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地形轮廓匹配(TERCOM)匹配算法在速度误差和航向误差较大的情况下可靠性下降,桑地亚惯性地形辅助导航(SITAN)算法在初始位置误差较大时Kalman滤波器不能收敛,针对以上问题,提出了一种新的适用航空的地形匹配导航算法.该算法采用基于地形剖面匹配系统(TERPROM)算法作为搜索算法,以基于扩展Kalman滤波原理的SITAN算法作为跟踪算法.将该算法在真实地形数据上仿真,并和传统的基于单状态并行Kalman滤波器阵列做搜索的SITAN算法在不同高度表噪声情况下比较.仿真结果表明,该算法有效地提高了搜索的效率,提高了地形匹配的精度及实用性. 相似文献
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《中国无线电电子学文摘》2002,(3)
TN96 02031642地形匹配辅助导航的地形适配性分析/齐战杰,高j ing(国防科技大学电子工程学院)11无线电工程一2 001,(增)一29一31,77文中应用数学统计理论的方法,研究地形匹配过程中各种地形参数对匹配效果的影响,对主要的几种统计特征和匹配参量进行了分析,讨论了其在地形匹配中作用的大小及相互关系;通过对典型地形计算结果的分析,得出了回归函数表达式.利用得到的结论进行适配性的分析,对于匹配系统中各种参数和地形适配区选取具有直接指导作用.图2表3参5(午)TN961一种G PS系统(哈尔滨工业大学) 02031643P码直接捕获策略分析/连全斌,… 相似文献
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研究了一种以干涉合成孔径雷达(InSAR)信息为基础的三维地形匹配导航系统,该系统采用基于3-D Zernike矩的三维地形匹配算法,同时针对3-D Zernike矩在地形匹配中计算实时性差的问题进行了改进。为验证系统的有效性和算法性能,搭建了基于VC++和OpenSceneGraph的三维可视化软件仿真平台。仿真结果表明,基于3-D Zernike矩的三维地形匹配算法定位精确度高,对地形的适应能力强,算法的实时性问题得到了良好解决,系统具有较高的工程实用价值。 相似文献
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多输入多输出(MIMO)雷达作为一种新型的雷达体制,其成像兼具高分辨率与实时性的优点。由于观测区域的稀疏性,MIMO雷达成像可以用压缩感知的方法进行处理。而现有的MIMO雷达稀疏成像的贪婪恢复算法中,正交匹配追踪算法(OMP)存在成像图像有伪影的缺点,子空间追踪算法(SP)则受到低分辨率的困扰。针对上述问题,该文提出一种称为混合匹配追踪算法的压缩感知贪婪算法以实现MIMO雷达稀疏成像。通过将两种贪婪恢复算法结合起来,利用OMP 算法选择基信号的正交性和SP 算法具有基信号选择的回溯策略,来重构出高分辨率且没有伪影的雷达图像。仿真实验验证了所提算法的有效性。 相似文献
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多视角穿墙雷达成像系统利用多个视角的目标回波数据,可以有效提高目标成像重建结果的质量。在建立多视角穿墙雷达联合稀疏信号模型的基础上,提出了一种基于交叉验证技术的删失同时正交匹配追踪成像算法。该算法将每个观测视角雷达单元的测量数据分成重建数据和交叉验证数据两部分,通过进行多次删失同时正交匹配追踪迭代计算实现测量噪声水平估计和成像重建,既减小了各个视角雷达站间的数据通信开销,也摆脱了成像算法对测量噪声水平和场景稀疏度先验信息的依赖。仿真实验结果验证了所提成像算法的有效性和准确性。 相似文献
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地形导航中的3D地形跟踪方法 总被引:1,自引:1,他引:0
地形跟踪技术是飞行器自动导航的基础,激光成像雷达可以高精度实时获取前视距离像和3D地形图,从激光成像雷达所成前视距离像中可以识别飞行器前下方的地形(包括障碍物),人而为飞行器毛皮地形跟踪提供基础,在飞行器惯性作用下,研究了飞行器自动障碍物回避方法,推导了飞行器与规划航迹之间的3D空间关系,以飞行器自动障碍物回避为基础,建立了飞行器沿规划航迹飞行的地形跟踪方程。在参考地形图上进行了仿真实验。结果表明,3D地形跟踪方法,能够很好的满足飞行器自动导航的要求。 相似文献
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基于格网模型的三维地形可视化 总被引:2,自引:0,他引:2
地形是自然界中具有复杂特征的景物之一,格网模型具有结构简单,数据直观的优点,是地形建模的有效模型.在地形建模的基础上,经过消隐处理、光照处理等处理过程后,可以实现三维真实感地形的显示.提出了基于格网模型的地形建模技术,并给出了消隐处理、光照处理的方法和实验结果,从而实现三维真实感地形的可视化. 相似文献
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Repeat-pass SAR interferometry over forested terrain 总被引:3,自引:0,他引:3
Hagberg J.O. Ulander L.M.H. Askne J. 《Geoscience and Remote Sensing, IEEE Transactions on》1995,33(2):331-340
Repeat-pass synthetic aperture radar (SAR) interferometry provides the possibility of producing topographic maps and geocoded as well as radiometrically calibrated radar images. However, the usefulness of such maps and images depends on our understanding of how different types of terrain affect the radar measurements. It is essential that the scene coherence between passes is sufficient. In this paper, the authors derive a general system model including both radar system and scene scattering properties. The model is used to interpret measurements over a forested area where the scene coherence varies between 0.2 and 0.5. The coherence is found to be sensitive to temperature changes around 0°C but surprisingly insensitive to wind speed. The interferometric height discontinuity at the forest to open-field boundary shows good agreement with in situ tree height measurements. For a dense boreal forest, but is observed to decrease for a less dense forest. This suggests the possibility of estimating bole volume from the interferometric tree height and a ground DEM. The decrease of scene coherence over a dense forest with increasing baseline is also used to estimate the effective scattering layer thickness 相似文献
