自适应均衡器的FPGA实现

在无线通信系统中,由于多径效应的干扰导致信号在传输过程中不可避免地产生码间干扰,因此必须在接收端增加均衡器,以消除码间干扰,提高传输质量。该自适应均衡器设计以FPGA为设计平台,使用自上而下的模块化的设计方法,利用StratixⅡ系列EP1C20F324C6芯片,采用横向滤波器结构,设计并行结构的8阶复数滤波器。最后在QuartusⅡ中进行仿真与综合,结果显示I、Q两路误差信号趋于零,从而实现自适应均衡,降低误码率。     

一种高速通信中的模拟自适应均衡器设计

由于LVDS传输线在高速数据传输中存在着码间干扰,限制了传输数率和传输距离.因此引入均衡器来补偿数据的高频损耗就变得尤其重要.鉴于模拟自适应均衡器的诸多优点,设计一个基于CMOS工艺的高速模拟自适应均衡器.采用了TSMC 0.25μm CMOS工艺实现,能够很好的均衡传输数率为2Gbps的数据信号.     

一种联合盲均衡算法

为克服数字基带信号在通过非屏蔽五类双绞线时产生的严重码间干扰(ISI),常采用自适应均衡技术来减小码间干扰,大大降低接收端信号的误码率.最小均方误差(LMS)算法能有效降低码间干扰,但需要训练序列,因此影响传输效率.基于判决引导的最小均方误差(DDLMS)算法不需要训练序列,但在眼图未睁开的情况下,可能出现误判,甚至引...     

数字基带传输系统码间干扰的研究

数字基带传输具有非常重要的研究及应用的的意义,而码间干扰是一种常见现象,它对该系统具有很大的影响,因此研究码间干扰非常重要。首先通过Matlab搭建数字基带传输系统,然后通过噪声和码元速率与系统带宽不匹配来引入码间干扰,最后对这两种方法引起的码间干扰进行了研究和仿真分析。     

CIPS 基带传输信号的码形向题初探

数据通信系统的设计中,基带传输信号的码形选择,无论对基带传输系统,还是频带传输系统,都直接影响数据传输的效果。本文主要介绍几种常见的基带传输信号的码形及特点,着重讨论一种被计算机局部地区网采用的传输码形——Manchester 码,最后给出用小规模集成电路实现的可与支持HDLC 规程芯片相连的编码与解码器。     

自适应判决反馈均衡器算法研究

自适应均衡是现代通信中广泛采用的消除码间干扰的一种方法。为了适应高速数据传输的要求，达到在非线性畸变信道上较好的抗噪声性能，可采用非线性自适应均衡器-判决反馈均衡器（DFE），实现算法一般是以随机梯度下降（SGD）算法为基础的RLS、CMA和LMS及LMS改进算法，由计算机仿真结果可知：在实际工程应用中，判决反馈均衡器的效果良好，特别是LMS改进算法效果更佳。     

一种在多径信道下LDPC码的解码设计

本文首先简单介绍了基带编码调制的LDPC系统与信道模型,接着设计了一种适合应用在多径信道下的自适应均衡器;然后,对LDPC码以及编译码模块进行了构造;最后,本文对所提出的由自适应均衡滤波器和LDPC解码器组成的自适应LDPC译码系统的误比特率（BER）性能进行了仿真,仿真结果表明新的译码系统可以解决在多径信道下BER性能较差的问题。     

基于SoC的抗窄带干扰和自适应门限的基带捕获IP设计

在卫星扩频通信中,信号的捕获跟踪模块是整个基带处理SoC设计的核心。本文针对影响基带处理性能的窄带干扰和固定门限无法适应移动信号的快衰落变化这两个突出因素,提出解决方案,给出抑制窄带干扰自适应能量判决门限的滤波和双门限自适应调整PN码捕获的改进IP。采用SoC设计方法使IP快速融合到整个系统并实现了设计的可重用性,并结合ARM公司的Integrator/AP ASIC Development Board实现整个SoC基带处理器的协调工作,验证了设计的正确性和稳健性。     

基于仿射投影算法的信道均衡器研究

为了克服信号传输中码间干扰影响,改善通信质量,研究了基于仿射投影算法(APA)的信道均衡系统.设计APA均衡器的关键是确定步长因子和滤波器长度,使系统的误码率最低.首先根据其性能仿真曲线可以得到一组最优的参数值,然后构建SIMULINK仿真平台进行验证,并和LMS及NLMS均衡器作对比.结果表明APA均衡器是有效的,并能在信道失真较严重的场合保持一定的性能.     

基于非平稳时频分析的无线网络信道均衡算法

在无线网络数据通信中,由于阵元码间干扰导致信道具有非平稳特性,产生信道失衡效应,需要进行信道均衡设计,提高无线网络的数据传输性能.传统方法采用Hilbert变换扩频方法进行通信信道均衡,通过Hilbert变换使离散数据解析化,由于信道多径扩展导致码间干扰,为了提高信道均衡效果,提出一种基于非平稳时频分析的无线网络信道均衡算法.构建无线网络数据传输的空间多径信道模型,采用时频分析方法进行通信信号码间干扰抑制处理,采用提取的时频特征对通信信道进行正交频分复用分解,采用时频特征分析方法,对相位偏移进行空间码元重组,去掉路径相移偏量,实现信道均衡.仿真结果表明,采用该算法具有较好的信道均衡性能,能有效抑制通信信道的码间干扰,降低无线网络数据通信的误比特率,改善通信质量.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.