Focusing High-Resolution High Forward-Looking Bistatic SAR With Nonequal Platform Velocities Based on Keystone Transform and Modified Nonlinear Chirp Scaling Algorithm

Abstract The hyperbolic range equation model (HREM) and equivalent squint range model (ESRM) are applied in traditional chirp scaling algorithm (CSA). However, these range models cannot describe the satellite range history in the high-resolution case accurately because of the long azimuth integration time. The non-negligible phase error caused by this will lead the targets distort. In this paper, a modified chirp scaling algorithm (MCSA) is proposed by introducing a novel high-precision range model. A more accurate signal spectrum is calculated through it. Then, the modified chirp scaling factor, range compression filter, range cell migration correction (RCMC) filter and azimuth compression filter can be derived based on this signal spectrum, and the focused target obtained at last. Finally, the experimental results, to validate the proposed algorithm, adopted by the sliding spotlight synthetic aperture radar (SAR) simulation are provided.

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An MIMO Sonar Array for High-resolution 3D Forward-looking Imaging

OCEANS 2019 - Marseille ◽

10.1109/oceanse.2019.8867062 ◽

2019 ◽

Author(s):

Xionghou LIU ◽

Chi ZHANG ◽

Hongyu CHEN ◽

Chao SUN ◽

Yixin YANG ◽

...

Keyword(s):

High Resolution ◽

Forward Looking

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An Improved Generalized Chirp Scaling Algorithm Based on Lagrange Inversion Theorem for High-Resolution Low Frequency Synthetic Aperture Radar Imaging

Remote Sensing ◽

10.3390/rs11161874 ◽

2019 ◽

Vol 11 (16) ◽

pp. 1874 ◽

Cited By ~ 1

Author(s):

Xing Chen ◽

Tianzhu Yi ◽

Feng He ◽

Zhihua He ◽

Zhen Dong

Keyword(s):

High Resolution ◽

Stationary Phase ◽

Low Frequency ◽

Synthetic Aperture ◽

Phase Coupling ◽

Lagrange Inversion ◽

Inversion Theorem ◽

Coupling Phase ◽

Large Bandwidth ◽

Chirp Scaling Algorithm

The high-resolution low frequency synthetic aperture radar (SAR) has serious range-azimuth phase coupling due to the large bandwidth and long integration time. High-resolution SAR processing methods are necessary for focusing the raw data of such radar. The generalized chirp scaling algorithm (GCSA) is generally accepted as an attractive solution to focus SAR systems with low frequency, large bandwidth and wide beam bandwidth. However, as the bandwidth and/or beamwidth increase, the serious phase coupling limits the performance of the current GCSA and degrades the imaging quality. The degradation is mainly caused by two reasons: the residual high-order coupling phase and the non-negligible error introduced by the linear approximation of stationary phase point using the principle of stationary phase (POSP). According to the characteristics of a high-resolution low frequency SAR signal, this paper firstly presents a principle to determine the required order of range frequency. After compensating for the range-independent coupling phase above 3rd order, an improved GCSA based on Lagrange inversion theorem is analytically derived. The Lagrange inversion enables the high-order range-dependent coupling phase to be accurately compensated. Imaging results of P- and L-band SAR data demonstrate the excellent performance of the proposed algorithm compared to the existing GCSA. The image quality and focusing depth in range dimension are greatly improved. The improved method provides the possibility to efficiently process high-resolution low frequency SAR data with wide swath.

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