电子信息工程专业英语翻译
电子信息工程专业英语 课文翻译 Unit 12 译文
Unit 12 生物识别技术Unit 12-1第一部分:指纹识别在所有的生物技术中,指纹识别是最早期的一种技术。
我们知道,每个人都有自己独特的、不可变更的指纹。
指纹是由手指表皮上的一系列峰谷组成的。
指纹的独特性是由这些峰谷的形状以及指纹的细节点所决定的。
指纹的细节点是指纹局部凸起处的一些特性,这些特性出现在凸起的分叉处或是凸起的截止处。
指纹匹配技术可以被分为两类:基于细节的指纹匹配技术和基于相关性的指纹匹配技术。
基于细节的指纹匹配首先要找出细节点,然后在手指上对应出与它们相关的位置,如图12.1所示。
但是,使用这种方法存在一些困难。
要精确地提取指纹的细节点是很困难的。
而且,这种方法不能很好地考虑指纹峰谷的整体形状。
基于相关性的指纹匹配技术可以解决部分基于细节的指纹匹配方法存在的问题,但它也存在一些自身的缺陷。
基于相关性的匹配技术需要给出已注册过的特征点的精确位置,并且该方法会受图像平移和旋转的影响。
图12.1 基于细节的指纹匹配基于细节的指纹匹配技术在匹配不同大小的细节模型时(未注册过的)会存在一些问题。
指纹上局部的凸起结构不能完全由指纹细节实现特征化。
我们可以尝试另一种表达指纹的方法,它可以获得更多的指纹局部信息并且得到固定长度的指纹编码。
于是,我们只需要计算两个指纹编码之间的欧几里得距离,匹配过程有望变得相对简单。
研发对于指纹图像中噪声更稳健并能实时提供更高精度的算法是重要的。
商用指纹(身份)认证系统对给定的错误接受率要求具有很低的错误拒绝率。
在这点上,任何一项简单的技术都很难实现。
我们可以从不同的匹配技术中汇总多个证据从而提高系统的总体精确度。
在实际应用中,传感器、采集系统、性能随时间的变化是关键因素。
为了评价系统性能,我们有必要对少数使用者在一段时间内进行现场试验。
每天我们可以从法医鉴定、出入口控制、驾驶证登记等多个方面的应用中采集并保存大量的指纹。
基于指纹的自动识别系统需要把输入的指纹与数据库中大量的指纹进行匹配验证。
电子信息工程专业英语翻译清华出版社nglish for IT and EE-08
(bps) of transmitted information in the sense that going to a
higher information rate requires a higher frequency. Thus, the first observation from the frequency line would be that, for optical carriers, which have frequencies in the hundreds of THz, information bandwidth is in some sense free. 信息的带宽在 某种意义上是 免费的 因此在较高的信息率要求较高 的频率这层意义上,要考虑传 输信息的每个bps成本问题
与用于信息传输的光学技术 的潜力有关的
仔细研究表8.1中的频率表可以看到各种用于信息传 A frequency line which gives the wavelengths , the frequencies
, and the photon energy p for the various regions of the frequency
9
2
As wavelengths decrease to approach the size of circuit
components, circuit elements are no longer lumped, and leads
can act as reflective components and/or antennas and lumped
电子信息工程专业英语英译汉翻译
1 The transistor is what started the evolution of the modern computer industry in motion.晶体管开启了现代电脑工业的革命2 The storage cell only requires one capacitor and one transistor, whereas a flip-flop connected in an array requires 6 transistors.存储单元仅需要一个电容和晶体管,并而不像触发器整列那样需要6个晶体管3 There has been a never ending series of new op amps released each year since then, and their performance and reliability has improved to the point where present day op amps can be used for analog applications by anybody.从此以后每年都有新系列的运放发布,他们的性能和可靠性得到了提升,如今任何人都能用运放来设计模拟电路。
4 This is capable of very high speed conversion and thus can accommodate high sampling rates, but in its basic form is very power hungry.它具有高速转换能力,从而能适应高速采样速率,但它的基本形式非常耗电。
5 During the “on” period , energy is being stored within the core material of the inductor in the form of flux.在”on”阶段,能量以涌浪形式存储在电感的核芯材料里面6 The design goal of frequency synthesizers is to replace multiple oscillators in a system, and hence reduce board space and cost.频率合成器的设计目标是取代系统中多个振荡器,从而减小板卡面积和成本。
电子信息工程专业英语翻译清华出版社English for IT and EE-09
定理规定:采样频率必须 定理规定: 大于两倍的信号带宽
信息科学与电子工程专业英语
Part I
Digital Signal Processing
New Words
sub-field 分领域,子领域 sub分领域, sensor array 传感器阵列 algorithm 算法 purposepurpose-designed 针对目的设计的 integrated circuits 集成电路 wavelet 小波 informed 有知识的,有见闻的 有知识的, crosscross-correlation 互相关 discretization 离散化 partition 分割,分区 分割, sonar 声呐 biomedical 生物特征的 abbreviate 缩写,缩略 缩写, applicationapplication-specific 面向应用的 autocorrelation 自相关 baseband 基带 spatial domain 空间域 interval 间隔 quantization 量化 finite set 有限的集
当灵活性和快速开发比大批量生产的 成本更重要时,DSP算法也可以用现 成本更重要时,DSP算法也可以用现 场可编程门阵列来实现。 场可编程门阵列来实现。
9
4 DSP domains
In DSP, engineers usually study digital signals in one of the following domains: time domain (one-dimensional signals), (onespatial domain (multidimensional signals), frequency domain, autocorrelation domain, and wavelet domains. They choose the domain in which to process a signal by making an informed guess (or by trying different possibilities) as to which domain best represents the essential characteristics of the signal.3 他们按某些依据来猜测(或试验不同的可能 他们按某些依据来猜测( 性)那一个域能够最好地表示信号的本质特 性来选择在其中进行信号处理的域。 性来选择在其中进行信号处理的域。
最新电子信息工程专业英语课文翻译(第3版)
电子信息工程专业英语教程第三版译者:唐亦林p32In 1945 H. W. Bode presented a system for analyzing the stability of feedback systems by using graphical methods. Until this time, feedback analysis was done by multiplication and division, so calculation of transfer functions was a time consuming and laborious task. Remember, engineers did not have calculators or computers until the '70s. Bode presented a log technique that transformed the intensely mathematical process of calculating a feedback system's stability into graphical analysis that was simple and perceptive. Feedback system design was still complicated, but it no longer was an art dominated by a few electrical engineers kept in a small dark room. Any electrical engineer could use Bode's methods find the stability of a feedback circuit, so the application of feedback to machines began to grow. There really wasn't much call for electronic feedback design until computers and transducers become of age.1945年HW伯德提出了一套系统方法,用图形化方法来分析反馈系统的稳定性。
