Extended Two-Step Focusing Approach for Squinted Spotlight SAR Imaging

An, Daoxiang; Huang, Xianglin; Jin, Tian; Zhou, Zhimin

doi:10.1109/tgrs.2011.2174460

Cited by 85 publications

(73 citation statements)

References 11 publications

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“…For the high-resolution case, this mismatch results in azimuth edge targets defocusing and the DOAF is very small. For example, it is only about 240m using the method in [10] with parameters in Table I. Thus, the full-scene in Fig.…”

Section: Azimuth Processing With Azimuth Spatial Variation Removingmentioning

confidence: 99%

“…To deal with the first issue, several methods have been proposed, such as the modified Stolt-based method for squinted spotlight mode [10], and the modified range migration method for squinted TOPS SAR [11]. However, these methods are not suitable for high-resolution sliding-spotlight data processing in squinted case.…”

Section: Introductionmentioning

confidence: 99%

“…However, these methods are not suitable for high-resolution sliding-spotlight data processing in squinted case. For the second issue, the subscene processing method [10] can be used to obtain high-quality full-scene image, but it will reduce processing efficiency in the high-resolution large-scene case. Another method is nonlinear chirp scaling (NLCS), which can equalize the targets' Doppler rates before azimuth compression by multiplying a cubic phase perturbation factor in azimuth-time domain [12][13].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Novel Imaging Algorithm for Focusing High-Resolution Spaceborne SAR Data in Squinted Sliding-Spotlight Mode

Chen¹,

Kuang

Yang

et al. 2016

IEEE Geosci. Remote Sensing Lett.

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Abstract-To process squinted sliding-spotlight synthetic aperture radar (SAR) data, the azimuth preprocessing step based on the linear range walk correction (LRWC) and de-rotation operations is implemented to eliminate the effect of two-dimensional (2-D) spectrum skew and azimuth spectral aliasing. However, two key issues arise from the azimuth preprocessing. Firstly, the traditional chirp scaling (CS) kernel is not suitable for data focusing because the property of 2-D spectrum is changed significantly; secondly, the spatial variation of the targets' Doppler rates along the azimuth direction due to the LRWC operation limits the depth-of-azimuth-focus (DOAF) seriously. In this letter, a modified accurate CS kernel is derived to realize range compensation. Then an azimuth spatial variation removing method based on the principle of nonlinear CS (NLCS) is proposed to equalize the Doppler rates of the targets located at the same range cell, which can extend the DOAF and improve processing efficiency. Finally, a novel imaging algorithm is proposed, with its effectiveness demonstrated by simulation results.Index Terms-Azimuth spatial variation removing, modified chirp scaling (CS) kernel, squinted sliding-spotlight, synthetic aperture radar (SAR).

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Section: Azimuth Processing With Azimuth Spatial Variation Removingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Novel Imaging Algorithm for Focusing High-Resolution Spaceborne SAR Data in Squinted Sliding-Spotlight Mode

Chen¹,

Kuang

Yang

et al. 2016

IEEE Geosci. Remote Sensing Lett.

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show abstract

“…The Doppler spectrum in a SAR scenario at a high squint angle becomes very oblique, demanding a higher pulse repetition frequency (PRF) and possibly resulting in a folded spectrum in the Dopplerfrequency domain [6][7][8]. The folded-spectrum problem can be solved by increasing the PRF [6,7], which is equivalent to reducing the azimuth sampling interval.…”

Section: Introductionmentioning

confidence: 99%

An Improved Range-Doppler Algorithm for Sar Imaging at High Squint Angles

Chen¹,

Kiang²

2017

PIER M

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Abstract-An improved range-Doppler algorithm (RDA) is proposed to reconstruct images from synthetic aperture radar (SAR) data received at high squint angles. At a higher squint angle, a larger synthetic aperture is required to receive sufficient amount of data for image reconstruction, and the range migration also becomes more serious, which demands more computational load and larger memory size. The proposed method can generate better SAR images with less computational load and memory than the conventional RDA, which is verified by simulations.

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“…The imaging algorithms for spotlight SAR include the polar format algorithm (PFA) [1,7,8], the range migration algorithm (RMA) [1,[9][10][11], the chirp scaling algorithm (CSA) [12], the two step focusing approach (TSFA) [13][14][15] and the frequency scaling algorithm (FSA) [16,17] and so on. In PFA, the echo signal is dechirped with a reference function whose reference range is the instantaneous range of the scene center, which can be viewed as dechirp operation both in the range direction and in the azimuth direction.…”

Section: Introductionmentioning

confidence: 99%

An Extended Frequency Scaling Algorithm for High Squint Spotlight Airborne Sar

Zuo¹,

Pi²,

Min³

2013

PIER

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Abstract-In high squint spotlight mode SAR, the coupling of the range and azimuth is very serious, which brings challenges to the imaging. In this paper, an extended frequency scaling algorithm is proposed, in which the range migration correction is divided into two steps. Firstly the range walk correction is implemented in 2D time domain. In the second step, the residual range migration is corrected by the frequency scaling and bulk shift operations. Though the second range compression does not consider the range space variance, the range compression is precise. In the azimuth compression, because of the range walk correction, the azimuth modulation frequency rate becomes dependent on the azimuth position. In order to equalize the azimuth modulation frequency rate, the azimuth nonlinear chirp scaling method is involved to remove the dependence. The simulation experiments verify the validity of the proposed algorithm. The comparison of the imaging quality among traditional frequency scaling algorithm, nonlinear frequency scaling algorithm and the proposed method indicates the proposed method is more suitable for the high squint spotlight SAR.

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Extended Two-Step Focusing Approach for Squinted Spotlight SAR Imaging

Cited by 85 publications

References 11 publications

A Novel Imaging Algorithm for Focusing High-Resolution Spaceborne SAR Data in Squinted Sliding-Spotlight Mode

A Novel Imaging Algorithm for Focusing High-Resolution Spaceborne SAR Data in Squinted Sliding-Spotlight Mode

An Improved Range-Doppler Algorithm for Sar Imaging at High Squint Angles

An Extended Frequency Scaling Algorithm for High Squint Spotlight Airborne Sar

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