数字集群通信在中国民航空管系统的发展应用研究

文章介绍了国内外以及中国民航数字集群发展及应用情况,提出适应中国民航系统数字集群通信发展的思路,认为应结合民航系统的行业特点找准数字集群通信的定位,在此基础上积极发展民航空管数字集群通信市场,更好地发挥数字集群系统的优势。     

TETRA数字集群在地铁无线调度系统中的应用

本文首先介绍了TETRA数字集群无线通信系统的技术特点,同时结合西安地铁二号线的实际情况,重点阐述西安地铁二号线无线调度通信系统的组成,信号覆盖实现方式及实现功能。     

集群式并行高性能运算技术分析及其在数字电影拷贝制作系统中的应用

高性能计算机,尤其是集群式计算系统在近些年开始逐步被应用在并行渲染计算领域.北京电影学院数字媒体技术研究所在进行数字电影拷贝制作系统的研究时,运算并行化是其中重要的一个方面.本文对于集群运算的特点进行了简单介绍,对于数字电影拷贝中的运算特点进行了分析,阐述了对于并行数字电影拷贝制作系统实现的原理与方法,并针对所实现的系统进行了监视与分析,对今后如何更好的发展并行数字电影拷贝制作系统提出了展望.     

嵌入式系统在数字电影中的应用

本文介绍了数字电影流动放映采用SIGMA DESIGN 862x或863x系列嵌入式系统作为解码平台播放器的解码、解密以及与数字投影机连接专用控制协议,指出嵌入式平台的低成本、稳定性是PC平台所不具备的.     

摩托罗拉系统连续赢得机场TETRA订单

摩托罗拉系统（Motorola Solutions）凭借其先进的TETRA数字集群无线通信系统于2010年12月至2011年6月期间连续赢得国内七大主要城市机场800MHzTETRA数字集群无线通信系统订单,包括沈阳桃仙国际机场、昆明巫家坝国际机场、南昌昌北国际机场、珠海三灶机场、杭州萧山国际机场、重庆江北国际机场及贵阳龙洞堡国际机场。此次系统部署使七家机场从现有的模拟集群通信系统成功升级到TETRA数字集群通信系统。     

模拟电视的数字亮色分离实现方法

传统的模拟电视如果采用模拟电路的方式来实现亮色分离,成本和解码质量都不能令人满意。主要讨论如何用数字方式实现复合模拟电视信号(CVBS)的亮色分离。该数字解码器可以提供比较好的图像解码效果,并可与ADC一起配合,实现高度集成的SOC芯片。     

TETRA数字集群通信系统在广州地铁中的应用

介绍了新一代数字集群通信系统TETRA系统的标准和功能特点,对广州地铁的无线集群通信系统的网络结构及应用做了分析说明。     

一种新的高清数字电影播放系统的高速缓存和音视频同步设计

基于FPGA和专用解码芯片结构,实现了一种符合DCI规范的2K高清数字电影播放系统.针对高清数字电影码流数据量大、传输速率高的特点,设计了一种采用乒乓结构和基于目录表的动态内存管理策略的高性能缓存系统,以及一种基于高速缓存和帧查找表的音视频同步方法,整套系统简单高效,便于VLSI硬件实现.实验结果表明,此系统可以流畅播放350Mbps码率的数字电影,并且连续播放3个小时,音视频失同步可控制在20ms之内,满足数字电影规范的要求.     

基于NiosII的LFM时延差编码解码器

提出一种LFM信号时延差编码的解码检测系统设计方案,在单片芯片上实现了直接数字下变频器（DDC）,复相关器以及基于NiosII软核处理器的软件系统,完成了片上实时LFM信号检测接收系统的设计,充分发挥了FPGA高速并行处理和C语言灵活、易升级维护的特点,实现了系统软硬件的完美结合。     

OpenVPX在数字集群通信处理平台中的应用

OpenVPX总线标准的推出,奠定了新一代专网通信处理平台的发展方向。数字集群通信系统作为专网通信中的代表,一直沿用着传统的自定义总线架构,这些架构普遍存在传输带宽低,实时性差,通用性低,系统灵活性差等缺点。文章针对数字集群系统架构提出了一种基于OpenVPX总线标准的数字集群通信处理平台。处理平台大幅度的提高了传输带宽,单通道传输速率可达6.25Gbps;系统兼容性高,不同厂家间系统可实现模块间交叉互换;总线分离,根据系统中总线功能性差异细分总线类型;设计灵活性强,可针对不同系统需求进行多种拓扑结构设计。     

数字集群系统离散接入主控信道的性能分析和评价

分析了数字集群系统的离散接入原理和性能。根据系统的初始呼叫强度和离散接入帧长推导出系统主控信道总的业务量、接入时延及每时隙的平均接入个数，并分析了离散接入帧长对上述参数的影响。所得结论对于数字集群系统的开发具有实际意义。     

Dynamic parameter estimation of a second-order system to a stepfunction

A method of characterizing the time-domain response of a second-order system to step function by dynamic parameter estimation is presented. The method uses digitized samples of the input signal and does not require a priori information about step function amplitude, damping ratio, and angular natural frequency. Mathematical development of the algorithm is presented and its accuracy is illustrated in digital simulation studied     

The signaling efficiency of group mobility management in Cellular IP

Grouping is usually beneficial from a system efficiency perspective, e.g., trunking efficiency achieved by sharing a common channel among users. In this article, the signaling cost of mobility management in Cellular IP is numerically analyzed. In addition, it is shown analytically that by organizing mobile hosts having the same mobility pattern into a group, the signaling cost of mobility management in Cellular IP can be effectively reduced. This is because location information of the group can often be refreshed by data packets sent by group members. As a result, the reduction is more significant for a larger number of busy mobile hosts in the group.     

