共查询到18条相似文献,搜索用时 140 毫秒
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水下目标回波图像涉及到声散射问题,为提高目标回波求解效率,传统解析方法对水下非刚性目标回波求解过程复杂,难以在工程上广泛应用。根据主动声纳线性目标模型,引用界面附近目标回波的物理声学(Kirchhoff近似)方法,建立了平台机动条件下目标回波图像的仿真方案。在混响背景下对回波信号时域波形的后置处理,利用Matlab编程软件生成了比较真实的方位—距离联合表示的二维回波图像,读取图像要素可以达到对目标定位及识别的目的。仿真结果表明,目标回波的求解过程方便易行,仿真图像逼真地反映了平台机动时目标回波图像的对应变化,实现了对目标的有效定位。方法对模拟训练领域具有重要的应用价值,可以用于高频图像声纳模拟软件平台的研制。 相似文献
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刘成元 《计算机与数字工程》2012,40(5):146-148
针对传统亮点模型模拟水下目标回波亮点精确度不高的问题,给出了一种运用板块元法仿真实现目标回波亮点的方法。采用建模软件对潜艇模型进行精确几何建模,运用板块元法计算了潜艇目标的高频回波数据。仿真结果表明:该方法可以更真实地反应水下目标的回波亮点特性,为水下目标的探测与识别提供数据支持。 相似文献
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地理环境的场景回波模拟直接影响到合成孔径雷达(SAR)对抗系统仿真试验的效能评估.通过分析研究场景地表地物的电磁特性,利用高分辨率卫星影像数据的地物特征,采用面向对象的多尺度分类分割算法,提取得到了真实地物电磁特性数据.在构建分布目标模型时,先将实测数字高程模型(DEM)数据进行分形插值处理,建立几何模型,再利用小面单元模型建立散射模型,小面单元的电磁散射特性数据由与DEM数据对应区域的卫星影像数据提取得出,从而建立真实地理环境的SAR回波模型.通过ChirpScaling成像算法对回波信号进行处理,证明了方法的可行性.得到的场景回波模型与通常所用的忽略地物电磁特性得到的回波模型相比,具有逼真度高的优点,为SAR对抗系统仿真试验提供支持. 相似文献
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在海面目标的声纳探测优化的研究中,由于回波信号受随机界面的干扰影响,主动声纳探测海面目标比较困难。由于传统的解析方法求解回波的过程复杂,根据存在界面时声散射的Kirchhoff近似公式,建立了一种海面目标的声散射模型,导出了目标回波特性的预报公式,并仿真分析了入射波频率和掠射角变化对海面目标回波的影响。结果表明:海面附加回波对直达目标的镜反射波造成不同程度的干扰,合理调整声波掠射角有利于目标探测和特征识别,并对提高声纳探测海面目标的准确性提供了科学依据。 相似文献
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随着水声技术的发展,水下武器对抗也日趋复杂。能够模拟目标回波的主动式声诱饵的出现,为对抗主动自导鱼雷及主动声纳提供了非常重要的帮助。着重对声诱饵的回波模拟器的作用机理进行了分析,然后给出了脉冲宽度、多普勒频移、时延与展宽、目标强度:最大回波强度等回波特征参数的估计方法,并对可以同时对抗声自导鱼雷和主动声纳的某声诱饵回波模拟器进行了仿真研究,并给出了仿真结果,对水声对抗技术研究有着重要的参考价值。 相似文献
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主动声纳目标探测中,水雷等浅海安静型小目标声散射回波受海洋环境干扰严重,影响对目标特征的准确提取与识别,探测可靠性低.针对上述问题,研究一种结合形态学滤波的时频域盲分离算法,根据主动声纳回波中目标与混响的时频特征差异,设计形态学结构元的几何结构,滤除与目标谱不重叠的混响及互项干扰,再利用波形聚类方法优化与目标谱重叠的混响干扰,突出目标亮点的时频谱线,得到目标声散射的自项时频信息,最后获得目标亮点的时频域解混矩阵,分离出目标声散射信号.数值仿真结果表明,结合形态学滤波的时频域盲分离算法,提高了目亮点信号的信混比. 相似文献
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Empirical results illustrate the pitfalls of applying an artificial neural network (ANN) to classification of underwater active sonar returns. During training, a back-propagation ANN classifier learns to recognize two classes of reflected active sonar waveforms: waveforms having two major sonar echoes or peaks and those having one major echo or peak. It is shown how the classifier learns to distinguish between the two classes. Testing the ANN classifier with different waveforms of each type generated unexpected results: the number of echo peaks was nor the feature used to separate classes. 相似文献
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Jie Huang Tadawute Supaongprapa Ikutaka Terakura Fuming Wang Noboru Ohnishi Noboru Sugie 《Robotics and Autonomous Systems》1999,27(4):199-209
This paper describes a mobile robot equipped with a real time sound localization system as well as a sonar system for obstacle detection. The sound localization method is based on a model of the precedence effect of the human auditory system to cope with echoes and reverberations. Sound localization and robot navigation experiments were conducted. The results show that the robot is capable of localizing sounding objects in a reverberant environment and approaching the objects without collisions, even when the objects were behind obstacles. Environment flexibility and error robustness of the system were discussed as well. 相似文献
