Prediction, Detection, and Correction of Faraday Rotation in Full-Polarimetric L-Band SAR Data

Meyer, Franz J.; Nicoll, J.

doi:10.1109/tgrs.2008.2003002

Cited by 119 publications

(98 citation statements)

References 19 publications

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“…Assuming δ 1 = δ 2 = δ 3 = δ 4 = δ for convenience [2,4,32], the scattering matrix of Equation (2) [2,5]. We can see that in area of Changbai, Ω F performs the best and can be applied in CIT reconstructions.…”

Section: Cit Reconstructions Under the Condition Of Crosstalkmentioning

confidence: 98%

“…where the channel imbalances in the receiver and transmitter are assumed to be identical (i.e., f 1 = f 2 = f ) to simplify the analysis [2,4,32]. The effects of channel phase imbalance, i.e., f = 1 × exp(iφ), on the FR estimators are first evaluated under typical values [2,5].…”

Section: Cit Reconstructions Under the Condition Of Channel Imbalancementioning

confidence: 99%

Section: Cit Reconstructions Under the Combination Of System Errorsmentioning

confidence: 99%

“…Thus, in order to make a practical value for our CIT technique, the system errors (i.e., noise, channel imbalance and crosstalk) are all considered in this subsection. According to the calibration accuracy of the PALSAR system [32], in simulations, we assume SNR = 15 dB , channel phase imbalance φ is 2 • , channel amplitude imbalance | f | is 0.5 dB, and crosstalk δ is −35 dB. Table 13 shows the performances of FR estimators under the condition of joint errors, we can see that for the area of Changbai, Ω C will be the preferred estimator while Ω BB performs the best for the area of Qingdao.…”

Section: Cit Reconstructions Under the Combination Of System Errorsmentioning

confidence: 99%

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Ionospheric Reconstructions Using Faraday Rotation in Spaceborne Polarimetric SAR Data

et al. 2017

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Abstract:It is well known that the Faraday rotation (FR) is obviously embedded in spaceborne polarimetric synthetic aperture radar (PolSAR) data at L-band and lower frequencies. By model inversion, some widely used FR angle estimators have been proposed for compensation and provide a new field in high-resolution ionospheric soundings. However, as an integrated product of electron density and the parallel component of the magnetic field, FR angle measurements/observations demonstrate the ability to characterize horizontal ionosphere. In order to make a general study of ionospheric structure, this paper reconstructs the electron density distribution based on a modified two-dimensional computerized ionospheric tomography (CIT) technique, where the FR angles, rather than the total electron content (TEC), are regarded as the input. By using the full-pol (full polarimetric) data of Phase Array L-band Synthetic Aperture Radar (PALSAR) on board Advanced Land Observing Satellite (ALOS), International Reference Ionosphere (IRI) and International Geomagnetic Reference Field (IGRF) models, numerical simulations corresponding to different FR estimators and SAR scenes are made to validate the proposed technique. In simulations, the imaging of kilometer-scale ionospheric disturbances, a spatial scale that is rarely detectable by CIT using GPS, is presented. In addition, the ionospheric reconstruction using SAR polarimetric information does not require strong point targets within a SAR scene, which is necessary for CIT using SAR imaging information. Finally, the effects of system errors including noise, channel imbalance and crosstalk on the reconstruction results are also analyzed to show the applicability of CIT based on spaceborne full-pol SAR data.

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Section: Cit Reconstructions Under the Condition Of Crosstalkmentioning

confidence: 98%

Section: Cit Reconstructions Under the Condition Of Channel Imbalancementioning

confidence: 99%

Section: Cit Reconstructions Under the Combination Of System Errorsmentioning

confidence: 99%

Section: Cit Reconstructions Under the Combination Of System Errorsmentioning

confidence: 99%

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Ionospheric Reconstructions Using Faraday Rotation in Spaceborne Polarimetric SAR Data

et al. 2017

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“…A series of studies on the ionospheric effects on SAR and InSAR have been published since 1960s, including Faraday Rotation (FR) [9,10], phase advance [11], SAR resolution, and image shift. But, for the SAR interferometry, it has been demonstrated that the most significant effect was the azimuth streak [12].…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of Azimuth Offset Method for Mitigating the Ionospheric Effect on SAR Interferometry

Zhu

Zhang

et al. 2017

Journal of Sensors

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Synthetic aperture radar (SAR) signals interact with the ionosphere layer when they propagate through the atmosphere, leading to the phase delay error for SAR interferometry (InSAR). To mitigate this error for SAR interferometry, azimuth offset method is proposed. However, the performance of it has not been fully investigated. In this situation, this study makes a comprehensive performance analysis of azimuth offset method through processing the simulated and real SAR data. The experimental result indicates that this method can effectively mitigate the ionospheric phase delay error, where the standard deviation of phase difference after correction (2.6 rad.) decreased by almost 2 times, compared to those before correction (5.3 rad.) for the real SAR data. However, it is also found that the method is affected by the random noise, which may induce the improper estimation of integral constants and consequently affect the ionospheric correction. Moreover, the severe deformation signals in the interferogram may lead to the estimation error of integral constants and scaling factor. Therefore, it should mask out the deformation signals when using the azimuth offsets method to correct the ionospheric error. This study may provide useful information when using azimuth offset method to mitigate the ionospheric phase delay error on InSAR.

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TEC retrieval from spaceborne SAR data and its applications

Wang

Min

et al. 2014

JGR Space Physics

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It is well known that the spaceborne synthetic aperture radar (SAR) at VHF-UHF band can be seriously affected by the ionosphere. Thus, the geophysical information of the ionosphere will be embedded in the low-frequency SAR echoes after they transverse the ionosphere. Correspondingly, the total electron content (TEC), a typical ionospheric information parameter, can be retrieved from the spaceborne SAR data. However, the existing dual-band techniques for TEC retrieval usually do not include consideration of multiple scattering effects caused by turbulent ionosphere, which plays an important role in the total path delay of signal under the strong fluctuation regimes. The result of TEC retrieval is therefore inaccurate and not applicable. Aiming at this issue, first, this paper analyzes the effects of regular background and the irregularity of electron density on SAR at L-band, and the theoretical formulation is given. Then, a triband path delay technique of TEC retrieval based on the SAR data is proposed. By using three path delays corresponding to three specific frequencies within the signal bandwidth, this technique can remove the errors of multiple scattering due to the irregularity, and a high accuracy resolution of TEC value therefore can be obtained. Meanwhile, the sensitivity of this technique is analyzed. Finally, compared with traditional dual-band technique, the numerical simulations show that the correction of SAR imaging based on triband technique is improved significantly. In addition, the resolution of reconstruction imaging using computerized ionospheric tomography performs significantly better based on the triband technique.

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Prediction, Detection, and Correction of Faraday Rotation in Full-Polarimetric L-Band SAR Data

Cited by 119 publications

References 19 publications

Ionospheric Reconstructions Using Faraday Rotation in Spaceborne Polarimetric SAR Data

Ionospheric Reconstructions Using Faraday Rotation in Spaceborne Polarimetric SAR Data

Performance Evaluation of Azimuth Offset Method for Mitigating the Ionospheric Effect on SAR Interferometry

TEC retrieval from spaceborne SAR data and its applications

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