光电耦合器在A／D采集系统中的集团的研究

光电耦合器具有很强的抗干扰能力，在微机控制的数据采集系统中，光电耦合器所处的位置对系统的性能有直接的影响。本文阐述了光电耦合器位于A／D转换器之后和之前两种方案的特点、存在的问题及解决问题的办法；最后指出，为了适应A／D顺和CPU等功能模块集成在一块芯片上这一微处理机的现状和发展趋势，应该认真研究和更多地采用将光电耦合器放在A／D转换器之前这种方案。     

电源

飞兆推出CMR光电耦合器解决方案 飞兆半导体（Fairchild）推出共模抑制（CMR）光电耦合器解决方案FOD3120和FOD3150。这两种产品是输出电流分别为2．5A和1A的栅极驱动光电耦合器,即使在最噪杂的工业环境中,也能够轻易驱动1200V／20AIGBT和MOSFET。     

铂电阻测温电路的线性化设计方法

介绍一种基于A／D转换原理的铂电阻测温的非线性校正方法，分析了铂电阻线性测温的原理，并给出了A／D转换器7135与单片机89C51接口电路及试验数据。     

多通道实时数据采集系统的设计和实现

描述了一个具有高吞吐量的实时数据采集系统设计和实现方案，本系统由1台PC机、1台89C51单片机，1个高速采样A／D转换器和双端口FIFO缓冲器构成。     

医疗数字图像系统控制器研究

设计了一种医疗数字图像系统控制器,该控制器基于Atmel单片机AT89C52,结合光电耦合器、D／A等多种集成器件完成对医疗数字图像系统中电平信号的采集、放大和转换,对影像部分和图像处理部分的驱动和控制。文章简要介绍了医疗数字图像系统的原理和结构,介绍了数字控制器的作用和工作原理,详细阐述了控制器的硬件结构及实现方案,并对软件结构进行了阐述。经运行测试证实,该控制器系统结构简单,性能可靠,易于维护,性能价格比高。     

DSP和高速摄象机的接口

高速光电二极管阵列摄象机在光电信息处理方面,特别是在自适应光学领域中,得到了广泛的应用。摄象机输出的视频信号的A/D 转换技术以及摄象机和DSP、图象存储器之间的接口技术是其关键。本文应用DMA 控制技术实现了摄象机和DSP、图象存储器之间的接口,A/D 转换由MB9000数字格式器来完成,DMA 控制器由中小规模集成电路组成。     

采用分时开关改善串并型A/D转换器的性能

本文针对通常的串并型A/D转换器所存在的零点漂移等问题提出了一种方案,即在各串型级之前插入分时开关的办法;并用实验证明了这种方法对于克服整个装置的零点漂移、提高转换速率,抑制尖峰噪声和防止寄生振荡等是十分有效的。     

用存储器映射方法设计数字直流电压表

介绍了用A／D转换器和EPROM存储器设计数字式电压表的方法。     

8098单片机在雷电定位系统中的应用

介绍了8098单片机在新一代雷电定位系统数据采集模块中的应用，并详细介绍了其A／D转换器和高速输出口的软硬件设计。     

光电耦合器的实用技巧

从光电耦合器的基本结构和性能特点出发，针对采用光电耦合器进行抗干扰设计中遇到的非线性、响应速度及功率接口三个方面的问题，提出了相应的电路设计方案，介绍了不同类型的光电耦合器及其应用实例。     

Design considerations for electromagnetic couplers in contactless power transmission systems for deep-sea applications

In underwater applications of contactless power transmission （CLPT） systems, high pressure and noncoaxial operations will change the parameters of electromagnetic （EM） couplers. As a result, the system will divert from its optimum performance. Using a reluctance modeling method, we investigated the gap effects on the EM coupler in deep-sea environment. Calculations and measurements were performed to analyze the influence of high pressure and noncoaxial alignments on the coupler. It was shown that it is useful to set a relatively large gap between cores to reduce the influence of pressure. Experiments were carried out to verify the transferring capacity of the designed coupler and system for a fixed frequency. The results showed that an EM coupler with a large gap can serve a stable and efficient power transmission for the CLPT system. The designed system can transfer more than 400 W electrical power with a 2-mm gap in the EM coupler, and the efficiency was up to 90% coaxially and 87% non-coaxially in 40 MPa salt water. Finally, a mechanical layout of a 400 W EM coupler for the underwater application in 4000-m deep sea was proposed.     

Data streaming in telepresence environments

In this paper, we discuss data transmission in telepresence environments for collaborative virtual reality applications. We analyze data streams in the context of networked virtual environments and classify them according to their traffic characteristics. Special emphasis is put on geometry-enhanced (3D) video. We review architectures for real-time 3D video pipelines and derive theoretical bounds on the minimal system latency as a function of the transmission and processing delays. Furthermore, we discuss bandwidth issues of differential update coding for 3D video. In our telepresence system - the blue-c - we use a point-based 3D video technology which allows for differentially encoded 3D representations of human users. While we discuss the considerations which lead to the design of our three-stage 3D video pipeline, we also elucidate some critical implementation details regarding decoupling of acquisition, processing and rendering frame rates, and audio/video synchronization. Finally, we demonstrate the communication and networking features of the blue-c system in its full deployment. We show how the system can possibly be controlled to face processing or networking bottlenecks by adapting the multiple system components like audio, application data, and 3D video.     

