ALTBOC调制信号功率谱推导新方法

伽利略导航系统将在E5频段发射交替二元偏置载波(Alternate Binary Offset Carrier,ALTBOC)信号,但国内外学者对其特性的研究还很不充分。基于随机信号分析理论,在对Galileo ALTBOC(15,10)信号各分量正交性证明基础上,提出采用多进制符号编码调制信号功率谱和正交信号功率谱公式推导Galileo ALTBOC信号的功率谱的新方法,并将其与传统双向偏移QPSK-R(10)信号功率谱近似算法进行比对,ALTBOC功率谱密度与双向偏移QPSK-R(10)功率谱密度最大差0.9 dB。     

BOC调制导航信号关键技术研究

BOC调制作为一种导航信号体制,具有良好的抗多径和抗干扰性能,同时实现共用载波频率条件下的频谱分离。与BPSK调制信号相比,BOC调制信号具有多径误差小、码跟踪热噪声误差小的优点。通过对BOC调制技术和合路方式的深入分析,给出了各种BOC调制的自相关和功率谱函数,以及各种合路方式的分析比较。通过仿真验证了BOC信号的码跟踪性能和抗多径性能的优越性。     

Unambiguous S‐curve shaping technique for multipath mitigation in Global Navigation Satellite Systems alternative binary offset carrier signals

Global Navigation Satellite Systems positioning accuracy indoor and urban canyons environments are greatly affected by multipath because of distortions in its autocorrelation function. In this paper, we propose a new multipath mitigation technique based on the concept of S‐curve shaping for the new alternative binary offset carrier (AltBOC)‐modulated signals, which will most likely be used in both European Galileo system and Chinese Compass system. The definition of an optimum S‐curve is employed to reduce the false lock points and to improve the multipath mitigation capability via determining the shape of the local code tracking reference function. The structure of the proposed code tracking loop for AltBOC signals is quite simple and only requires one complex correlator. Results demonstrate that the proposed technique provides superior multipath mitigation performance compared with the conventional receiver correlation techniques and removes the ambiguity completely. Copyright © 2012 John Wiley & Sons, Ltd.     

Excessive Resolution: From Digital Streamlining to Computational Complexity

Is the term ‘ornament’ set to become redundant in architecture? With the sinuous lines produced by CNC milling machines giving way to the ever more weirdly figural products of algorithmically controlled 3D printing, decoration is increasingly an integral part of form, rather than supplementary to it. Mario Carpo – Reyner Banham Professor of Architectural Theory and History at the Bartlett School of Architecture, University College London – investigates this voxellisation, and how it drives architecture beyond human comprehension.     

适用于 SBAS和 Galileo 卫星导航接收机的 Viterbi 译码器实现

设计并实现了一种适用于SBAS和Galileo卫星导航系统的（2,1,7）卷积码的Viterbi译码器．由于卫星导航系统中的数据率不高,采用串行结构实现 Viterbi译码器,并且多通道复用同一译码器,以节省电路面积．此外,采用改进的加比选单元并通过寄存器交换法对幸存路径进行管理,以进一步优化电路结构．为了减少RA M 的使用,利用同址更新技术将路径度量累加值和幸存路径存储至RAM ．译码电路通过FPGA验证,采用SMIC65 nm工艺库进行综合,该译码器逻辑电路的面积为4738μm2．     

论伽利略的科学方法

介绍了伽利略所开创的数学—实验科学方法的意义,肯定了伽利略在科学史上的地位.     

多卫星系统组合导航的可用性分析

在航空应用中,多卫星导航系统组合导航是未来的发展趋势,可用性是航空应用的主要性能要求之一。但是在截止角增大时,GPS单系统的可用性却达不到航空性能标准。针对该问题,对GPS/Galileo/BD组合系统在中国境内的可用性进行仿真分析,与GPS单系统相比,组合系统的可用性相对单系统有所提高,且截止角较大时,仍能达到可用性要求。