共查询到20条相似文献,搜索用时 796 毫秒
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实践四号卫星遨游太空成果斐然由中国空间技术研究院所属的北京空间飞行器总体设计部研制的实践四号空间探测卫星自今年2月8日按预定程序进入地球同步转移轨道顺利飞行到9月上旬,卫星已绕地球飞行近500圈,接收的空间探测和工程试验信息约1000兆比特(1000... 相似文献
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卫星表面充放电是危害地球同步轨道卫星的严重问题,BM2表面充电试验设备是用于地球同步轨道卫星表面样品和外露组件表面充电效应研究和试验的设备,设备由真空设备、电子枪、紫外辐照装置和测量仪器组成,它是国内尺寸最大性能最好的表面充电试验设备。本文详细介绍了设备的组成和主要技术性能。 相似文献
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Shang Shang Zhang Qinyu Li Hui 《遥测遥控》2007,(4)
在深空通信中,由于信号传输距离遥远,功率受限的下行链路信号衰减巨大。为解决上述问题,分析地球大气层和外层自由空间的传输特性差异,提出以地球同步轨道卫星为中继站的下行链路的构想,根据每一段链路特性的不同选择载波频率。仿真结果表明,中继链路可以提高信号传输的信噪比、增大信道容量、降低误码率,提高了深空通信下行链路的可靠性。 相似文献
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2010年12月27日.欧洲通信卫星公司的“Ka星”由俄罗斯质子M运载火箭发射升空。卫星经过9小时12分钟的飞行.与火箭分离.进入地球同步转移轨道.太阳电池阵展开.控制中心成功获取卫星遥测信号。按计划,卫星最终定位在东经9度的工作轨道。“Ka星”计划2011年5月底进入商业运行,之前需要经过三个重要阶段.第一阶段为卫星调轨.包括发射7天后的4次远地点发动机点火。第二阶段为卫星定点在东经9度后将进行的一系列在轨测试。第三阶段为卫星与地面站的测试验证。 相似文献
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陆地卫星-D是美国新一代实验型的地球资源遥感卫星。1979年初由通用电气公司开始研制。今年6月发射,进入705公里高的圆形太阳同步轨道。星上遥感器的地面扫描宽度为185公里,每隔16天可对全球重复覆盖一次。卫星入轨后改称陆地卫星-4。 相似文献
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Bi-directional ground-to-satellite laser communication experiments were successfully performed between the optical ground station developed by the National Institute of Information and Communications Technology (NICT), located in Koganei City in suburban Tokyo, and a low earth orbit (LEO) satellite, the “Kirari” Optical Inter-orbit Communications Engineering Test Satellite (OICETS). The experiments were conducted in cooperation with the Japan Aerospace Exploration Agency (JAXA), and called the Kirari Optical communication Demonstration Experiments with the NICT optical ground station (or KODEN). The ground-to-OICETS laser communication experiment was the first in-orbit demonstration involving the LEO satellite. The laser communication experiment was conducted since March 2006. The polarization characteristics of an artificial laser source in space, such as Stokes parameters, and the degree of polarization were measured through space-to-ground atmospheric transmission paths, which results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography on a global scale in the future. The Phase-5 experiment, international laser communications experiments were also successfully conducted with four optical ground stations located in the United States, Spain, Germany, and Japan from April 2009 to September 2009. The purpose of the Phase-5 experiment was to establish OICETS-to-ground laser communication links from the different optical ground stations and the statistical analyses such as the normalized power, scintillation index, probability density function, auto-covariance function, and power spectral density were performed. Thus the applicability of the satellite laser communications was demonstrated, aiming not only for geostationary earth orbit-LEO links but also for ground-to-LEO optical links. This paper presents the results of the KODEN experiments and mainly introduces the common analyses among the different optical ground stations. 相似文献