基于PCI的视频编码卡的设计与实现

本文设计了一种面向工业控制场合的基于MPEG4的视频压缩编码卡.支持4路模拟视频图像的采集与A/D转换后,编码卡与主机之间依据PCI2.2标准,以PCI接口与主机实现通信.文中详细介绍了该编码卡的总体设计方案,系统采用最新的MPEG4压缩方式进行编码,为整个数字监控系统和视频网络传输系统提供了最优化的硬件设计.     

Bandwidth improvement of rat‐race couplers having left‐handed transmission‐line sections

A novel broadband rat‐race coupler has been investigated. The coupler utilizes an artificial left‐handed transmission line section for broadband phase response realization. Moreover, a narrowband model of left‐handed section has been shown to prove the couplers equivalent circuit at the center frequency. To broaden the operational bandwidth multisection quarter‐wave transformers have been proposed. The exemplary rat‐race coupler with two‐section impedance transformers has been designed and manufactured. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:341–347, 2014.     

Design of filtering directional coupler with improved performance

This letter presents a filtering directional coupler (FDC) with enhanced coupling and high directivity simultaneously. The proposed FDC is composed of a pair of coupled lines instead transmission line of a directional coupler. This coupled lines resonator increases the design parameters by which even/odd mode phase velocity can be compensated to improve the directivity and coupling level. The coupling enhancement can be explained by analyzing the even mode and odd mode circuit of the proposed coupler. A prototype of the proposed coupler is designed which provides a high directivity of 44 dB for 6 dB coupling level at 1 GHz frequency. The proposed coupler is designed, fabricated, and tested.     

Optical WDMA network design and function placement

The parallel use of multiple channels in a WDM star network means that too many packets may simultaneously arrive for the same destination station, necessitating the implementation of a destination-conflict-resolution function somewhere within the network. This paper considers explicitly, the placement of the destination-conflict-resolution function which specifies the location(s) where it should be performed, and when it should be performed. Traditional placements in which the function is located at all user stations and performed either before packet transmission (using the request-schedule-then-transmit principle) or after a destination conflict has been detected (using the detect-and-retransmit-if-lost principle), is compared with a central placement in which only one central station located at the entrance to the star coupler is responsible for detecting conflicts and optically buffering `otherwise lost' packets whilst they are en route to their destinations, until their destinations are free to receive them. The networks are evaluated considering their delay and throughout characteristics, the computational complexity of their protocols, their fault tolerance, and their hardware demands. The results presented suggest that significant performance improvements are achievable with the central placement since destination conflicts are resolved without having to retransmit packets nor waiting until the end of a request-broadcast-and-schedule phase before a given packet can be transmitted. The central station works with Space Division Multiplexed signals, just before they enter the star coupler. Its implementation is therefore simpler than when all stations are charged with this task, each of which has to attend to multiple WDM channels. Only `otherwise lost' packets are buffered so the network has low buffer memory requirements.     

基于插件的安全通讯模型研究

本文分析了Internet上个人用户与网站之间数据传输安全性的不足,并针对当前网络安全传输协议还不成熟的情况,提出在客户端浏览器上增加加／解密插件和在服务器端增加解密的CGI的方法来提高网络数据的保密性。     

基于SIM300C的远程数据采集传输终端设计

提出一种由GPRS模块SIM300C和单片机AT89S52组成的远程数据采集和传输终端,介绍了系统的硬软件设计.该系统以单片机为主控制器,配合A/D转换电路、SIM300C模块及其外围电路,将传感器端采集的模拟电压或电流信号进行A/D转换,由单片机将相应的数字量打包,通过串口发送给SIM300C模块,SIM300C模块自动将要发送的数据打包成TCP/IP数据包,经GPRS无线通信网络发送给远端的服务器.实验结果表明,该系统运行稳定可靠、数据传输及时高效.     

An Effective Error Resilient Packetization Scheme for Progressive Mesh Transmission over Unreliable Networks

When a 3D model is transmitted over a lossy network,some model information may inevitably be missing. Under such situation,one may not be able to visualize the receiving model unless the lost model information has been retransmitted. Progressive model transmission offers an alternative to avoid the "all or nothing situation" by allowing a model to be visualized with a degraded quality when only part of the model data has been received. Unfortunately,in case some model refinement information is missing,one may still need to wait for such information to be retransmitted before the model can be rendered with a desired visual quality. To address this problem,we have developed a novel error resilient packetization scheme. We first construct a Non-Redundant Directed Acyclic Graph to encode the dependencies among the vertex splits of a progressive mesh. A special Global Graph Equipartition Packing Algorithm is then applied to partitioning this graph into several equal size sub-graphs,which is packed as packets. The packing algorithm comprises two main phases:initial partition phase and global refinement phase. Experimental results demonstrate that the proposed scheme can minimize the dependencies between packets. Hence,it reduces the delay in rendering 3D models with proper quality at the clients.     

燃料电池车分布式控制网络的研究

介绍了燃料电池电动车分布式整车控制系统的任务和组成，分析了各ECU节点的功能。讨论了车载光纤CAN分布式通信网络的设计，提出了基于有源星形耦合器的光纤CAN星形通信网络，并设计了一个基于CPLD的带CANH、CANL接口的星形耦合器。简要介绍了燃料电池车分布式控制网络的传送协议。装车试验表明燃料电池车分布式控制网络设计合理，取得了满意的控制效果。