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The availability of digital terrain models (DTM) or terrain data bases (TDB) has prompted the use of point-to-point prediction models to compute propagation losses due to terrain irregularity. Traditionally, area prediction models (like ITU-R Recommendation 370, Longley and Rice, etc) have been used for coverage computation. These models require very little information regarding terrain characteristics and provide poor accuracies. Here, an assessment of several point-to-point models using detailed terrain information and aimed to be used in radiocommunication planning tools based on TDBs is presented. Two main characteristics are considered for comparison, namely, accuracy and ease in terrain data handling 相似文献
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《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1967,55(9):1583-1590
The standing-wave method was used to measure the radar cross section σ of a flat piece of ground on which stood a single tree. Measurements were made at 26 MHz at angles of elevation γ up to 22.5 degrees, by raising the transmitting antenna with a balloon and moving the receiving probe along the transmitter-target line by means of ropes. For horizontal polarization, σ was a smoothly increasing function of γ. For "vertical" polarization (polarization parallel to the plane of incidence on the ground), σ increased rapidly up to 10 degrees, then became fairly constant with a value of 6 m2. The sudden change in the slope of σ(γ) is the knee effect suggested by previous observations. The Brewster angle was 14 degrees, consistent with a theory that the knee should occur a few degrees below the Brewster angle. Below 15 degrees, the cross section for vertical polarization was greater than that for horizontal polarization by as much as 30 dB. 相似文献
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Backscatter measurements of snow-covered terrain have been made using a polarimetric frequency-agile experimental 94-GHz radar. The radar scanned snow surfaces at radar depression angles varying from 15 to 55°. Data collection using the polarimetric and frequency-agile radar along with concurrent detailed snow characterization measurements was performed. Typical results for the temporal and spatial variability of the snow reflectivity are presented and discussed 相似文献
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《Vehicular Technology, IEEE Transactions on》1977,26(4):335-340
Field strength patterns have been recorded in Sweden (deep woods, hilly terrain), Norway (long narrow valleys), and Denmark (farmland, urban districts). Digital processing of recordings has taken place. Examples of amplitude distributions are presented for various types of terrain. Results show good agreement with the Rayleigh distribution in spite of the great difference in type of terrain. 相似文献