A new approach of TEC retrieval from the space-borne SAR
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摘要: 由于星载合成孔径雷达(SAR)系统工作于电离层之上,其信号不可避免地将受到电离层的影响. 背景电离层以及电离层电子密度不规则体多重散射效应可引起距离向图像质量的下降, 在强起伏情况下, 多重散射效应对信号的延迟影响不可忽略. 针对此问题, 本文提出了一种基于SAR回波信号的三频相位自适应TEC反演新方法, 利用反演的结果对电离层的影响进行校正. 给出了校正前后的点目标成像仿真, 结果显示此方法充分考虑了多重散射效应引起的TEC估计误差, 可以有效地补偿电离层对距离向成像的影响, 提高了距离向点目标图像质量.Abstract: Due to the background ionosphere and irregularities in the electron density of the ionosphere, the space-borne synthetic aperture radar (SAR) imaging at low-frequency is affected by it inevitably. From the simulations, it can be seen that under the strong fluctuation regimes, the path delay of multiple scattering plays an important role in the total path delay of SAR signals. Aiming at this problem, a tri-band phase autofocus method of TEC retrieval based on the SAR echo is proposed, which compensates the effects of the ionosphere on SAR imaging. Simulation results show that when this method is used under strong fluctuations, both the image quality in range and the precision of SAR calibration are generally increased after compensation.
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[1] Bamler R, Eineder M. 2005. Accuracy of differential shift estimation by correlation and split-bandwidth interferometry for wideband and delta-k SAR systems. IEEE Geoscience and Remote Sensing Letters, 2(2): 151-155.
[2] Elachi C E, Roth L E, Schaber G G. 1984. Spaceborne radar subsurface imaging in hyperarid regions. IEEE Trans. Geosci. Remote Sens., 22(4): 383-388.
[3] Fan K G, Huang W G, He M X, et al. 2012. Marine atmospheric boundary layer depth retrieval by SAR in China Sea. Chinese J. Geophys. (in Chinese), 55(4): 1137-1143, doi: 10.6038/j. issn.0001-5733.2012.04.009.
[4] Freeman A. 2004. Calibration of linearly polarized polarimetric SAR data subject to Faraday rotation. IEEE Trans. Geosci. Remote Sens., 42(8): 1617-1624.
[5] Hu C, Long T, Zeng T, et al. 2011. The accurate focusing and resolution analysis method in geosynthechronous SAR. IEEE Trans. Geosci. Remote Sens., 49(10): 3548-3563.
[6] Jehle M, Frey O, Small D, et al. 2010. Measurement of ionospheric TEC in spaceborne SAR data. IEEE Trans. Geosci. Remote Sens., 48(6): 2460-2468.
[7] Knepp D L. 1985. Aperture antenna effects after propagation through strongly disturbed random media. IEEE Trans. Antennas Propagt., 33(10): 1074-1084.
[8] Knepp D L, Brown W A. 1997. Average received signal power after two-way propagation through ionized turbulence. Radio Sci., 32(4): 1575-1596.
[9] Lawrence R S, Little C G, Chivers H J A. 1964. A survey of ionospheric effects upon earth-space radio propagation. Proc. IEEE, 52(1): 4-27.
[10] Li C S, Yang W, Wang P B. 2013. A review of spaceborne SAR algorithm for image formation. Journal of Radars (in Chinese), 2(1): 111-122.
[11] Li L, Dong Z. 2009. High resolution imaging of VHF/UHF P band SAR with presence of ionospheric affects. Computer Engineering and Applications (in Chinese), 45: 177-180.
[12] Li L, Hong J, Ming F, et al. 2012. An approach for ionospheric effects correction on spaceborne SAR calibration based on active radar calibrator. Journal of Electronics & Information Technology (in Chinese), 34(5): 1096-1101.
[13] Li L L, Li F. 2007. SAR imaging degradation by ionospheric irregularities based on TFTPCF analysis. IEEE Trans. Geosci. Remote Sens., 45(5): 1123-1130.
[14] Liu J. 2003. Ionospheric effects on Synthetic Aperture Radar Imaging[Ph. D. thesis]. Seattle, WA: Dept. Elect. Eng., Univ. Washington.
[15] Liu J, Kuga Y, Ishimaru A, et al. 2003. Ionospheric effects on SAR imaging: a numerical study. IEEE Trans. Geosci. Remote Sens., 41(5): 939-947.
[16] Meyer F, Bamler R, Jakowski N, et al. 2006. The potential of low-frequency SAR systems for mapping ionospheric TEC distributions. Geoscience and Remote Sensing Letters, IEEE, 3(4): 560-564.
[17] Meyer F J, Nicoll J B. 2008. Prediction, detection, and correction of faraday rotation in Full-Polarimetric L-Band SAR data. IEEE Trans. Geosci. Remote Sens., 46(10): 3076-3086.
[18] Rignot E J, Zimmermann J R, Van zyl J J. 1995. Spaceborne applications of P-band imaging radars for measuring forest biomass. IEEE Trans. Geosci. Remote Sens., 33(5): 1162-1169.
[19] Rosen P A, Hensley S, Chen C. 2010. Measurement and mitigation of the ionosphere in L-band interferometric SAR data. // Proceeding of 2010 IEEE Radar Conference. Washington, DC: IEEE: 1459-1463.
[20] Tsynkov S V. 2009. On SAR imaging through the Earth's ionosphere. SIAM J. Imaging Sci., 2(1): 140-182.
[21] Xu Z W, Wu J, Wu Z S. 2004. A survey of ionospheric effects on space-based radar. Waves Random Media., 14(2): S189-S273.
[22] Xu Z W. 2005. Ionospheric effects on satellite radio signal propagation and its performace (in Chinese) [Ph. D. thesis]. Shannxi: Xidian University.
[23] Xu Z W, Wu J, Wu Z S. 2008. Potential effects of the ionosphere on space-based SAR imaging. IEEE Trans. Antennas Propag., 56(7): 1968-1975.
[24] Zhu L, Guo W, Yu W D. 2009. Analysis of SAR satellite development history and tendency. Modern Radar (in Chinese), 31(4): 5-10.
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