共查询到19条相似文献,搜索用时 152 毫秒
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雷达回波信号的获取对研究动态目标识别和雷达成像具有十分重要的意义。提出了一种基于时域弹跳射线法(Time Domain Shooting and Bouncing Ray, TDSBR)的动态目标回波仿真模型,用于模拟海上电大目标的近场雷达回波。该模型采用TDSBR方法直接在时域计算弹载雷达照射下的目标与海面近场复合散射特性,并结合“stop-go”方法模拟雷达与目标之间的相对运动,实现了弹载雷达照射下海上运动舰船目标的回波信号仿真。仿真结果表明,该模型可以有效呈现海面与海上目标的耦合效应,实现对目标速度和距离的预测,具有良好的精度和较高的效率,在海洋环境中弹载雷达的回波预测和目标检测中具有广阔的应用前景。 相似文献
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运用基于图像特征和基于回波信号这两种SAR图像仿真方法,对海面舰船进行SAR成像仿真。根据仿真参数和得到的仿真图像,对比两种方法的优缺点。将基于海浪谱的双尺度动态海面模型和其上舰船3D模型组合,构成海面舰船三维复合模型,并运用小面单元模型,通过射线追踪法(SBR)处理面元之间的遮挡阴影问题,结合物理光学法(PO)来计算面元的散射截面,然后分别基于图像特征和基于回波信号进行SAR图像仿真。得到的仿真图像能较直观地反映两种仿真方法的优缺点。 相似文献
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随机粗糙海面的多路径海杂波频谱数值模拟 总被引:1,自引:1,他引:0
海杂波干扰影响雷达制导性能,对各海况物理条件下海杂波的数值模拟可用于实验室海杂波仿真、制导雷达的设计、监测性能的分析等.本文采用一种海面起伏双尺度近似模型进行多路径海杂波频谱的数值模拟,通过谱拟合模拟时变随机粗糙海面,计算收发高度和间距给定条件下海面多路径有效散射面积,计算接收点电场强度、雷达双站散射系数以及接收点功率谱密度(海杂波频谱). 相似文献
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海面掠入射散射特性对海洋遥感等问题有着重要应用,海面对雷达波束的镜面反射对海上超低空目标与海面的耦合场有着重要影响,利用海面的布儒斯特效应将有效削弱镜面反射。以西太平洋和东南沿海盐度场与温度场的卫星数据为基础,根据双Debye方程建立修正海水介电模型计算不同海域介电常数;基于Elfouhaily海谱模型,采用修正双尺度模型并考虑不同风速及频率下的截断波数,仿真分析了风速、频率、海水温度与盐度等因素对海面掠入射散射特性及布儒斯特效应的影响,总结归纳了海面布儒斯特效应产生机理和变化规律。分析表明:风速、频率及海水温度均会对海面布儒斯特效应产生影响。该研究为海洋环境的遥感探测及海上超低空目标的监测与跟踪提供了理论支撑。 相似文献
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海洋内波通常在海面之下传播,并通过波流相互作用影响海洋表面毛细波的分布,在合成孔径雷达(SAR)图像中表现为亮暗相间的纹理.该文首先基于Korteweg-de Vries(KdV)方程,建立内波传播模型;通过波流相互作用函数,基于波作用量方程,对表面毛细波的波谱进行修正;最后基于双尺度方法的面元模型,将内波对高频谱的修正作用考虑在内,计算内波的存在对大尺寸海面电磁散射特性的影响.文中计算了内波存在时海面散射系数分布,分析了不同的内波参数,不同海况参数等对海面散射系数和多普勒的影响. 相似文献
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弹载SAR岛屿海岸线景象匹配成功概率与实时图中海岸线形状密切相关,海岛环境下海浪和地形起伏等因素对海岸线在SAR图像中的特征具有不可忽略的影响,造成海岸线的模糊和变形。首先分析了海岛环境弹载SAR图像的特点,然后基于海浪频谱和方向谱相关经验公式,利用线性叠加方法给出了详细的海浪仿真的实现过程;建立了海岛高程起伏的二维指数函数模型;利用波数域方法给出了典型场景下的海岛SAR图像仿真结果,并在此基础上分析了海浪和山峰对弹载SAR图像海岸线检测的影响和基于SAR图像的海岸线检测方法局限性。研究结果表明基于SAR回波数据的海岸线检测方法是一种适于弹载SAR应用的有效方法。 相似文献
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The simulation of the SAR image of a ship wake 总被引:4,自引:0,他引:4
Tunaley J.K.E. Buller E.H. Wu K.H. Rey M.T. 《Geoscience and Remote Sensing, IEEE Transactions on》1991,29(1):149-156
A computer simulation of L -band SAR (synthetic aperture radar) images of surface-ship wakes is described, and the simulation results are compared to actual Seasat, satellite-borne SAR imagery. The model used in the simulation accounts for both the disturbance produced in the water by the moving ship and the influence of the background sea. The radar scatter from the wake is modeled using the Bragg mechanism. A two-scale model of the sea surface is employed in which it is assumed that the small-wavelength Bragg waves are modulated by the larger-scale ambient sea and wake fluctuations. The larger-scale fluctuations are important because they can alter the local angle of incidence and thus cause a tilt modulation in the scattering coefficient. Several components of the wake are modeled: the ambient waves, the Kelvin wake, and the turbulent wake. The model can produce long turbulent wakes, which may be bright or dark, depending on the geometry of the ship, radar, and wind, and it can produce Kelvin wakes 相似文献