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卫星通信因通信距离远、覆盖面积大、机动灵活等优势,广泛应用在抗震救灾、广播电视与移动通信中。然而,卫星通信因长距离通信和环境对信号的阻塞等问题,导致通信质量下降。为提高卫星通信质量,可以增加地面站发射功率或者采用分集技术。由于电磁波具备极化特性,左旋圆极化电磁波与右旋圆极化电磁波相互正交,利用其正交特性可实现长距离通信中传输路径相互独立,可以应用于星地MIMO通信中。主要研究双圆极化分集2×2 MIMO相关内容,对开阔环境和城市环境的信道参数进行研究,建立了窄带卫星双圆极化卫星2×2 MIMO信道模型,设计了一套具备在地面模拟双圆极化卫星和个人移动终端收发系统,并在该系统上验证双圆极化分集2×2 MIMO,相比于SISO获得的信噪比改善。 相似文献
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GEO卫星表面充电相对电位的工程分析 总被引:1,自引:0,他引:1
地球静止轨道(GEO)卫星在轨运行期间,沉浸于具有一定能量和密度的空间等离子体之中,等离子体与卫星表面材料相互作用,将使卫星出现"表面充/放电效应",进而对星上电子系统产生影响,甚至发生电路故障,直接威胁整星安全。为防止GEO卫星在轨期间因等离子体造成的表面充放电导致卫星异常和故障,在GEO卫星的设计中,必须进行卫星表面电位分析、控制和试验验证等工作。文章根据卫星表面材料的基本参数和接地状态,采用工程分析方法对卫星表面充电电位进行分析,满足卫星工程设计急需。 相似文献
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《Acta Astronautica》2014,93(2):476-486
A deterministic (non-statistical) two dimensional (2D) computational model describing the transport of electron and photon typical of space radiation environment in various shield media is described. The 2D formalism is casted into a code which is an extension of a previously developed one dimensional (1D) deterministic electron and photon transport code. The goal of both 1D and 2D codes is to satisfy engineering design applications (i.e. rapid analysis) while maintaining an accurate physics based representation of electron and photon transport in space environment. Both 1D and 2D transport codes have utilized established theoretical representations to describe the relevant collisional and radiative interactions and transport processes. In the 2D version, the shield material specifications are made more general as having the pertinent cross sections. In the 2D model, the specification of the computational field is in terms of a distance of traverse z along an axial direction as well as a variable distribution of deflection (i.e. polar) angles θ where −π/2<θ<π/2, and corresponding symmetry is assumed for the range of azimuth angles (0<φ<2π). In the transport formalism, a combined mean-free-path and average trajectory approach is used. For candidate shielding materials, using the trapped electron radiation environments at low Earth orbit (LEO), geosynchronous orbit (GEO) and Jupiter moon Europa, verification of the 2D formalism vs. 1D and an existing Monte Carlo code are presented. 相似文献
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星载微波辐射计通道分辨率匹配技术及其在FY-3卫星MWRI中的应用 总被引:2,自引:1,他引:2
基于仿真模型对圆锥扫描星载微波成像仪不同频率和极化二维天线方向图地面足迹的模拟,对FY-3卫星微波成像仪(MWRI)原始观测轨道亮温数据,用Backus-Gilbert(BG)分辨率匹配算法分别对分辨率降低(高频通道匹配到低频通道)和分辨率增强(低分辨率匹配到高分辨率)进行了实验分析。结果表明:分辨率降低匹配处理能较好地模拟实际仪器观测,且不另引入噪声,可在MWRI通道分辨率匹配中实际应用;分辨率增强匹配可明显提高低频图像分辨率,但会一定程度引入噪声,实际应用中应考虑在分辨率增强与噪声间进行折中处理,在增强分辨率的同时,使引入的噪声在可接受范围内。 相似文献
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随着自动驾驶、精密农业等领域的发展,各领域对高精度导航定位的需求不断增加。在地基增强技术、高轨星基增强技术和传统非差精密单点定位技术的基础上,提出了一种基于低轨卫星增强的非差高精度导航定位技术,研制了基于低轨导航增强技术的低轨导航增强载荷,开发了基于低轨卫星增强的地面自适应卡尔曼滤波非差高精度定位软件,并进行了全球首次基于低轨卫星的信号信息一体化导航增强在轨试验。试验表明:经低轨卫星增强后,地面终端用户定位精度优于30 cm。最后,给出了该技术的后续研究方向,为未来低轨导航增强系统与其他增强系统协同工作,实现广泛应用奠定了基础。 相似文献
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在卫星动力法定轨的协方差分析基础上,提出了一种针对地球静止轨道(GEO)卫星的简化定轨精度分析方法。根据GEO卫星的线性化状态转移方程,通过设定地面跟踪网坐标和卫星星下点经度计算叠加矩阵,由观测弧长和采样间隔直接计算定轨精度评定公式中的主要部分。公式扩展后,能比较各种系统误差源对定轨精度的影响,并将影响较大的作为附加参数纳入估计过程并重新评价定轨精度。用该法对10 m定轨精度的测距跟踪网优化设计和测距偏差对定轨精度的影响特性进行分析的结果表明,测量系统中的系统性误差可能以近20的放大倍率传播到卫星沿迹方向和法向,且不能通过自校准测距常值偏差提高定轨精度。 相似文献