数学形态学在图像处理与分析中的应用及展望

介绍了一种新型的图像处理和分析理论--数学形态学的基本运算方法和应用。由于对数字影像内定向时框标的识别与定位是从数字影像提取数据的关键步骤，框标中心坐标确定的准确度将直接关系到所提取数据信息的精度。依据数学形态学原理，根据十字框标自身的几何和拓扑特征，构造了系列形态变换模型，详细叙述了使用该模型自动识别数字影像框标的具体方法和步骤。最后对数学形态学今后的研究、发展进行了展望。     

Digital processing of electronic speckle pattern interferometry addition fringes

A digital image-processing method for analyzing double-pulsed electronic speckle pattern interferometry addition fringes is described. The procedure consists of three steps, forming a combination particularly suited to addressing some important practical limitations of the measurement system. In the first step it is shown that in certain cases fringe visibility may be enhanced by subtraction of a reference interferogram, so that a pattern with a quality similar to that of a subtraction one is obtained. In the second step noise is reduced by the application of a spectral subtraction image-restoration method. The third step concerns the calculation of the wrapped phase by means of a Fourier transform method with bandpass filtering. Preliminary experimental results that illustrate the performance of this approach are presented.     

基于轴角转换的火炮伺服测试技术

针对现代火炮伺服电机通常都采用自整角机的特点,提出基于轴角转换的火炮伺服测试技术。由微处理器和数字-自整角机转换器组成伺服测试系统,通过微处理器装定数字量角度信息,由数字-自整角机转换器转换为粗精双速模拟量角度信息,然后传送给火炮伺服。由伺服带动炮身做相应的角度旋转,然后比较实际值和理论值,统计分析火炮伺服的精度、灵敏度和响应速度。该系统可以做包括阶跃、方波、步进、等速、正弦等多种测试运动,并且具有结构简单、操作灵活、可靠性高等优点,对采用自整角机做伺服电机的角度控制系统具有很好的示范作用。     

A precise dc motor speed control using deadbeat response technique

Abstract

An approach to the design of a simple and low‐cost digital system for precise DC motor speed control is introduced. A microcomputer is employed to measure the motor speed, implement the control algorithm, and generate the controlling signal. The motor speed is measured in terms of feedback pulse width. The control algorithm is a digital PI controller with specific parameters such that the system has deadbeat response to step input. The controlling signal is converted by a digital circuit to specify the conducting period for the SCRs of a three‐phase full‐wave controlled rectifier which provides the DC source for the DC motor. The interface between the microcomputer and the outside world needs only three lines. The experiment on a 2 HP separately excited DC motor shows that the speed is regulated within 0.05% and the settling time is about 1.5 seconds under 25% load disturbance for some specific speeds.     

数字化电容层析成像系统

基于电容敏感原理设计的数字化电容层析成像（ECT）系统，利用有限元法，分析了阵列电极结构对敏感场分布的影响，通过优化设计和仿真试验，改善了敏感场分布的均匀性；构建了以数字信号处理器（DSP）为核心、现场可编程门阵列（眦）协同工作的12电极的数字化ECT系统，提出了由离线预迭代和在线一步成像所构成的新的图像重建算法——预迭代法，其成像速度及精度均明显得到提高。     

英国可再生能源技术管理与开发调研

介绍了硅微谐振器系统的工作原理，重点给出了一种基于新型的DDS器件AD9954的智能谐振系统设计与实现。详细分析了AD9954作为智能精密驱动源的粗细搜索两种阶段工作流程并给出与DSP器件的数字接口技术。结合实验数据和扫频曲线，得出在不同真空度环境下谐振器的两种扫频结果，并对谐振系统的工作情况给予评价。     

New Method for Measuring Statistical Distributions of Partial Discharge Pulses

A new digital detection system is described for measuring pulsating partial discharges (PDs). The PD detection system can continuously record all PD pulses that occur over extended periods of time, with a minimum inter-pulse time separation of 6 μs and a vertical amplitude resolution of 12 bits. Earlier PD detection systems detected PD pulse amplitude and time using complex custom-designed hardware while the present system continuously records the complete electrical waveform that carries the PD pulses using a commercial data acquisition board and extracts, in real time, the time and amplitude information of all PD pulses in software. The current approach considerably reduces the development and maintenance cost of the PD detection system, significantly increases the system portability, and may prove to be a crucial step for transferring the digital PD detection and analysis technology developed in laboratories to industry. The features of the new system are illustrated by the study of dc-excited PD pulses occurring in a point-to-plane gap in air. A new surface-mediated burst mode of PDs is discovered in which a PD pulse has a certain probability to induce another pulse. The probability is determined for several gap voltages and is found to vary strongly with the applied voltage.