In this article, a novel imaging algorithm by combining two-step scaling transform (TSST) with structure-aided 2-D autofocus is proposed for the squint spotlight synthetic aperture radar (SAR). First, on the basis of planar wavefront assumption, a modified range-frequency linear scaling transform (MRFLST) and an azimuth-time nonlinear scaling transform (ATNST) are proposed to eliminate the coupling between range-frequency and azimuth-time of the received echo. Furthermore, to improve the efficiency, the MRFLST is implemented by using the principle of chirp scaling (PCS), which involves only complex multiplications and fast Fourier transforms (FFTs) without any interpolation, meanwhile, a constant scaling factor (CSF) selecting criteria is defined to avoid range spectrum aliasing. Then, to correct the phase error caused by the range measurement error and atmospheric propagation effects, the prior 2-D phase error structure implied in the TSST is analyzed. Finally, by integrating the derived 2-D phase error structure and range frequency fragmentation technique, a new 2-D autofocus algorithm is presented to improve the image quality. Simulated and real data experiments are carried out to verify the proposed algorithm. Index Terms-2-D autofocus, planar wavefront assumption, principle of chirp scaling (PCS), range frequency fragmentation, two-step scaling transform. I. INTRODUCTIONB ENEFITING from the unique all-weather and all-time detecting ability, synthetic aperture radar (SAR) becomes the popular and extensively adopted means in supervising and imaging interesting areas [1]. The spotlight mode SAR can provide us with high resolution through continuously adjusting the antenna beam of the radar pointing to a preselected district in time of the echo acquisition [2].The coherence of data processing over the whole aperture synthesis period is the assurance for getting a well-focused imaging result and the imaging processes require precise measuring positions of the radar footprints. However, the ubiquitous Manuscript

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Section: Discussionmentioning

confidence: 99%

“…It can be seen that the evident azimuth defocus is appeared in Fig. 23(a), and this degradation is well compensated by using the filter function-based SVPF (34).…”

Section: (N)mentioning

confidence: 99%