变换域数字水印处理技术

数字水印是信息安全领域的一项新技术,给出了相对明确的定义。着重分析了变换域数字水印系统的特征及常见攻击,给出了一些相应的对策。最后指出变换域水印的重要问题,即频率的选择问题。     

计算机网络安全系统设计

分析了现代计算机网络所面临的威胁和各种安全问题,同时提出了在设计一个有关网络系统时应该考虑的一些安全问题,如网络安全策略与技术、网络的访问控制、网络数据加密技术、信息隐藏技术等安全问题。     

正交数字上变频器AD9857的使用

介绍数字正交上变频器AD9857的原理、功能和基本使用方法以及如何通过单片机8051实现对它的编程控制。     

Discrete Wavelet Transform: Architectures, Design and Performance Issues

Due to the demand for real time wavelet processors in applications such as video compression [1], Internet communications compression [2], object recognition [3], and numerical analysis, many architectures for the Discrete Wavelet Transform (DWT) systems have been proposed. This paper surveys the different approaches to designing DWT architectures. The types of architectures depend on whether the application is 1-D, 2-D, or 3-D, as well as the style of architecture: systolic, semi-systolic, folded, digit-serial, etc. This paper presents an overview and evaluation of the architectures based on the criteria of latency, control, area, memory, and number of multipliers and adders. This paper will give the reader an indication of the advantages and disadvantages of each design.     

飞行目标3维姿态测量的新方法

针对传统光测方法通常用于测量目标的点运动轨迹,而难以获得目标的3维姿态参数的情况,提出用数字图像处理手段,对目标图像建立特征点,结合特定的算法,得出目标的俯仰角、偏航角、滚动角、漂移量等3维参数,从而获取更多的目标姿态参数的新方法。     

Implementation of RNS-Based Distributed Arithmetic Discrete Wavelet Transform Architectures Using Field-Programmable Logic

Currently there are design barriers inhibiting the implementation of high-precision digital signal processing (DSP) objects with field programmable logic (FPL) devices. This paper explores overcoming these barriers by fusing together the popular distributed arithmetic (DA) method with the residue number system (RNS) for use in FPL-centric designs. The new design paradigm is studied in the context of a high-performance filter bank and a discrete wavelet transform (DWT). The proposed design paradigm is facilitated by a new RNS accumulator structure based on a carry save adder (CSA). The reported methodology also introduces a polyphase filter structure that results in a reduced look-up table (LUT) budget. The 2C-DA and RNS-DA are compared, in the context of a FPL implementation strategy, using a discrete wavelet transform (DWT) filter bank as a common design theme. The results show that the RNS-DA, compared to a traditional 2C-DA design, enjoys a performance advantage that increases with precision (wordlength).     

珠海台网络硬盘多频道数字播控系统

叙述了以视频服务器为中心构建的网络化多频道自动播出系统的实践、见解和系统的特点。该系统着重考虑了视频服务器选型、系统可靠性、网络化控制及监控、信号共享等问题；同时，实现了多路同时上载、多路边播边上载，以及自动延时播出等功能。     

数字电视的条件接收系统

数字电视的兴起使人们能够欣赏到高质量的电视节目,伴随数字电视的成熟,条件接收系统(CAS)得到很好的发展。主要介绍数字电视条件接收系统相关技术的发展、基本功能、安全机制、工作原理及其安全性要求。     

一种基于数字电路的纳秒级脉冲产生方法

介绍了超宽带无线电的基本概念和技术特点,对几种典型的超宽带窄脉冲产生方法进行了描述和比较,提出了一种采用数字电路实现超宽带纳秒级窄脉冲的新方法,叙述了电路的基本原理和核心器件的主要性能,给出了电路结构,并对试验电路进行了测试。最后给出了测试结果并对测试结果进行了分析,得出了相关的结论。     

数字下变频器GC1012B原理及配置方法

数字下变频技术是软件无线电的一项核心技术,其性能的好坏直接影响数字接收机的精度。GC1012B是美国TI公司推出的新型数字下变频器。文中从GC1012B的结构特点和内部功能框图出发,分析其工作原理,并介绍GC1012B几个主要寄存器的配置方法,从而实现对频率、滤波模式、增益大小等参数的设置。最后给出了一个具体配置实例作为参考。