GPS／Galileo双模捕获引擎的VLSI实现

随着卫星导航进入多星座时代,兼容GPS和Galileo的双模接收机成为目前卫星导航接收机设计的热点。捕获是卫星导航接收机基带信号处理的关键部分之一。本文通过对两种信号捕获算法的分析,提出了一种可以兼容GPS和Galileo信号的捕获引擎的VLSI结构。该结构兼顾了GPS和Galileo的信号特点,可以对GPS信号进行时域并行搜索和对Galileo信号进行时域部分并行搜索。最后给出了该结构各个组成单元的设计方法,在Altera公司的EP2S180FPGA器件上验证通过,并在0．18μm的CMOS工艺下综合,电路规模是3514231平方微米。     

混合二进制偏移载波调制信号快捕算法设计

针对Galileo卫星导航系统的MBOC伪码扩频信号研究基于FPGA的硬件捕获算法设计问题,算法以FFT并行频域捕获为基础,并且采用了平均采样的抽取思想。先利用Matlab进行仿真验证,然后在FPGA实现了该算法,证明了算法的有效性。     

Galileo's Refutation of the Speed‐Distance Law of Fall Rehabilitated

Galileo's refutation of the speed‐distance law of fall in his Two New Sciences is routinely dismissed as a moment of confused argumentation. We urge that Galileo's argument correctly identified why the speed‐distance law is untenable, failing only in its very last step. Using an ingenious combination of scaling and self‐similarity arguments, Galileo found correctly that bodies, falling from rest according to this law, fall all distances in equal times. What he failed to recognize in the last step is that this time is infinite, the result of an exponential dependence of distance on time. Instead, Galileo conflated it with the other motion that satisfies this ‘equal time’ property, instantaneous motion.     

基于混沌扩频CDMA的伽利略卫星定位系统编码技术

在伽利略系统中编码技术日益重要。文章在将混沌扩频技术应用到伽利略系统中后,对系统的信道特性进行了探讨,特别是利用混沌扩频的优秀随机性和正交性对系统进行了信道仿真。仿真结果表明信道衰减小于-40 dB,满足CDMA2000协议规范,从而简化了传统CDMA系统PN码产生的复杂性,统一了信号源和信道编码的混沌序列的使用。这种将混沌扩频CDMA技术代替传统PN序列的方法在伽利略系统中的应用具有实用性和可行性。     

On the inclusion of geographic information systems (GIS) in global navigation satellite systems (GNSS)

The latest innovation of the global navigation satellite systems (GNSS) technologies plays an important role in improving the quality and safety of modern life. Most of the applications evolved from the integration between GNSS, geographical information systems (GIS) and wireless communications and networking (WCN) systems. The wide spread applications that are using these technologies include: the automatic vehicle location (AVL), tracking systems, navigation systems, pedestrian navigation systems, intelligent transportation systems, precise positioning, and emergency callers, among others. The location‐based services (LBS) are possible only by the combination of GNSS, GIS and WCN. The growing need for commercial LBS has forced cellular‐phone and network manufacturers to concentrate on positioning solutions, which are even more precise than the regulatory mandates for positioning of emergency callers and other user services and applications. In this paper, we will present a literature review of the GNSS, the three satellite systems GPS, GLONASS and Galileo, which are aimed to support GNSS services, and a comparison between them and their role in creating a GIS. Copyright © 2006 John Wiley & Sons, Ltd.     

Galileo was Wrong: The Geometrical Design of Masonry Arches

Since antiquity master builders have always used simple geometrical rules for designing arches. Typically, for a certain form, the thickness is a fraction of the span. This is a proportional design independent of the scale: the same ratio thickness/span applies for spans of 10 m or 100 m. Rules of the same kind were also used for more complex problems, such as the design of a buttress for a cross-vault. Galileo attacked this kind of proportional design in his Dialogues. He stated the socalled square-cube law: internal stresses grow linearly with scale and therefore the elements of the structures must become thicker in proportion. This law has been accepted many times uncritically by historians of engineering, who have considered the traditional geometrical design as unscientific and incorrect. In fact, Galileo’s law applies only to strength problems. Stability problems, such as the masonry arch problem, are governed by geometry. Therefore, Galileo was wrong in applying his reasoning to masonry buildings     

一种特殊角三角函数值的快速算法

快速傅立叶变换、兼容GPS/Galileo系统接收机中上下变频以及DDS中都需要变换因子，这些变换因子要求计算 形式角度的三角函数值，提出了一种调整的CORDIC算法，通过仿真该算法在计算这些特殊角度的三角函数值时，不仅节省系统存储空间资源，而且计算效率可以提高50%，是一种行之有效的方法。     

伽利略导航系统若干关键技术分析

分析了目前最新的卫星导航定位系统——伽利略系统所采用的若干关键技术．从卫星轨道布置方式、信号与频率设计方法、伪卫星技术及信号服务等几个方面与GPS进行了对比研究．研究结果表明，Galileo系统具有定位精度高、兼容性好、功能全等优点，在新一代导航系统中具有重要地位．     

关于Pythagoras,Democritus,Plato和Galileo等的不可分割的连续统的存在性的短的证明

自公元前六世纪毕达哥拉斯开始,不少数学家和物理学家,如德谟克利特,柏拉图和伽利略等,都猜想数学中存在不可分割的连续统,一直未获得严格论证。在本文中对此给出一个短的严格证明,用的基础知识较少,又易于鉴别和推广。本文共介绍了四个不可分割的连续统,其中和是标准的,和p是非标准的。存在的实际意义是预示在我们生存的空间的最外层是不可分的巨大的虚空,它有惊人的吞吐能力,其尺寸大到不能以任何一个实数表示,但可以用表示。     

伽利略搜救信号关键参数估计的克拉美—罗界

本文考虑信息位宽的不确定度,研究了伽利略搜救信号信息位宽、到达频率(FOA)和到达时间(TOA)估计的克拉美—罗界(CRB).首先推导了计算Fisher信息矩阵各元素的通用公式,然后推导得到了伽利略搜救信号Fisher 信息矩阵各元素的计算表达式.具体计算时,利用单位冲激函数的性质和Parseval定理,将单位冲激函数...