电离层色散效应对星载SAR成像的影响
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摘要
SAR信号传播过程中受到电离层色散效应的影响,不同频率的信号传播速度会出现差异。对于宽带线性调频信号,色散效应导致SAR信号产生传播时延,引入附加的超前相位。通过时域仿真方法仿真并分析不同载频、不同带宽、不同电离层TEC值和不同方位分辨率条件下,电离层色散效应对SAR成像的影响。结果表明电离层色散效应造成SAR图像距离向偏移、旁瓣升高和脉冲展宽等问题。P波段和L波段受电离层色散效应影响较为明显。C波段和X波段高分辨率星载SAR,信号带宽载频比值较大时,电离层色散效应的影响导致成像质量下降。
In the process of SAR signal propagation, the velocities of signal propagating at different frequencies are different due to the ionospheric dispersion effect. For the LFM signal with wide bandwidth, the dispersion effect results in the propagation delay of SAR signal, leading to additional advanced phase. In this study, the effects of ionospheric dispersion on SAR imaging under different carrier frequencies, different bandwidths, and different ionospheric TEC values are simulated and analyzed by using the time-domain simulation method. The results show that the ionospheric dispersion effect causes the SAR image to be shifted in distance with the sidelobe increase and pulse broadening. The P-band and L-band are obviously affected by the ionospheric dispersion effect. For C-band and X-band high resolution spaceborne SAR, the ionospheric dispersion effect leads to the degradation of imaging quality when the signal bandwidth carrier ratio is large.
In the process of SAR signal propagation, the velocities of signal propagating at different frequencies are different due to the ionospheric dispersion effect. For the LFM signal with wide bandwidth, the dispersion effect results in the propagation delay of SAR signal, leading to additional advanced phase. In this study, the effects of ionospheric dispersion on SAR imaging under different carrier frequencies, different bandwidths, and different ionospheric TEC values are simulated and analyzed by using the time-domain simulation method. The results show that the ionospheric dispersion effect causes the SAR image to be shifted in distance with the sidelobe increase and pulse broadening. The P-band and L-band are obviously affected by the ionospheric dispersion effect. For C-band and X-band high resolution spaceborne SAR, the ionospheric dispersion effect leads to the degradation of imaging quality when the signal bandwidth carrier ratio is large.
引文
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[13] 苏星伊,邢孟道,周芳,等.SAR成像中电离层的影响估计及其补偿[J].中国科技论文,2016,11(14):1 600-1 604.
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[16] 姚佰栋,时晶晶.电离层对星载P波段合成孔径雷达成像的影响[J].无线互联科技,2015(5):139-142.
[17] 李力.星载P波段合成孔径雷达中的电离层效应研究[D].长沙:国防科学技术大学,2014.
[2] 崔丽萍,王晓青.SAR影响建筑物震害检测方法研究综述[J].震灾防御技术,2016,11(2):239-250.
[3] 范剑超,王德毅,赵建华,等.高分三号SAR影像在国家海域使用动态监测中的应用[J].雷达学报,2017,6(5):456-472.
[4] 王岩飞,刘畅,詹学丽,等.无人机载合成孔径雷达系统技术与应用[J].雷达学报,2016,5(4):333-349.
[5] Belcher D P.Ionospheric effects on synthetic aperture radar clutter statistics[J].IET Radar,Sonar&Navigation,2013,7(9):1 004-1 011.
[6] Cao P,Xing M D,Sun G C,et al.Minimum entropy via subspace for ISAR autofocus radar[J].Geoscience and Remote Sensing Letters,2010,7(1):205-209.
[7] Liu J,Kuga Y,Ishimaru A.Ionospheric effects on SAR imaging:a numerical study[J].IEEE Transactions on Geoscience and Remote Sensing,2003,41:937-947.
[8] Jehle M,Frey O,Small D,et al.Measurement of ionospheric TEC in spaceborne SAR data[J].IEEE Trans Geosci,RemoteSens,2010,48(6):2 460-2 468.
[9] 李亮,洪峻,明峰,等.一种基于有源定标器的电离层对星载SAR定标影响校正方法[J].电子与信息学报,2012,34(5):1 096-1 101.
[10] 赵宁,谈璐璐,张永胜,等.星载P波段SAR电离层效应的双频校正方法[J].雷达科学与技术,2013,11(3):255-261.
[11] 赵宁,周芳,王震,等.P波段雷达成像电离层效应的地面观测与校正[J].雷达学报,2014,3(1):45-52.
[12] 王成,张民,许正文,等.基于星载SAR信号的TEC反演新方法[J].地球物理学报,2014,57(11):3 570-3 576.
[13] 苏星伊,邢孟道,周芳,等.SAR成像中电离层的影响估计及其补偿[J].中国科技论文,2016,11(14):1 600-1 604.
[14] Xu Z W,Wu J,Wu Z S.A survey of ionospheric effects on space-based radar[J].Waves in Random Media,2004,14(2):S189-S273.
[15] 焦培南,张忠治.雷达环境与电波传播特性[M].北京:电子工业出版社,2007.
[16] 姚佰栋,时晶晶.电离层对星载P波段合成孔径雷达成像的影响[J].无线互联科技,2015(5):139-142.
[17] 李力.星载P波段合成孔径雷达中的电离层效应研究[D].长沙:国防科学技术大学,2014.