共查询到20条相似文献,搜索用时 62 毫秒
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双星系统工作方式改进的探讨 总被引:7,自引:1,他引:6
本文对北斗卫星导航系统工作方式的某些改进方法进行了探讨,借助于这些改进可以使北斗系统作无节点,无源,实时工作。作者对这些改进措施进行了计算机仿真,所得改善结果明显。 相似文献
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北斗三星无源定位技术 总被引:6,自引:2,他引:4
介绍了北斗双星定位系统的特点、功能、系统组成和工作原理,说明了北斗有源定位方式在应用方面的局限性。针对北斗有源定位方式不能无线电静默,和人们对具有无线电隐蔽性的卫星定位的需求,详细介绍一种北斗三星无源定位技术:包括工作原理、实现方法、定位精度分析和目前达到的定位精度。阐述了北斗三星无源定位技术的优点和应用形势。 相似文献
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“北斗”卫星系统的陆基增强方案探讨 总被引:2,自引:1,他引:1
简要介绍了“北斗一号”卫星系统的组成与工作原理,着重对“北斗”陆基增强方案进行了分析。增强后的“北斗”系统用户端安装导航处理器,工作方式为被动无源工作模式,分析表明,对“北斗”增加陆基系统,大大提高了导航的可靠性,减小几何精度系数,提高定位精度。 相似文献
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针对北斗双星定位系统的有源定位方式,提出了北斗三星无源定位技术,但是北斗三星无源定位的精度不高,难以满足某些用户的要求。为此,借鉴GPS差分定位,介绍了一种可提高北斗无源定位精度的北斗局域差分技术,包括工作原理、被采用的原因和使用条件等。最后详细阐述了研制北斗无源局域差分定位设备的作用和意义。 相似文献
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针对通信过程中超短波电台被窃听或干扰后空地双方无法建立通信的情况,设计一种基于北斗卫星导航系统短消息的电台参数无线注入系统.系统可根据指挥机构的要求,将新的波道参数按照一定加密算法形成特定编码信息,通过北斗短消息发送给网内电台的北斗接收机,解析为电台能够识别的波道参数,触发收发信机在新的参数上工作,从而避开干扰、摆脱窃听,保持通信的安全与畅通.系统设计采用数据分解、交织与重构方式对波道参数进行加密,采用时分多址(Time Division Multiple Access,TDMA)与改进的OLSR路由协议实现网内电台自组网,采用北斗时钟与自身时钟相结合的每日定时(Time-of-Day,TOD)校准策略,并通过导频信号校验方式将通信效果传回指挥机构,使指挥平台能够监控网内电台工作态势,便于系统稳定可靠地工作.试验结果表明,该系统能够在指挥平台控制下,通过北斗短消息传送的信息,实现电台工作参数的自动切换,提高电台抗干扰工作能力. 相似文献
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该文针对北斗卫星定位系统和惯性导航系统提出组合导航卡尔曼滤波定位算法,对组合导航滤波算法的可控性、可观性进行了分析,并用数值分析方法从可观性定义出发分析了各个状态的可观测度,从稳定性的定义出发分析了组合算法的稳定性和渐进稳定性.由于双星时不能对钟差滤波,所以对滤波定位观测模型进行了改进,引入伪距率和惯性器件输出的加速度作为观测量.仿真表明改进方案大大提高了组合定位系统的工作稳定性,抗突发性误差的能力提高了一个数量级,而且双星的情况下可以对钟差滤波. 相似文献
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This paper addresses the problem of high-resolution estimation of a multipath channel delay profile. We propose several improvements to the so-called superresolution pseudo-noise sequence correlation method (SPM) and analyze its performance on time-varying channels. SPM is based on the multiple signal classification (MUSIC) algorithm, which requires decorrelation of the multipath echoes. The proposed improvements enable SPM-based delay estimation in the presence of narrowband interference, and they reduce the necessary transmission window while preserving multipath echo decorrelation. These improvements are analyzed and are applied to underwater acoustic experimental data 相似文献
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Several improvements to T.T. Lee's (1988) multicast switch architecture are described. The improvements make Lee's architecture practical, allowing it to achieve maximum network throughput under worst-case conditions and vastly reducing the amount of memory required for the addressing of multicast cells. These improvements allow multicast to be added to a 256-port switch with 150-Mb/s links at a cost of about two additional chips per port 相似文献
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Wireless Networks - By focusing on dense areas, 802.11ax high-efficiency wireless (HEW) standard offers some improvements over 802.11ac very high throughput (VHT). The HEW improvements are mainly... 相似文献
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Steven D. Millman 《Journal of Electronic Testing》1994,5(2-3):253-261
Until now, it has been thought that the best way to improve quality was to improve yield, that is, to improve the manufacturing process so that fewer defective parts are manufactured. This philosophy has been applied to all areas of manufacturing, from widgets to whalers. One of the tenets of this philosophy is that quality should not be tested in, but should be built in via a well-controlled process that is continuously improving. However, when it comes to semiconductors, significant improvements for a process in order to improve yields can cost millions of dollars. In such a capital intensive industry, where the life of a process is only a few years, such investments are often not in the best economic interests of a semiconductor manufacturer. How, then, can the customers' requirements for quality be met? This article shows that for typical values of yield and test coverage, quality improves faster due to improvements in test coverage than it does for improvements in yield. As a result, testing can be used to achieve improvements in quality at lower costs, and therefore more economically, than improvements in the manufacturing process. 相似文献
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基于中间件技术的HTML业务系统设计与实现 总被引:1,自引:0,他引:1
介绍了欧洲的MHP标准,并在HTML技术方面提出了改进方案。在此方案的基础上设计了一个基于HTML的从前端数据封装到终端数据接收的完整业务系统,并对其应用前景提出了一些看法。 相似文献
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本文提出了一种高速Turbo编译码方法。从算法改进和结构改进技术两方面进行研究,以期解决现有译码算法难以实现高速这一问题。在结构改进技术方面,采用分块思想,将分量编码器分成两块并行处理,速度提高一倍;在算法改进技术方面,一方面针对目前存在的复杂度较低、性能次优的Radix-4 Max-Log-MAP译码算法,通过尺度因子的补偿,得到了译码性能较好的SF-Max-Log-MAP算法。另一方面采用了HDA停止迭代准则,有效地减少了译码时延。 相似文献
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Bouhal A. Jafari M.A. Wen-Biao Han Tong Fang 《Industrial Electronics, IEEE Transactions on》1999,46(2):445-451
This paper discusses the improvements acquired by the introduction of a tracking controller and a look-ahead trajectory-planning policy in part fabrication using the layer manufacturing process. The improvements are quantified not only in terms of tracking and contouring errors, but they are also quantified in terms of overfilled and underfilled areas, thus directly relating the quality of parts fabricated through such a process 相似文献