Nonambiguous Image Formation for Low-Earth-Orbit SAR With Geosynchronous Illumination Based on Multireceiving and CAMP

An, Hongyang; Wu, Junjie; Teh, Kah Chan; Sun, Zhichao; Yang, Jianyu

doi:10.1109/tgrs.2020.2992744

Cited by 12 publications

(5 citation statements)

References 44 publications

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“…To facilitate accurate imaging in the case of GEO-LEO bistatic SAR, improved propagation delay models and their corresponding range models have been established. The GEO-LEO bistatic SAR imaging problem was modeled as the recovery of low-rank matrices [21,22], which effectively reduced the number of necessary receiving channels. However, these methodologies are unsuitable for the BP algorithm.…”

Section: Introductionmentioning

confidence: 99%

An Accurate and Efficient BP Algorithm Based on Precise Slant Range Model and Rapid Range History Construction Method for GEO SAR

Wu,

Huang,

Zhang

et al. 2023

Remote Sensing

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The Geosynchronous Satellite Synthetic Aperture Radar (GEO SAR) operates at a high orbital altitude, resulting in an extended imaging time and substantial variations in slant range. Additionally, the GEO SAR satellite orbit experiences a bending effect, and the target’s movement, caused by the Earth’s rotation, is influenced by the Earth’s curvature. The back-projection (BP) algorithm has been proven to be a highly effective technique for precise imaging with GEO SAR by processing these specific echo signals. However, this approach necessitates considerable computational resources. Existing BP algorithms, such as the fast BP algorithm, do not consider the “Stop-and-Go” error present in GEO SAR. Consequently, we developed a Precise Slant Range Model that considers the motion of both the satellite and targets. The model incorporates velocity and acceleration factors to accurately represent the signal transmission from transmission to reception. Additionally, we propose a Rapid Range History Construction Method to lessen the computational burden of generating the three-dimensional range history array. By utilizing the Precise Slant Range Model and the Rapid Range History Construction Method, and employing parallel processing through aperture segmentation, we propose an Accurate and Efficient BP imaging algorithm suitable for GEO SAR applications. To validate its effectiveness, simulations were conducted using the parameters of a GEO SAR system. The results indicated that the proposed algorithm enhances the imaging quality of GEO SAR, reduces the processing time, and achieves high-precision rapid imaging, thereby improving operational efficiency.

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Section: Introductionmentioning

confidence: 99%

An Accurate and Efficient BP Algorithm Based on Precise Slant Range Model and Rapid Range History Construction Method for GEO SAR

Wu,

Huang,

Zhang

et al. 2023

Remote Sensing

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“…Furthermore, the airborne multichannel receiver can achieve different bistatic configurations for various applications without the constraints of a fixed orbit [6]. Most studies on GEO SA-BSAR are focused on the imaging of a stationary scene, including bistatic configuration design [7], resolution analysis [8][9][10], and imaging algorithms [11][12][13][14][15]. Various imaging modes, such as side-looking, squint-looking, and forwards-looking, were proved to be promising in recent research [8].…”

Section: Introductionmentioning

confidence: 99%

A Long-Time Coherent Integration STAP for GEO Spaceborne-Airborne Bistatic SAR

et al. 2022

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A geosynchronous spaceborne-airborne bistatic synthetic aperture radar (GEO SA-BSAR) system is an important technique to achieve long-time moving target monitoring over a wide area. However, due to special bistatic configuration of GEO SA-BSAR, two major challenges, i.e., severe range migration and space-variant Doppler parameters for moving targets, hinder the moving target indication (MTI) processing. Traditional SAR MTI methods, which do not take the challenges into consideration, will defocus the moving targets, leading to a loss of the signal-to-noise ratio (SNR). To focus moving targets and estimate motion parameters accurately, long-time coherent integration space-time adaptive processing (LTCI-STAP) is proposed for GEO SA-BSAR MTI in this paper. First, a modified adaptive spatial filtering based on the bistatic signal model is performed to suppress the clutter. Then, an LTCI filter bank is constructed to achieve range migration correction and moving target focusing, which yields the optimal output signal and filtering parameters. Finally, constant false alarm rate (CFAR) detection is carried out to determine the targets, and the space-variant Doppler parameters, solved from the filtering parameters, are used for estimating moving target positions and velocities. Simulations verify the effectiveness of our method.

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“…According to the Nyquist sampling theorem, the sampling rate of ADC in the SAR receiver should be more than 7 gigabit samples per second (GSPS) for the radar signal with the bandwidth of 3.5 GHz, which brings great challenges to ADC sampling devices and greatly increases the hardware cost. At present, in addition to using ultra-high-speed ADC directly, a series of methods to sample wideband signals has been proposed [15][16][17][18], which can be divided into the following three: Firstly, the de-chirp technology is able to convert wideband echoes into narrowband echoes, reducing the sampling rate of ADC [15]. However, the detection distance of de-chirp method is limited, and difficult to change.…”

Section: Introductionmentioning

confidence: 99%

“…However, the detection distance of de-chirp method is limited, and difficult to change. Thus, it is not suitable for high-resolution imaging of space targets at any distance; Secondly, the multi-channel receiving and stitching method in frequency domain is used to receive wideband signals, which utilizes multiple receiving channels to divide wideband echoes into multiple narrowband signals [16]. This method is complicated in hardware and stitching algorithms, so it is difficult to apply to a real-time space-borne SAR system.…”

Section: Introductionmentioning

confidence: 99%

A Novel Space-Borne High-Resolution SAR System with the Non-Uniform Hybrid Sampling Technology for Space Targets Imaging

Xia¹,

Jin²,

Yue³

et al. 2022

Applied Sciences

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In order to reduce the complexity of the receiving system for wideband signals, a novel space-borne high-resolution synthetic aperture radar (SAR) system with the non-uniform hybrid sampling technology is proposed in this paper. The non-uniform hybrid sampling technology is firstly applied in the SAR imaging system for the detection of space targets. The non-uniform hybrid sampling technology is able to optimize the transmitted and receiving timing of SAR signals, reducing the requirement of the sampling rate of the analog-to-digital converter (ADC) for the reception of the wideband echoes from space targets. Meanwhile, according to the oversampling requirement of SAR imaging in the azimuth direction, a theoretical model of non-uniform hybrid sampling parameters and relative velocity between the SAR system and the space targets is established. A series of simulation experiments with different targets and different non-uniform hybrid parameters are performed, and an X-band SAR imaging experimental system is constructed to verify the effectiveness of the proposed non-uniform hybrid sampling technology. The experimental results show that the imaging resolution is better than 8 cm. When the non-uniform hybrid sampling interval is 15 us, the imaging quality is consistent with imaging results of the Nyquist real-time sampling, and it is easier to implement in the high-resolution imaging for space targets.

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Nonambiguous Image Formation for Low-Earth-Orbit SAR With Geosynchronous Illumination Based on Multireceiving and CAMP

Cited by 12 publications

References 44 publications

An Accurate and Efficient BP Algorithm Based on Precise Slant Range Model and Rapid Range History Construction Method for GEO SAR

An Accurate and Efficient BP Algorithm Based on Precise Slant Range Model and Rapid Range History Construction Method for GEO SAR

A Long-Time Coherent Integration STAP for GEO Spaceborne-Airborne Bistatic SAR

A Novel Space-Borne High-Resolution SAR System with the Non-Uniform Hybrid Sampling Technology for Space Targets Imaging

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