Galileo E1-B/C仿真信号合成通道设计

针对Galileo信号合成中超长测距码生成以及功率控制的硬件实现难题,设计了双口RAM的重载查表式测距码生成器,同时,基于CBOC副载波特性,提出了比例因子功率控制的优化方法,并进行了仿真实验对比.结果表明:该方法设计的信号合成通道极大地节约了内存空间和硬件乘法器资源,单片FPGA内信号合成通道的集成数量扩大1倍以上,...     

The New Science of Form-Searching

New technologies, by definition, change fast, as does our cultural awareness of our use of them. Mario Carpo , Reyner Banham Professor of Architectural History and Theory at the Bartlett School of Architecture, University College London (UCL), explains how in the course of the last few years much of our discourse on new technologies has been driven by an unexpected and, in many ways, inexplicable development: the availability of almost unlimited data storage and data-processing capabilities at ever-decreasing - and often almost negligible - costs. As digitally intelligent designers and structural engineers have not failed to notice, this simple, almost banal technical development has the potential to disrupt the way we design and calculate almost everything.     

Galileo/GPS组合观测值在RTK定位中的应用研究

随着Galileo系统的建成和GPS的现代化,RTK将会得到大大的改善。本文主要阐述了RTK的原理、主要的误差源和存在的局限性,主要研究了GPS的L2载波和Galileo系统的4个频率的载波之间的双差组合,并得出了几组有效组合,即波长较大的组合,以加快利用RTK定位时的模糊度的固定速度,从而提高RTK的定位质量。     

"伽利略"卫星导航系统综述

“伽利略”计划是欧盟为了打破美国的GPS在卫星导航定位这一领域的垄断而启动的迄今为止欧洲将要开发的最重要的航天计划。无论从技术角度、经济角度、还是从战略角度出发,该计划都具有极高的研究价值。文章重点围绕“伽利略”系统的计划、体系结构、系统服务方式及中国加入“伽利略”卫星导航系统的重大意义进行了论述。     

Baroque Parameters

Andrew Saunders describes how students on Rensselaer School of Architecture's Rome programme were encouraged to explore the geometry and mathematics that underlie the architecture of the Baroque through parametric design. Copyright © 2009 John Wiley & Sons, Ltd.     

伽利略导航卫星E1 B伪码跟踪技术研究

Galileo系统的BOC信号有更小的跟踪抖动和更好的抗多径性能,BOC信号自相关函数具有的多峰性使跟踪具有很大的难度,跟踪时容易误锁在边峰上。为了解决这个问题,利用Fante提出的自相关函数线性化算法推导了一组参数,仿真结果表明该组参数的归一化鉴别器输出的码片误差在-1到1之间具有线性特征,最后介绍利用此方法参数实现的接收机。     

伽利略卫星通信系统的C/A码的编码与捕获方法研究

伽利略卫星通信系统中主要由C／A码、P码、M码来实现导航定位,其中关键的就是C／A码。相对P码、M码来说,C／A码精度较低且编码格式公开,而面向民用时,P码格式还未公开,且对P码进行捕获时也是建立在先捕获C／A码上的,因此主要针对C／A码进行了仿真研究。在C／A码生成和调制仿真的基础上,进行了．C／A码捕获的传统自相关方法研究,从算法的角度提出一种基于FFT的C／A码快捕方案的改进,减少了捕获的计算时间。并在加噪情况下对捕获方法进行仿真,进一步证实了改进方法的可行性,为P码的捕获研究提供了有效参考依据。     

4种全球定位系统的现代化及其坐标转化

基于卫星导航定位技术在国防和国民经济各领域中应用的重要性,世界主要国家或联盟都在积极谋划建立或完善自主的导航定位系统,其中包括美国的GPS、俄罗斯的GLONASS、欧盟的Galileo和中国的COMPASS-2。介绍4种导航定位系统的系统组成、运行状况及其应用特点;对于各导航系统组合定位需要解决的统一时空基准问题,给出各空间坐标系统转换的计算公式。     

Combined Galileo/GPS architecture for enhanced sensitivity reception

Several new requirements and challenges are introduced with the transition of traditional navigation applications towards location-based services (LBSs). This paper introduces the HIGAPS receiver concept. Aim of the HIGAPS project is to develop the concept for a combined Galileo/GPS receiver that is specially tailored for LBSs, E-911, and other consumer market applications. After a brief overview of the receiver, the partitioning into analog hardware, digital hardware, and software is outlined. The architecture of the combined Galileo/GPS RF front-end is presented in low-IF topology. The digital baseband presents a highly parallel correlation architecture for combined Galileo/GPS reception, allowing fast times to fix for extended dwell times. Parallel digital signal processing combined with aiding data allows single-shot measurements particularly designed for LBSs. Differential correlation further improves the reception sensitivity. The coherently integrated predetection samples are thereby multiplied with the conjugated complex previous predetection samples.     

The Conception of Ramparts in the Sixteenth Century: Architecture, “Mathematics”, and Urban Design

The discovery of gunpowder and its military applications caused a revolution in the common systems of defence, which had not changed substantially from the Roman period. New methods of laying out urban defences in the second half of the sixteenth century was the product of a continuous response to the evolution of fire arms and their increasing power. The goal of this article is to explain these assertions, analysing in detail the factors that characterized the “science of fortification” in the sixteenth century.