Generalized Omega-K Algorithm for Geosynchronous SAR Image Formation

Hu, Bin; Jiang, Yicheng; Zhang, Shunsheng; Zhang, Yun; Yeo, Tat‐Soon

doi:10.1109/lgrs.2015.2470516

Cited by 25 publications

(35 citation statements)

References 8 publications

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“…To satisfy the SNR requirement, inclined orbit GEO SAR system needs a higher power and a larger antenna size [19]. It achieves the designed azimuth resolution by a relative shorter integration time and it is sensitive to ionosphere and cluster disturbances [20][21][22][23][24][25][26][27][28]. In contrast, the geostationary system has lower requirements of the power and the antenna size [20].…”

Section: Bandmentioning

confidence: 99%

Performance and Requirements of GEO SAR Systems in the Presence of Radio Frequency Interferences

Guarnieri

et al. 2018

Remote Sensing

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Geosynchronous Synthetic Aperture Radar (GEO SAR) is a possible next generation SAR system, which has the excellent performance of less than one-day revisit and hundreds of kilometres coverage. However, Radio Frequency Interference (RFI) is a serious problem, because the specified primary allocation frequencies are shared by the increasing number of microwave devices. More seriously, as the high orbit of GEO SAR makes the system have a very large imaging swath, the RFI signals all over the illuminated continent will interfere and deteriorate the GEO SAR signal. Aimed at the RFI impact in GEO SAR case, this paper focuses on the performance evaluation and the system design requirement of GEO SAR in the presence of RFI impact. Under the RFI impact, Signal-to-Interference-plus-Noise Ratio (SINR) and the required power are theoretically deduced both for the ground RFI and the bistatic scattering RFI cases. Based on the theoretical analysis, performance evaluations of the GEO SAR design examples in the presence of RFI are conducted. The results show that higher RFI intensity and lower working frequency will make the GEO SAR have a higher power requirement for compensating the RFI impact. Moreover, specular RFI bistatic scattering will give rise to the extremely serious impact on GEO SAR, which needs incredible power requirements for compensations. At last, real RFI signal behaviours and statistical analyses based on the SMOS satellite, Beidou-2 navigation satellite and Sentinel-1 A data have been given in the appendix.

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Section: Bandmentioning

confidence: 99%

Performance and Requirements of GEO SAR Systems in the Presence of Radio Frequency Interferences

Guarnieri

et al. 2018

Remote Sensing

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“…Therefore, the difference between the theoretical assumption and real orbit degrades the imaging quality in the azimuth direction. Aiming to solve this problem, a sequence of algorithms have been developed in order to cope with spaceborne spotlight SAR on a curved orbit, which describe the relative satellite-earth motion using Taylor expansion with azimuth time [11][12][13][14]. In the literature [11], a slant range model based on fourth-order Taylor expansion is firstly proposed and is implemented to process spaceborne spotlight SAR data on a curved orbit.…”

Section: Introductionmentioning

confidence: 99%

“…Subsequently, a method, which is named as generalized ωK, is proposed by combining multivariable Taylor expansion with the derivation of 2D spectrum in [16]. The generalized ωK presented in [13] is utilized to deal with geosynchronous spotlight SAR on a curved orbit. Consequently, the generalized ωK is extended to adapt for SAR data with squint angle in [14].…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, the generalized ωK is extended to adapt for SAR data with squint angle in [14]. Although, the algorithms presented in [13,14] perform satisfactorily in the case of geosynchronous spotlight SAR, the phase error induced by the first-order multivariable Taylor expansion cannot be neglected when resolution attains decimeter level. Apart from algorithms derived from the slant range model in [11], the singular value decomposition Stolt (SVDS) presented in [19] offers another approach for settling the problem caused by curved orbit.…”

Section: Introductionmentioning

confidence: 99%

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Focusing of Ultrahigh Resolution Spaceborne Spotlight SAR on Curved Orbit

