Spatially Variable Phase Filtering Algorithm Based on Azimuth Wavenumber Regularization for Bistatic Spotlight SAR Imaging Under Complicated Motion

Miao, Yuxuan; Yang, Jianyu; Wu, Junjie; Sun, Zhichao; Chen, Tianfu

doi:10.1109/tgrs.2021.3139965

Cited by 2 publications

(4 citation statements)

References 33 publications

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“…To mitigate the effects caused by the planar wavefront approximation, the space-variant post-filtering algorithm (SVPF) [31], [32], [33] is regarded as the typical approach to compensate for the image deterioration. Different filter functions are proposed aiming at different imaging conditions.…”

Section: Discussionmentioning

confidence: 99%

“…It should note that the location of the point target in the formed image is determined by the constant and linear terms, ΔR (0) and ΔR (1) of ΔR, ΔR (0) p and ΔR (1) p of ΔR p . According to [37], when the geometric distortion is considered in the approximate (33) where…”

Section: (N)mentioning

confidence: 99%

“…F = v cos θ s A Equation (33) gives the mapping relations between the real and the distorted locations of the targets. Then, the geometric distortion correction can be accomplished by resampling the distorted point from the wrong position (x, ŷ) to the right position (x p , y p ) to generate an undistorted image.…”

Section: (N)mentioning

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%

Section: (N)mentioning

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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“…By correcting the bistatic SAR 3D trajectories of the transmitter and the receiver with the estimated trajectory error, a well-focused BiSAR image could be achieved by performing imaging algorithms which are suitable for arbitrary motion, such as time-domain imaging algorithms [48,49] or generalized wavenumber-domain imaging algorithms [50,51].…”

Section: D Trajectory Error Estimationmentioning

confidence: 99%

An Estimation and Compensation Method for Motion Trajectory Error in Bistatic SAR

et al. 2022

Remote Sensing

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Bistatic synthetic aperture radar (BiSAR) has drawn increasing attention in recent studies benefiting from its ability for forward-looking imaging, its capability of receiver radio silence and its resistance to jamming. However, the motion trajectory error compensation of BiSAR is a challenging task due to multiple error sources and complex effects. In this paper, an estimation and compensation method for three-dimensional (3D) motion trajectory error of BiSAR is proposed. In this method, the Doppler error of multiple scattering points is estimated firstly by using the time–frequency analysis method. Next, a local autofocus process is introduced to improve the Doppler error estimation accuracy. Then, the 3D trajectory error of BiSAR is estimated by solving a series of linear equations of the trajectory error and the Doppler error with the least squares method, and a well-focused BiSAR image is produced by using the corrected 3D trajectories. Finally, simulation and experiment results are presented to demonstrate the effectiveness of the proposed method.

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Spatially Variable Phase Filtering Algorithm Based on Azimuth Wavenumber Regularization for Bistatic Spotlight SAR Imaging Under Complicated Motion

Cited by 2 publications

References 33 publications

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

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

An Estimation and Compensation Method for Motion Trajectory Error in Bistatic SAR

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