同步直流降压控制器可简化二次侧设计

茂达电子推出具高驱动能力的同步直流降压控制器APW7073。APW7073驱动两颗N信道的MOSFET，内部0．6V参考电压源的精度为1％，为高性能的应用提供了优化，非常适合开关式电源（SMPS），可用于二次侧同步降压方案。此设计可以让二次侧设计模块化，方便客户机种转换，维修及缩短生产流程检验时间。     

我们玩的就是TOP

虽然训练机种的传统首选是台式机，但在闲暇时间关注新型笔记本电脑的爱好，让我发现其实还可以从拥有强悍硬件配置的笔记本里发掘训练机种。在华硕A8Jp之前，我从没见过强此轻薄的游戏本本，何况还是在兼容了英特尔酷睿^TM2双核处理器和ATI Mobility Radeon X1700的前提下。     

6套6000元-130000元组合搭配推荐

这是一套入门级的搭配,所有器材都是在中国国内生产的外国品牌产品,立足于低价高质,并能满足于目前家庭影院最基本的需要。 DVD播放机选Pioneer目前的入门级机种DV-3500,虽然水平解象度只有500线以上,但该机在目前入门级机种中仍然是一款“高级机”,最诱人的地方在于,它的视频D/A转换芯片采用了54MHz/10bit的芯片,已经抛弃了过去延用多年的27MHz/10bit D/A转换芯片,因而输出的     

雅马哈RX—V2600影音接收放大器

去年10月，雅马哈向欧美市场推出了新一代影音接受放大器RX—V2600。这是这个档次产品中最先配备有二入一出HDMI接口和视频上转换的影音放大器．而且在视频电路的配备上．甚至还超过了上级机种RX-V4600．所以刚一上市．就引起AV发烧友的强烈关注。不过．这台新机在国内的上市时间要比欧美晚些．当本刊收到测试样机之时．它们还未在国内正式发布，所以．我们的测试在国内还是比较超前的。     

等离子、液晶同时进攻日立薄型电视卷土重来

日立日前一举发表11款薄型电视新产品，包括6款PDP机种与5款液晶机种，将于8月起陆续推出上市，其中5个机种同时配备硬件驱动与天线。     

安桥TX-SR804 7.1声道功放

从安桥新近推出的这部TX-SR804来看，我以为就全面性来做考量的话，它已经达到了很高的层次。而且，这部机种用到了安桥在更高级机种中所使用的部分技术。[编者按]     

dCS Debussy DAC

Debussy AC虽然是dcs的入门机种，但身上却集结7dCS的技术精华，包括采用与顶级机种Scarlatti相同的dCS ingDAC技术，而且还是最新的版本，同样运用dCS专利的5位超取样技术来达成最佳的音乐动态与线性表现。     

对农村有线广播用录音机标准的认识

在农村广播局(站)设备中,磁带录音机是一种使用频繁且维护难度较高的机种,这是因为录音机与其它声频设备相比,不仅有精密的电磁转换系统,而且还有复杂的机械走带系统。所以,在测量磁带录音机的基     

先锋VSX-D912-S AV功放

与早先相比，现在一些日本音响品牌的市场推广的策略有了显著的变化。举例来说，以前他们往往会在拿出一部样板机之后的一段时间里，才陆续推出向下兼容的中、平价级机种；而目前，这些品牌则会采取高端、平价机种     

奥林巴斯μ750 评测防抖进化

时尚轻薄的卡片式数码相机是如今市场上的热门机种，奥林巴斯的时尚机种一直以μ系列为主，在这个市场上打拼多年，μ系列在外形及功能上都得到了很大的进化，最新的进化便是加入了光学防抖功能。[编者按]     

呼吸机转换开关的设计与应用

从使用呼吸机病人角度出发,呼吸机在市电停电的情况下,呼吸机在一瞬间应该立即恢复供电,不然,对病人就有生命危险。呼吸机电源转换开关就是为解决这一问题而设计,此转换开关通过比较、延时自锁、延时驱动,控制呼吸机进行电源切换,提供给呼吸机正常的直流电源,保证呼吸机不间断地供电。     

