软件无线电的变频技术研究

随着数字处理技术不断发展,理想软件无线电的最终实现成为可能.本文研究了软件无线电中的关键技术-带通采样下变频技术、数字下变频技术、多速率处理技术.     

软件无线电中前端数字下变频的研究

本文在讨论软件无线电的基本原理、结构、特点以及关键技术的基础上,研究了软件无线电数字前端中的数字下变频(DDC)技术。     

基于FPGA的数字下变频器设计

数字下变频技术是软件无线电的核心技术之一,本文首先介绍了数字下变频器的原理,然后主要讨论了基于FPGA的数字下变频实现方法.FPGA具有大容量,可编程的特性,以及设计和修改方面的灵活性,使得用FPGA来代替专用下变频芯片更加符合软件无线电的思想.     

基于数字下变频器Hsp50214的软件无线电接收机

数字下变频技术在软件无线电中有着广泛的应用，介绍了一种使用数字下变频器Hsp50214实现中频软件无线电接收机的设计。该系统具有从信号的数字化，下变频，同步，到解调的功能，具有一定的实用性。     

软件无线电数字下变频技术研究及FPGA实现

在数字下变频系统实现方案中,输入的模拟中频信号经过高速A/D采样数字化后与数控振荡器NCO(Numerically Controlled Osillator)产生的正交本振信号混频,然后再由抽取滤波模块进行处理,以输出低速的低频或基带信号。本文以软件无线电数字下变频技术为研究对象,参考GSM系统建立数字下变频系统。     

基于多相滤波结构的宽带接收机数字下变频研究

主要介绍了采用软件无线电技术对宽带侦察接收机中频数字信号进行下变频处理的一种方法——基于多相滤波结构的数字下变频处理。在简要说明多相滤波器及下变频器工作原理的基础上,重点介绍了基于多相滤波结构的宽带侦察信号数字下变频处理方法,并给出了采用MATLAB进行仿真的结果。同时,针征对信号处理中对高速测频的要求,介绍了一种基于离散傅立叶变换（DFT）的三次样条插值快速测频方法并进行了仿真。     

基于ADSP-TS101S的高性能中频处理模块设计

结合软件无线电的思想提出了一种宽带数字下变频的设计方案,并从硬件上实现了基于ADSP-TS101S的高性能中频处理模块.     

基于正交混频的数字下变频技术研究

数字下变频(DDC)是软件无线电的关键技术之一,可以将宽带大数据流信号变成窄带低数据流信号,以便后端DSP实时处理;讨论了基于正交混频的数字下变频实现技术.并将它与直接抽取的数字下变频进行对比,显示出其优势,详细给出了数字振荡控制器(NCO)、信号频谱搬移、抽取前的抗混叠滤波器及整数倍抽取的设计方法;通过对一中频信号进行基于正交混频的数字下变频的仿真试验,结果正确解调出了原始信号;表明这种技术简单可行,有较高的实用价值.     

遥测接收机中的数字化技术研究

结合无线电遥测接收机的设计,论述和分析了软件无线电技术中的数字下变频和调频数字解调技术在遥测接收机中的应用.对所设计的方案进行了Matlab仿真,采用Intersil公司的HSP50214芯片、Altera公司的CPLD器件、ISA总线完成了方案的实现.测试表明,该方法使用效果理想.     

基于软件无线电的数字下变频原理和实现

介绍了数字下变频在软件无线电中的原理和应用,以及由Harris公司生产的DDC芯片HSP50016和芯片HSP50214B,并对它们进行了分析。为解决软件无线电在实现中出现的硬件瓶颈提供了解决方案。     

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.