一种WCDMA系统下行信道频偏估计算法及其性能分析

文章在深入研究WCDMA下行链路的信道结构及接收信号处理流程基础上,提出了一种在Rake接收机中,通过对P-CPICH（主公共导频信道）序列两次相关检测实现频偏估计的算法;同时,对该算法主要性能指标进行了分析及仿真,验证了算法的可行性。     

一种新型介质加载的矩形喇叭天线

传统的卫星地面通信系统多采用抛物面天线,但抛物面天线却存在体积大、灵活性差等缺点,而喇叭天线则可以较明显地克服上述不足,但其增益较小、损耗较大。文中设计了一种新型介质加载的矩形喇叭天线,该天线有两层结构:上层为辐射结构,下层为微带-槽耦合馈电结构。辐射结构是中心为矩形喇叭孔的长方体铜板。这种结构的喇叭天线体积适中、活动方便,而且天线增益、反射系数和半功率波瓣宽度相比于传统形式的喇叭天线都有明显改善。     

互联网路由扩展性研究状况分析

Internet的快速发展对路由扩展性造成了巨大的压力。为了Internet能够持续、稳定、快速的发展,互联网技术领域学术界和工业界提出了一些针对Internet的路由扩展性的解决方案。文章基于Internet面临的路由扩展性问题,分析导致问题的原因;在对影响Internet路由扩展性的若干因素进行分析的基础上,重点介绍互联网技术领域学术界和工业界提出的一些典型解决方案;在对Internet路由扩展性问题行总结的基础上,提出未来Internet路由系统的需求。     

Random Network Coding Based Schemes for Perfect Wireless Packet Retransmission Problems in Multiple Channel Networks

Solving WPRTPs (wireless packet retransmission problems) using NC (network coding) is increasingly attracting research efforts. However, no work on NC based schemes for WPRTPs in MCNs (multiple channel networks) has been found. In this paper, RNC (random network coding) based schemes for P-WPRTPs (perfect WPRTPs) in MCNs, denoted as MC-P-WPRTPs (multiple channel perfect WPRTPs), are studied by transforming MC-P-WPRTPs into ILP (integer linear programming) problems. The ILP problems corresponding to MC-P-WPRTPs with four typical configurations are derived. Then the corresponding packet retransmission schedule schemes for MC-P-WPRTPs are proposed based on the solutions to the ILP problems and random network coding. To solve the ILP problems efficiently, an algorithm named as progressively fixing algorithm is proposed which recursively reduce the size of the ILP problem by fixing some of the variables according to some criteria. The criteria are related to the solution to the LP problem obtained by relaxing the integral constraints on the variables in the original ILP problem. Simulation results show that the NC based schemes for MC-P-WPRTPs are effective in saving packet retransmissions. In some situations, NC based schemes can save about 50 % packet retransmissions.     

Robust image hash function using local color features

Conventional image hash functions only exploit luminance components of color images to generate robust hashes and then lead to limited discriminative capacities. In this paper, we propose a robust image hash function for color images, which takes all components of color images into account and achieves good discrimination. Firstly, the proposed hash function re-scales the input image to a fixed size. Secondly, it extracts local color features by converting the RGB color image into HSI and YCbCr color spaces and calculating the block mean and variance from each component of the HSI and YCbCr representations. Finally, it takes the Euclidian distances between the block features and a reference feature as hash values. Experiments are conducted to validate the efficiency of our hash function. Receiver operating characteristics (ROC) curve comparisons with two existing algorithms demonstrate that our hash function outperforms the assessed algorithms in classification performances between perceptual robustness and discriminative capability.     

电视节目安全监测与应急处理系统的设计方案

1概述 为保证广播电视网络和节目播出的安全,对广播电视前端节目播出内容和传输质量进行实时安全监测和应急处理,是广电行业管理的重要任务.为了加强广播电视网络管理和技术防范工作,通过建立广播电视前端节目播出监测与应急处理系统,可以高效、实时地对卫星节目及本地节目进行监测和应急处理,提高对广电网络的监管及处理突发事件的能力和管理水平,确保广电网络播出和传输的安全.     

直升机训练模拟器评分系统的设计与实现

在飞行训练中,需要客观的考核飞行员的飞行技术和飞行质量。依据训练大纲及某型直升机的机载参数记录仪的飞行数据,分析了直升机模拟器评分系统的功能需求,提出了包括模拟飞行分析模块、考核信息管理模块和评分系统维护模块三个功能在内的系统技术方案;详细阐述了模拟飞行分析模块中的关键技术:标准数据库建立和成绩评定原理;最后以起落航线评分为例,证明了评分系统能对飞行成绩及相关飞行信息进行自动管理,并能快速、准确评定飞行训练效果。     

用CS5460和μPD75P3116实现功率和电能计量

本文介绍了用CS5460和μPD75P3116单片机实现功率和电能计量的方法,给出了系统的工作原理、硬件设计、软件设计等.