Extended Nonlinear Chirp Scaling Algorithm for High-Resolution Highly Squint SAR Data Focusing

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

doi:10.1109/tgrs.2012.2183606

Cited by 147 publications

(120 citation statements)

References 19 publications

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“…An azimuth preprocessing step is implemented before focusing the data. First, the LRCM is corrected using the LRWC factor ( ) [13]. Then, the error caused by the curved orbit [9] is corrected using the filter ( ) …”

Section: R T R T R V T T Rv T T R T J Lgmentioning

confidence: 99%

“…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]. However, it is only suitable for processing squinted stripmap or squinted spotlight data.…”

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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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: R T R T R V T T Rv T T R T J Lgmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…Traditional range cell migration correction (RCMC) methods [23][24][25] operated in range frequency and azimuth time domains all use correction factor multiplication to remove the linear component of RCM. However, the linear RCMC factor is constructed by using the linear RCM of the reference target, and the spatial variance of linear RCM is neglected.…”

Section: Introductionmentioning

confidence: 99%

“…However, this algorithm can only deal with the spatial variance of Doppler frequency modulation rate. In some recent publications on highly squint monostatic SAR data focusing [24,25], an extended azimuth nonlinear chirp scaling algorithm (ENLCS) has been proposed. The ENLCS can simultaneously equalize the Doppler FM rate and third-order coefficient.…”

Section: Introductionmentioning

confidence: 99%

Focusing Translational Variant Bistatic Forward-Looking SAR Using Keystone Transform and Extended Nonlinear Chirp Scaling

Sun

et al. 2016

Remote Sensing

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Bistatic Synthetic Aperture Radar (SAR) has attracted increasing attention in recent years due to its unique advantages, such as the ability of forward-looking imaging. In translational variant bistatic forward-looking SAR (TV-BFSAR), it is difficult to get a well focused image due to large range cell migration (RCM) and 2-D variation of both Doppler characteristics and RCM. In this paper, an extended azimuth nonlinear chirp scaling (NLCS) algorithm is proposed to deal with these problems. Firstly, Keystone Transform (KT) is introduced to remove the spatial-variant linear RCM, which is of great significance in TV-BFSAR. Secondly, a correction factor is multiplied to the signal in range frequency domain to compensate for the residual RCM. At last, a fourth-order filtering together with azimuth NLCS is performed in every range gate to equalize both the azimuth-variant Doppler centroid and frequency modulation rate based on the azimuth numerical fitting. The proposed method is verified by simulation and real data processing. Multiple targets are generated and focused by the method, of which the peak sidelobe ratio (PSLR) is around −13 dB and integrated sidelobe ratio (ISLR) is around −10 dB. The method is accurate and can achieve high-resolution focusing for TV-BFSAR data.

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“…Since synthetic aperture radar (SAR) has the characteristics of imaging an interesting area with high resolution in all weather conditions, it moves radar technology from crude detection and estimation to fine resolution imaging and feature extraction [1][2][3][4][5]. Nowadays, it has become an important detecting tool in the military reconnaissance and civil remote sensing fields and has been widely used on airborne or missile-borne platforms.…”

Section: Introductionmentioning

confidence: 99%

Forward-Looking Imaging of Scanning Phased Array Radar Based on the Compressed Sensing

Wen¹,

Kuang²,

Hu³

et al. 2013

PIER

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Abstract-In this paper, a novel forward-looking imaging method based on the compressed sensing is proposed for scanning phased array radar (PAR) in order to improve the azimuth resolution. Firstly, the echo of targets is modeled according to the principle of PAR. Then, it is analyzed why some of the former methods as multi-channel deconvolution are ineffective based on the signal model. Using a widely accepted assumption that dominant scatterers in an interesting area are sparse or compressible, an imaging algorithm based on the compressed sensing is proposed and investigated. This method obtains its high range resolution by transmitting and compressing chirp pulse signal, and improves its azimuth resolution by utilizing the compressed sensing technique. The effectiveness of the proposed method is illustrated and analyzed with simulations data.

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Extended Nonlinear Chirp Scaling Algorithm for High-Resolution Highly Squint SAR Data Focusing

Cited by 147 publications

References 19 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

Focusing Translational Variant Bistatic Forward-Looking SAR Using Keystone Transform and Extended Nonlinear Chirp Scaling

Forward-Looking Imaging of Scanning Phased Array Radar Based on the Compressed Sensing

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