Sliding spotlight SAR processing for TerraSAR-X using a new formulation of the extended chirp scaling algorithm

Mittermayer, Josef; Lord, R.T.; Börner, Elke

doi:10.1109/igarss.2003.1294144

Cited by 101 publications

(63 citation statements)

References 4 publications

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“…Fortunately, the spaceborne TOPS mode usually has a limited maximum azimuth beam steering capability, and existing stripmap focusing processors [16][17][18][19][20][21][22][23][24] can implement SAR data focusing well in this case. In addition to taking conventional stripmap imaging processors, problems of the aliased Doppler spectra and the azimuth output back folding in the SAR image should be resolved.…”

Section: Modified Ecs Algorithmmentioning

confidence: 99%

“…These operations make SAR imaging algorithms less efficient and require more computer memory. Fortunately, the SAR raw data with azimuth varying Doppler centroid can be focused via the efficient spectrum analysis (SPECAN) operation [17,19,20]. According to special properties of the TOPS raw data, an efficient focusing algorithm, which takes advantage of the use of subaperture, and SPECAN, is proposed.…”

Section: Introductionmentioning

confidence: 99%

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An Efficient Imaging Approach for Tops Sar Data Focusing Based on Scaled Fourier Transform

Huang¹,

Xu²

2013

PIER B

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Abstract-This paper presents an efficient imaging algorithm for Terrain Observation by Progressive Scans (TOPS) mode SAR raw data focusing. First, the use of subaperture is adopted to overcome the aliased Doppler spectra due to progress azimuth beam scanning. Afterwards, range compression and range cell migration correction (RCMC) are individually implemented in each azimuth block with its individual Doppler centroid. After azimuth subaperture signal recombination, a new Doppler centroid varying rate is introduced to avoid the reconstructed Doppler spectra wrapping. Moreover, azimuth varying beam center time is removed by azimuth frequency scaling before the final azimuth spectrum analysis (SPECAN) step. Finally, the conventional Fourier transform (FT) is replaced by the scaled Fourier transform (SCFT) step to obtain the uniform azimuth space sampling interval. Since the proposed imaging algorithm is without any interpolations and azimuth data extension, it is highly efficient. Simulation results on point targets validate the proposed algorithm.

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Section: Modified Ecs Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Efficient Imaging Approach for Tops Sar Data Focusing Based on Scaled Fourier Transform

Huang¹,

Xu²

2013

PIER B

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“…More recently, intermediate modes have been developed, referred to as sliding spotlight SAR or hybrid stripmap-spotlight SAR [1,2]. These modes explore the trade-off between stripmap and spotlight mode to generate SAR images with improved azimuth resolution compared to the former and improved ground coverage compared to the latter.…”

Section: Introductionmentioning

confidence: 99%

Synthetic aperture imaging using a randomly steered spotlight

Liu

Boufounos

2013

2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS

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In this paper, we develop a new approach to synthetic aperture imaging inspired by recently developed compressive sensing (CS) methods. Our approach modifies the beam steering pattern of conventional sliding spotlight-mode systems and randomizes it such that with each pulse the beam illuminates a different, randomly chosen, part of the imaged area. The randomization allows the acquisition of the area of interest with a significantly larger effective aperture compared to the conventional sliding spotlight mode and, therefore, with significantly larger resolution. The reconstruction estimates the signal using a model that combines a sparse and a dense component. This model captures the structure of SAR images better than conventional sparse models, typically used in CS, and provides superior reconstruction performance. Our experimental results demonstrate that the proposed randomly steered spotlight array can improve imaging resolution, as measured by the reconstruction SNR and the phase error, without compromising the covered area size. International Geoscience and Remote Sensing Symposium (IGARSS)This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Mitsubishi Electric Research Labs, {liudh,petrosb}@merl.com ABSTRACT In this paper, we develop a new approach to synthetic aperture imaging inspired by recently developed compressive sensing (CS) methods. Our approach modifies the beam steering pattern of conventional sliding spotlight-mode systems and randomizes it such that with each pulse the beam illuminates a different, randomly chosen, part of the imaged area. The randomization allows the acquisition of the area of interest with a significantly larger effective aperture compared to the conventional sliding spotlight mode and, therefore, with significantly larger resolution. The reconstruction estimates the signal using a model that combines a sparse and a dense component. This model captures the structure of SAR images better than conventional sparse models, typically used in CS, and provides superior reconstruction performance. Our experimental results demonstrate that the proposed randomly steered spotlight array can improve imaging resolution, as measured by the reconstruction SNR and the phase error, without compromising the covered area size.

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“…This phenomenon makes it impossible to apply the frequency domain imaging algorithms for stripmap mode to process spotlight data directly. Different kinds of solutions have been developed to overcome the spectrum folding problem: the azimuth oversampling technique Prati and Rocca, 1992;Belcher and Baker, 1996], the sub-aperture technique [Mittermayer et al, 2003], and the derampingbased technique [Lanari et al, 1993. After azimuth spectrum unfolding, traditional stripmap mode imaging algorithms can be used to obtain focused images.…”

Section: Introductionmentioning

confidence: 99%

Extension of Wavenumber Domain Focusing for spotlight COSMO-SkyMed SAR Data

Lorusso

Nicoletti

Gallipoli

et al. 2015

European Journal of Remote Sensing

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In this work we describe a method to handle curved orbits in wavenumber domain focusing algorithm for high-resolution SAR data acquired by Low Earth Orbit satellites using spotlight mode. The standard wavenumber domain focusing algorithm make assumptions that start to be invalid when applied to high-resolution spotlight SAR data acquired in spaceborne low Earth orbit (LEO) configurations. The assumption of a hyperbolic range history is no longer accurate for sub-metric spatial resolutions due to the satellite curved orbit. The proposed method is used to estimate the satellite velocity and closest-approach range distance of the rectified effective orbit which minimizes the phase errors over the whole scene coverage. This allows to use all frequency domain focusing kernels developed to focus SAR images acquired with a stripmap mode. We use this method with the ω-k algorithm, and its approximation Fast ω-k (Fω-k), demonstrating its effectiveness to focus COSMO-SkyMed (CSK) SAR images obtaining, respectively, sub-metric and metric azimuth spatial resolution.

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Sliding spotlight SAR processing for TerraSAR-X using a new formulation of the extended chirp scaling algorithm

Cited by 101 publications

References 4 publications

An Efficient Imaging Approach for Tops Sar Data Focusing Based on Scaled Fourier Transform

An Efficient Imaging Approach for Tops Sar Data Focusing Based on Scaled Fourier Transform

Synthetic aperture imaging using a randomly steered spotlight

Extension of Wavenumber Domain Focusing for spotlight COSMO-SkyMed SAR Data

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