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The full wave approach is used to derive a unified formulation for the like and cross polarized scattering cross sections of composite rough surfaces for all angles of incidence. Earlier solutions for electromagnetic scattering by composite random rough surfaces are based on two-scale models of the rough surface. Thus, on applying a hybrid approach physical optics theory is used to account for specular scattering associated with a filtered surface (consisting of the large sonic spectral components of the surface) while perturbation theory is used to account for Bragg scattering associated with the surface consisting of the small scale spectral components. Since the full wave approach accounts for both specular point scattering and Bragg scattering in a self-consistent manner, the two-scale model of the rough surface is not adopted in this work. These unified full wave solutions are compared with the earlier solutions and the simplifying assumptions that are common to all the earlier solutions are examined. It is shown that while the full wave solutions for the like polarized scattering cross sections based on the two-scale model are in reasonably good agreement with the unified full wave solutions, the two solutions for the cross polarized cross sections differ very significantly. 相似文献
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基于蚁群算法的InSAR相位解缠算法 总被引:8,自引:0,他引:8
该文利用数字地面高程(DEM)数据的变更,由SAR成像机理和双尺度粗糙面散射计算构造得到多景具不同阴影的单视复数(SLC)SAR影像数据。提出一种基于蚁群算法的相位解缠算法,用于多景具不同残差点数量的仿真相干SLC相干图像以及欧洲环境卫星(ENVISAT-ASAR)的InSAR图像的相位解缠,并与其他现有的解缠方法作比较。结果表明:该算法是一种有效的相位解缠方法,解缠精度与解缠速度上要优于其他一些常用的解缠方法。 相似文献
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There has been an increasing interest in the applications of polarimetric microwave radiometers for ocean wind remote sensing. Aircraft and spaceborne radiometers have found a few Kelvins wind direction signals in sea surface brightness temperatures, in addition to their sensitivities to wind speeds. However, it was not clear what physical scattering mechanisms produced the observed brightness dependence on wind direction. To this end, polarimetric microwave emissions from wind-generated sea surfaces are investigated with a polarimetric two-scale scattering model, which relates the directional wind-wave spectrum to passive microwave signatures of sea surfaces. Theoretical azimuthal modulations are found to agree well with experimental observations for all Stokes parameters from near nadir to 65° incidence angles. The upwind and downwind asymmetries of brightness temperatures were interpreted using the hydrodynamic modulation. The contributions of Bragg scattering by short waves, geometric optics scattering by long waves and sea foam are examined. The geometric optics scattering mechanism underestimates the directional signals in the first three Stokes parameters, and predicts no signals in the fourth Stokes parameter (V). In contrast, the Bragg scattering was found to dominate the wind direction signals from the two-scale model and correctly predicted the phase changes of the upwind and crosswind asymmetries in Tυ and U from middle to high incidence angles. The phase changes predicted by the Bragg scattering theory for radiometric emission from water ripples is corroborated by the numerical Monte Carlo simulation of rough surface scattering. This theoretical interpretation indicates the potential use of polarimetric brightness temperatures for retrieving the directional wave spectrum of short gravity and capillary waves 相似文献
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基于点源扰动方法建立了舰船的Kelvin尾迹模型, 模拟了不同船速下的Kelvin尾迹.实际中, 舰船尾迹除了受到舰船自身参数影响外, 还会受到风驱海浪的调制.为了建立更为符合实际的Kelvin尾迹模型, 借助PM(Pierson-Moscowitz)海谱生成粗糙海面, 将其与Kelvin尾迹模型进行线性叠加后, 得到了粗糙海面上舰船尾迹.在该复合模型基础上, 利用物理光学法获得了不同入射情况下的单站、双站的雷达散射截面, 实现了海面舰船尾迹电磁散射的模拟仿真.这一过程的实现, 有利于更好地模拟舰船尾迹在合成孔径雷达(Synthetic Aperture Radar, SAR)中的成像仿真, 同时为SAR成像中舰船尾迹以及舰船自身的识别奠定了基础. 相似文献