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干涉条纹特征是主动声呐目标识别所依据的重要特征之一。在浅水域环境中,声波能量传播特性较为复杂,信号会经过发射源到目标以及目标到接收器这2条不同的路径,目标的散射特性在声波的入射模式和散射模式之间相互作用,使得主动声呐干涉条纹呈现弯曲的结构。为对干涉条纹特征进行表征,提出一种基于曲率和的声呐特征提取方法。根据浅海声场主动声呐频率-距离干涉条纹图得到一段区间内的干涉条纹曲线散点曲率值,利用曲率求和的方法刻画条纹的弯曲程度,进而表征这一区间内的条纹特征。在理想波导环境下计算刚性球体目标在不同频率段下的曲率特征,通过统计平均值的方式得到平均曲率和为0.6左右,从特征表征结果可以看出,曲率和可通过统计离散点曲率强度描述干涉条纹特征,且在同一环境条件下,发射频率越大时曲率和强度越小。根据实测数据进行计算得到曲率和为0.512,实验与理论结果较为吻合,表明通过该方法可以获取主动声呐干涉条纹特征,进而实现目标识别和探测。 相似文献
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In October 2005, the Samho Brother, a 90 m long chemical tanker ship, sank 74 m deep in the Taiwan Strait off the Hsinchu coast. The ship was transporting benzene and marine fuel. In April 2009, an attitude survey of the sunken ship was conducted to prevent further environmental damage that may arise from chemical spillage. The survey used multi-beam echo sounders and side-scan sonar systems. However, attitude estimations using multi-beam data only gave the vessel's laying angle, with large variations, at around 14° roll direction. This value was suspicious because 1.5° footprints of multi-beam echoes were too large for deep and acoustic waves that could easily bounce on the wreckage. With detailed mapping using the side-scan sonar approach, different sonographs of the sunken vessel were obtained from different scanning attitudes and angles standing more than 10 m above the seafloor. In this study, an estimation of target heights was demonstrated to determine the correct procedures in handling side-scan sonar schemes. It is proposed that the Samho Brother had transversely rotated; its port was at an upward position relative to its side, which was lying on the seafloor. It lies horizontally along the keel direction, but the surface of the hold (deck) level is tilted 18° vertically to the west. 相似文献
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为解决在海洋中大范围侦察和监视目标的问题,对声纳组网进行建模和仿真:给出了被动声纳基阵布阵的两种方法;应用单个被动声纳测向,两个或两个以上的被动声纳阵求解目标运动参数;考虑到声传播损失受海况的影响,对传播损失采用通用计算公式;对被动声纳接收到的信号进行谱分析,利用数据库对目标进行识别,达到实时大范围侦察和监视的目的.依次进行建模,利用Visual C 编制仿真程序,使仿真数据可视化.结果表明上述方法在被动声纳组网仿真中是可行的和有效的. 相似文献
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Jong Hwan Lim Leonard J.J. 《IEEE transactions on pattern analysis and machine intelligence》2000,22(9):1035-1041
This paper presents a method for relocation of a mobile robot using sonar data. The process of determining the pose of a mobile robot with respect to a global reference frame in situations where no a priori estimate of the robot's location is available is cast as a problem of searching for correspondences between measurements and an a priori map of the environment. A physically-based sonar sensor model is used to characterize the geometric constraints provided by echolocation measurements of different types of objects. Individual range returns are used as data features in a constraint-based search to determine the robot's position. A hypothesize and test technique is employed in which positions of the robot are calculated from all possible combinations of two range returns that satisfy the measurement model. The algorithm determines the positions which provide the best match between the range returns and the environment model. The performance of the approach is demonstrated using data from both a single scanning Polaroid sonar and from a ring of Polaroid sonar sensors 相似文献