Performance Analysis of L-Band Geosynchronous SAR Imaging in the Presence of Ionospheric Scintillation

Hu, Cheng; Li, Yuanhao; Dong, Xichao; Wang, Rui; Ao, Dongyang

doi:10.1109/tgrs.2016.2602939

Cited by 59 publications

(28 citation statements)

References 42 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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“…Step 2: Fine searching motion parameter for GRFT-based imaging Using GRFT to realize the moving ship target imaging with fine searching motion parameter, the radial velocity's searching interval is given by (25) in Section 3.3.2; the radial velocity's searching scope isv r_ f ∈ v r_r − ρ r /T Iv r_r + ρ r /T I ; and, the azimuth searching velocity is set asv a . The minimum entropy (26), which has obtained by Section 3.4, is used as criterion to determine whether the relocation requirement (|v r − v r | ≤ λ/2T I is shown in Section 3.3.1) is satisfied. When the entropy of GRFT response is minimum, the radial searched velocity isv r_ f .…”

Section: Procedures Of the Moving Ship Target Detection And Imagingmentioning

confidence: 99%

“…be observed within the range of every 1.5-2.5 h per day [14]. Thus, GEO SAR has great advantages in ship surveillance over vast ocean area.Currently, there are growing interests for GEO SAR, which are mainly concentrated on system design and mission planning [15][16][17][18][19][20][21], imaging algorithms [22][23][24][25], ionospheric effects and compensation [26][27][28], and deformation retrieval [29][30][31]. However, there are rarely related researches on detection and imaging of moving ships.Obviously, due to high time resolution and wide swath coverage, GEO SAR has great potential in monitoring moving ships.…”

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confidence: 99%

GRFT-Based Moving Ship Target Detection and Imaging in Geosynchronous SAR

et al. 2018

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Geosynchronous synthetic aperture radar (GEO SAR) has great potentials in ship surveillance due to its high time resolution and wide swath coverage. However, the remote slant range will result in a very low signal-to-noise ratio (SNR) of echoes that need to be enhanced by long-time coherent integration. The generalized Radon-Fourier transform (GRFT) can realize the coherent integration of moving target under long integration time by jointly parameter searching along range and velocity directions. Unfortunately, in GEO SAR, the very large slant range and long synthetic aperture will cause the curved synthetic aperture trajectory and non-negligible signal round-trip delay, leading to the failure of the traditional slant range and GRFT signal model for moving targets. This paper proposes an improved GRFT-based approach to realize the detection and imaging of moving ship targets in GEO SAR. Firstly, the accurate slant range for moving ship targets is constructed and the GRFT signal is redefined considering the curved trajectory and signal round-trip delay in GEO SAR. Then, GRFT responses to different motion parameters are analyzed. The procedures of moving ship targets detection and imaging in GEO SAR are presented through the detection with coarse-searched motion parameters in GRFT and the following imaging with fine-searched motion parameters based on minimum entropy. Finally, computer simulations verify the proposed GRFT-based method. be observed within the range of every 1.5-2.5 h per day [14]. Thus, GEO SAR has great advantages in ship surveillance over vast ocean area.Currently, there are growing interests for GEO SAR, which are mainly concentrated on system design and mission planning [15][16][17][18][19][20][21], imaging algorithms [22][23][24][25], ionospheric effects and compensation [26][27][28], and deformation retrieval [29][30][31]. However, there are rarely related researches on detection and imaging of moving ships.Obviously, due to high time resolution and wide swath coverage, GEO SAR has great potential in monitoring moving ships. However, the remote slant range of GEO SAR will result in a very low signal-to-noise ratio (SNR) of echoes. The defect of low SNR can be compensated for the static target through long time integration [32]. Unfortunately, the parameters of moving targets are unknown, leading to the failure of coherent integration and the resultantly SNR loss. Therefore, traditional detection and imaging methods for moving targets used in LEO SAR and airborne SAR are not suitable for GEO SAR.Moving targets detection and imaging can be divided into single-channel and multi-channel SAR schemes according to SAR system configuration. Because of the limitation of low SNR, multichannel configuration cannot be realized currently, as it is mainly designed for clutter suppression where ships have higher radar cross section (RCS) against the surrounding sea background (in general, ships has higher backscattering energy as the metallic materials and corner reflection structures [33,34]). Therefore, mo...

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“…In the single baseline case, an interesting result can be obtained by manipulating (5). If the Z axis is defined in the same direction as the baseline, the following expression can be derived:…”

Section: Far-field Approximation Modelmentioning

confidence: 99%

“…An accurate image of the scene after SAR processing can be obtained if the range history of every point of the scene is accurately known. This fact necessitates high-precision orbit modeling (with accuracies in the order of magnitude of λ), the use of suitable techniques for atmospheric phase screen compensation [4], and the study and correction of ionospheric effects [5], especially at large wavelengths such as the L band. Such orbital determination requirements are well beyond the usual systems used to manage repositioning of satellites in geostationary orbits.…”

Section: Introduction: the Geosar Missionmentioning

confidence: 99%