甘肃省一级干线光缆传输设备-24V电源改造工程割接方案及实施

介绍了北京—呼和浩特—银川—兰州(简称京呼银兰), 西安—兰州—乌鲁木齐(简称西兰乌)甘肃省一级干线光缆传输设备-24V改-48V电源。电源不中断负载工程割接方案的比较。施工前的准备工作,具体割接步骤和注意事项。     

一种新型的自动无损倒换装置

本文介绍了一种用于数字微波通信的自动无损倒换，重点讲述了伪误码检测，逐位码比较，可变长度移位寄存器等方法对信码时延差进行自适应调整，以达到无损倒换的目的，较详细地给出了电路框图。     

A high performance four port PIN diode switch for televisionbroadcasting applications

A double-pole change-over shunt PIN diode switch for television bands IV and V is described. The switch is characterized by low insertion loss, good isolation, and excellent VSWR over an operating bandwidth of 650-860 MHz. It is suitable as a drop-in device in existing repeaters, requiring no returning of the RF circuitry. Although not designed to switch high-power signals, the switch should easily handle 50-100 W CW signals. The design is based on a short-step distributed bandpass filter, resulting in a very compact transmission-line structure     

微光机械振动传感器的设计与制作

采用旋涂和干法刻蚀技术,制作了一种新型有机集成微光机械振动传感器,其主要结构是由在硅基上制作的聚甲基丙烯酸甲酯(PMMA)悬臂梁和光波导集成光路组成,探测光路采用强度调制型开环差分探测,利用光-机转换功能,实现对微小振动量的检测。通过对该器件结构参数的优化设计和幅频特性分析表明,所制备的器件具有灵敏度高、线性度好、抗电磁干扰、工艺简单、成本低等优点。     

Adaptive group multicast with time-driven priority

This paper shows how to provide an adaptive real-time group multicast (many-to-many) communication service. Adaptive means that the number of nodes that transmit to the multicast group is continuously changing. In order to meet deterministic quality-of-service (QoS) requirements of a real-time group multicast, some communication resources are reserved. We show (1) how bandwidth is reserved for each multicast group and (2) how an active source can dynamically share the bandwidth allocated to this multicast group with other active group members. Quality-of-service support for a real-time multicast group is based on time-driven priority. In this scheme the time is divided into time frames of fixed duration, and all the time frames are aligned by using a common global time reference, which can be obtained from the Global Positioning System. Bandwidth is allocated to a multicast group as a whole, rather than individually to each user. The allocation is done by reserving time intervals within time frames in a periodic fashion. This type of allocation raises two problems that are studied in this paper: (1) scheduling: how time intervals are reserved to each multicast group and (2) adaptive sharing: how the active (transmitting) participants can dynamically share the time intervals that have been reserved for their multicast group. The proposed approach is based on the embedding of multiple virtual rings, one for each multicast group. By using the virtual rings, it is simple to route messages to all the participants while minimizing the bound on the buffer sizes and queueing delays. The final part of this paper introduces a scalable growth of the multicast group by adding multiple subtrees to the virtual ring     

Dipole group delay time

For wideband communication systems, the differential group delay time may be a critical parameter. Dipole type elements are frequently used in arrays at the low end of the microwave band; the group delay of a dipole is calculated for frequencies in the vicinity of a half wavelength. The calculation is based on the zero order impedance and a formula developed previously for computer use.     

紫外预电离Blumlein型准分子激光器放电特性-能量耦合关系

介绍了用上升时间为0.8毫微秒,耐压为60千伏的一组分压器和磁光法,研究紫外预电离Blumlein直型准分子器件能量耦合过程的结果;最后对最佳耦合形式等问题进行了讨论。     

Experimental verification of modal dispersion free characteristics in a two-mode optical fiber

Group delay time difference between LP01and LP11modes has been measured in a step-index type optical fiber over a two-mode region. The measured results have revealed that there exists a wavelength at which the group delay times of the two modes are coincident.     

基于K-means算法的时序GB-InSAR图像PS实时选择方法

GB-InSAR(Ground-based Interferometric Synthetic Aperture Radar,地基干涉合成孔径雷达)是一种新型的形变测量工具,应用于长期连续监测时,为了保证形变测量的准确性和实时性,通常需要将SAR图像进行分组处理,并基于PS(Permanent Scatterer,永久...