Qian

Zhu

2019

Electronics

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Aiming to acquire ultrahigh resolution images, algorithms for spaceborne spotlight synthetic aperture radar (SAR) imaging typically confront challenges of curved orbit and azimuth spectral aliasing. In order to conquer these difficulties, a method is proposed in this paper to obtain ultrahigh resolution spaceborne SAR images on a curved orbit, which is composed of the modified RMA (Range Migration Algorithm) and the modified deramping-based approach. The modified RMA is developed to deal with the effect introduced by a curved orbit and the modified deramping-based approach is utilized to handle the problem of azimuth spectral aliasing. In the modified RMA, the polynomial expression of SAR two-dimensional spectrum on a curved orbit is derived with fourth-order azimuth phase history model and series reversion. Then, the singular value decomposition (SVD) is applied to decompose the expression of SAR two-dimensional spectrum numerically in order to acquire coordinates for Stolt interpolation in the scenario of curved orbit. In addition, the modified deramping-based approach is derived by introducing orbital state vectors in order to accommodate the situation of curved orbit in the proposed method. Experiments are implemented on point target simulation in order to verify the effectiveness of the presented method. In experiments, the range and azimuth resolution can achieve 0.15 m and 0.14 m, with focused scene size of 3 km by 3 km.

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“…It has a short revisit time of less than 24 h and extensive imaging coverage of more than 1000 km [4,5], which helps to realize the fast revisit and imaging of scenes of interest [6,7]. Therefore, the combination of GEO SAR and differential SAR interferometry (D-InSAR) can realize timely surface deformation detection, which has great advantages in the evaluation and forecast of natural disasters (earthquakes, landslides, volcano eruptions, etc.)…”

Section: Introductionmentioning

confidence: 99%

Impacts of Temporal-Spatial Variant Background Ionosphere on Repeat-Track GEO D-InSAR System

Dong

et al. 2016

Remote Sensing

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An L band geosynchronous synthetic aperture radar (GEO SAR) differential interferometry system (D-InSAR) will be obviously impacted by the background ionosphere, which will give rise to relative image shifts and decorrelations of the SAR interferometry (InSAR) pair, and induce the interferometric phase screen errors in interferograms. However, the background ionosphere varies within the long integration time (hundreds to thousands of seconds) and the extensive imaging scene (1000 km levels) of GEO SAR. As a result, the conventional temporal-spatial invariant background ionosphere model (i.e., frozen model) used in Low Earth Orbit (LEO) SAR is no longer valid. To address the issue, we firstly construct a temporal-spatial background ionosphere variation model, and then theoretically analyze its impacts, including relative image shifts and the decorrelation of the GEO InSAR pair, and the interferometric phase screen errors, on the repeat-track GEO D-InSAR processing. The related impacts highly depend on the background ionosphere parameters (constant total electron content (TEC) component, and the temporal first-order and the temporal second-order derivatives of TEC with respect to the azimuth time), signal bandwidth, and integration time. Finally, the background ionosphere data at Isla Guadalupe Island (29.02 • N, 118.27 • W) on 7-8 October 2013 is employed for validating the aforementioned analysis. Under the selected background ionosphere dataset, the temporal-spatial background ionosphere variation can give rise to a relative azimuth shift of dozens of meters at most, and even the complete decorrelation in the InSAR pair. Moreover, the produced interferometric phase screen error corresponds to a deformation measurement error of more than 0.2 m at most, even in a not severely impacted area.

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Generalized Omega-K Algorithm for Geosynchronous SAR Image Formation

Cited by 25 publications

References 8 publications

Performance and Requirements of GEO SAR Systems in the Presence of Radio Frequency Interferences

Performance and Requirements of GEO SAR Systems in the Presence of Radio Frequency Interferences

Focusing of Ultrahigh Resolution Spaceborne Spotlight SAR on Curved Orbit

Impacts of Temporal-Spatial Variant Background Ionosphere on Repeat-Track GEO D-InSAR System

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