一种用于调制识别的盲码元定时估计算法

针对通信信号调制识别中的同步分类问题提出一种盲码元定时估计算法,对于调制方式未知的信号,可以估计未知信号的定时同步,得到最佳采样点信息,实现数字信号的同步分类。仿真结果表明本文的算法对于各种信号具有良好的同步效果。     

Effect of broadcast and precise ephemerides on estimates of the frequency stability of GPS Navstar clocks

Frequency stability analysis of on-orbit Navstar clocks is performed by the Naval Research Laboratory using both the broadcast and the precise post-processed ephemerides. The phase offset between the Navstar clock and the reference clock is computed from pseudorange measurements obtained by dual-frequency GPS receivers at the five GPS monitor sites and at the U.S. Naval Observatory precise-time site. The broadcast ephemerides are generated at the GPS master control station by a Kalman filter using data collected from the five GPS monitor stations. The precise post-processed ephemerides are generated by the Defense Mapping Agency (DMA) using data collected from the GPS monitor sites and from five additional DMA monitor sites. In this paper the frequency stability is estimated for two Navstar caesium clocks–a Block I caesium clock (Navstar 9) and a Block II caesium clock (Navstar 23)–using both the broadcast and the precise ephemerides. A significant improvement in the estimate of the frequency stability of the Block II clocks has been achieved using the precise ephemeris.     

AGPS全球定位系统中辅助信息传输协议RRLP的研究

全球定位系统的应用越来越广,已经成为人们日常生活中不可缺少的一部分,在移动通讯、交通以及汽车领域当中,定位显得尤为重要.不久的将来,全球定位系统的发展将不可限量.文章首先介绍了GPS的工作原理,并指出了AGPS与之的区别,接着根据OMA所提出的SUPL标准简要阐述了APGS定位的流程,最后重点讲解了用于辅助信息传输的RRLP协议.     

SDH光纤传输系统的信道处理及接收定时特性

本文从ＳＤＨ信号流的帧结构和ＳＤＨ光传输系统采用的简单扰码的线路码型出发，分析了系统对信道的要求，提出了对通道带宽、定时恢复、对信号图案抖动抑制等有关系统设备设计参数的计算方法。     

省级远程视频监控系统的设计方案

提出了一个安全生产监督管理远程视频监控系统的设计方案,是采用GIS、GPS、流媒体、IP组播等技术手段构架的网络远程视频监控系统,该设计方案的目标是要达到对一个省的安全生产进行方便高效的监督管理.     

Visteon为中国用户提供量身定制GPS产品

美国汽车零部件供应商伟世通(Visteon)近日发布了其新款集成式导航产品。据悉,整合了数字音响系统、DVD、导航系统、先进用户友好人机界面和空调控制系统等功能的该导航产品,是首款     

GPS系统在交通运营管理中的应用

在国家智能交通系统（ITS）的发展战略和产业化方向的指引下,GPS技术在ITS的发展中得到广泛的应用与发展,随着交通运输规模的不断扩大,它在交通运营中的应用也得到广泛地推广。本文着重介绍了GPS系统在交通运输中的应用,包括在车辆交通管理,军事交通、奥运车辆监控等方面的作用,最后做了总结和展望。     

Gate-level dual-threshold static power optimization methodology (GDSPOM) using path-based static timing analysis (STA) technique for SOC application

This paper describes a novel gate-level dual-threshold static power optimization methodology (GDSPOM), which is based on the static timing analysis (STA) technique for designing high-speed low-power SOC applications using 90 nm multi-threshold complementory metal oxide semiconductor (MTCMOS) technology. The cell libraries come in fixed threshold—high V_th for good standby power and low V_th for high speed. Based on this optimization technique using two cell libraries with different threshold voltages, a 16-bit multiplier using the dual-threshold cells meeting the speed requirement has been designed to have a 50% less leakage power consumption when compared to the one using only the low-threshold cell library.     

一种带改进“当前”统计模型的GPS/DR车辆组合定位系统

文中分析了"当前"统计模型在GPS/DR车辆组合定位实际应用中的问题,基于"当前"统计模型原理提出一种改进的"当前"统计模型,并将其应用于GPS/DR组合定位系统的数据融合中.实地跑车数据验证表明:使用该算法的定位系统无需任何参数的预先设定,即可实现对系统方差的自适应调整,对车辆的各种运动状态进行准确跟踪.