Cubic Phase Distortion and Irregular Degradation on SAR Imaging Due to the Ionosphere

Wang, Cheng; Zhang, Min; Xu, Zhengwen; Chen, Chun; Guo, Lixin

doi:10.1109/tgrs.2014.2376957

Cited by 21 publications

(14 citation statements)

References 35 publications

(37 reference statements)

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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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“…Hence, the radio signal is inevitably affected by the ionosphere during the propagation, the extent depending on the radar frequency [7,8]. The ultra-high frequency (UHF), particularly, experiences more adverse effects from the ionosphere; and thus, the imaging performance of the spaceborne SAR operating at UHF is degraded due to the ionospheric effects [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Therefore, it is important to understand those potential effects on the P-band spaceborne SAR imaging before its data can be better used.…”

Section: Introductionmentioning

confidence: 99%

“…More specifically, the FR alters the amplitude and phase balance in the polarimetric channels, which subsequently causes attenuation to the radio signal and further changes scattering properties of the surface compared to the case where the radio signal is not affected by the FR [7,[9][10][11]. The background ionospheric effects could induce phase shift, and bring about imaging distortion in lines of image shift and defocusing phenomenon [22][23][24][25][26][27]. The ionospheric scintillation would lead to fluctuations in amplitude and phase of the signal, and thus affect the imaging focusing of the spaceborne SAR system [14][15][16][17]24].…”

Section: Introductionmentioning

confidence: 99%

“…Until now, the background ionospheric effects have been analyzed in the context of the ionospheric freezing model, in which the ionospheric Total Electron Content (TEC) is regarded as time-invariant during the synthetic aperture time [13,[22][23][24]28]. However, some studies concerning the temporally varying background ionospheric effects, such as in [25][26][27], showed that effect of the temporally varying component of background ionosphere is in a negative correlation to the center frequency.…”

Section: Introductionmentioning

confidence: 99%

“…At present, the background ionospheric effects in terms of geometric distortion and image defocusing on the P-band spaceborne SAR are detailed analyzed in [7,11,13,[22][23][24]. However, in those works, there is little concern about effects of spatiotemporally varying part of the background ionosphere.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Study of the Spatiotemporally-Varying Background Ionospheric Effects on P-Band Satellite SAR Imaging

Chen

2020

IEEE Access

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At the relatively low frequency of the P-band spaceborne SAR, the background ionosphere is no longer treated as time-invariant, together with the spatial variation in the background ionosphere, and complicates the spaceborne SAR imaging. In this paper, we systematically quantify the effects of the spatiotemporally varying background ionosphere on the imaging performance of the P-band spaceborne SAR. The signal model for a P-band spaceborne SAR is established in accordance with the range history taking account of the Earth's rotation, based on which the 2-dimensional (2-D) signal frequency spectrum under the influence of spatiotemporally varying background ionosphere is derived. Then, the geometric distortion and defocusing phenomenon in the range and azimuth directions are quantitatively evaluated. It is found that the range shift is mainly determined by the constant component of the background ionosphere, and the contribution from the spatiotemporally varying components of the background ionosphere is nonnegligible. In contrast, the azimuth shift has no dependency on the constant part of the background ionosphere, but both the spatially varying and temporally varying components of the background ionosphere could give rise to considerable azimuth shifts. Regarding the focusing quality, it is seldom impaired by the background ionosphere for the P-band spaceborne SAR with a coarse spatial resolution on a decameter scale. However, the high spatial resolution makes it difficult to maintain good focusing qualities, especially at the high solar activity. Finally, numerical simulations in terms of the single-point target responses confirm the theoretical analysis; simulations of responses of array-point targets, together with 2-D image shifts along the satellite's track, show the disparity of background ionosphere can further affect the imaging performance of the P-band spaceborne SAR. In this respect, effects of spatiotemporally varying background ionosphere deserve special care in the signal processing of a P-band spaceborne SAR. INDEX TERMS P-band spaceborne SAR, spatiotemporally varying, background ionospheric effects, geometric distortion, focusing quality, disparity of background ionosphere.

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Ionospheric Experiment Validation and Compensation

Ding

et al. 2018

Geosynchronous SAR: System and Signal Processing

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Cubic Phase Distortion and Irregular Degradation on SAR Imaging Due to the Ionosphere

Cited by 21 publications

References 35 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

Numerical Study of the Spatiotemporally-Varying Background Ionospheric Effects on P-Band Satellite SAR Imaging

Ionospheric Experiment Validation and Compensation

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