专业英语(电子与信息工程类)翻译
1.As data networks advanced…also grew more complex.由于数据网络从面向终端的系统向分组交换、计算机与计算机连接的方向发展, 执行网络功能所必需的协议也变得愈来愈复杂。
2.An additional bit called a parity bit…during transmission.在每个字符的后面有时还包括一个称为奇偶校验位的附加位, 它们测试数据位在传输过程中是否被意外改变。
3.As already stated, with…downlink(FDD paired bands).如前所述, 在非对称通信量应用中, TD-SCDMA利用可用频谱的效率比其他3G标准高, 因为它在只利用一个频带(TDD单一频带)而不是两个独立的频带(FDD成对频带)进行上行与下行通信。
4.Although often simpler to implement, …digital modulation.虽然光纤系统的模拟调制易于实现, 但其效率较低, 且要求在接收端有比数字调制高得多的信噪比。
5.At present, the bandwidth…electronics ()is possible.目前传输100km的几吉赫兹的调制信号和传输300km的几百兆赫兹的调制信号都是可能的, 因此光纤系统的可用带宽并没有得到充分利用。
6.Both TD-SCDMA deployments-TSD…unpaired bands awarded.TD-SCDMA的两种部署——TSM和TDDCLR的数据速率、频谱利用率、覆盖率、移动性和可靠性等性能是一样的, 并基本上为所有取得非成对TDD频段牌照的运营商所采用。
7.Crossbar sw itching was carried…selection for all calls.纵横制交换由一个称为标志器的特定电路控制, 标志器提供整个号码的公共控制并选择所有呼叫的路由。
电子信息工程专业英语课文翻译(第3版)
电子信息工程专业英语教程第三版译者:唐亦林p32In 1945 H. W。
Bode presented a system for analyzing the stability of feedback systems by using graphical methods. Until this time, feedback analysis was done by multiplication and division,so calculation of transfer functions was a time consuming and laborious task. Remember, engineers did not have calculators or computers until the ’70s。
Bode presented a log technique that transformed the intensely mathematical process of calculating a feedback system’s stability into graphical analysis that was simple and perceptive. Feedback system design was still complicated, but it no longer was an art dominated by a few electrical engineers kept in a small dark room。
Any electrical engineer could use Bode's methods find the stability of a feedback circuit,so the application of feedback to machines began to grow。
电子信息工程专业英语翻译
Cooperative Peer-to-Peer Streaming:An Evolutionary Game-TheoreticApproachYanChen,StudentMember,IEEE,BeibeiWang,StedengMember,IEEE,W.SabrinaLin,Member,IEEE,Yongle Wu,Student Member,IEEE,and K,.J.Ray Liu,Fellow,IEEE Abstrac t—While peer-to-peer(P2P)video streaming systems have achievedpromising results,they introduce a large number of unnecessary traverse links,which consequengly leads to substantial network inefficiency.To address this problem and achieve better streaming performance,we propose to enable cooperation among “group peers,”which are geographically neighboring peers with large intra-group upload and download bandwidths.C onsidering the peers’selfish nature,we formulate the cooperative streaming problem as an evolutionary game and derive,for every peer,the evolutionarily stable strategy(ESS),which is the stable Nash equilibrium and no one will deviate from.Moreover,we propose a simple and distributed learning algorithm for the peers to converge to the ESSs. ed from the peer’sown padtWith the propo sed algorithm,each peer decides whether to be an agent who downloads data from the peers outside the group or a free rider who downloads data from the agents by simply tossing a coin,where the probability of being a head for the coin is learned from the peer’s own past payoff history.Simulation results shou to the traditional non-cooperative P2P schemes,the proposed cooperative scheme achieves much better performance in terms of social welfare,probability of real-time streaming,and video quality(source rate). IndexTerms—Coopreative streaming,distributed learning,evolutionary,game theory,peer-to-peer(P2P),replicator dynamics.ⅠIntroductionWith the rapid development of signal processing,communication, and networking technologies,video-over-IP applications become more and more popular and have attracted millions of users over the Internet.One simple solution to video streaming over Internet is the client-server service model,where the video is streamed directly from a server to clients.However with the client-server service model, the upload bandwidth of the server grows proportionally with the number of clients, whice makes the large-scale video streaming impractical.To reduce the workload of the server,peer-to-peer(P2P)service model is proposed, where a peer not only acts as a client to download data from the network,but also acts as a server to upload data for the other peers in the network.The upload bandwidth of the peers reduces the workload placed on the server dramatically,which makes large-scale video streaming possible,Recently,several industrial large-scale P2P video streaming systems have been developed,includingCoolstreaming,PPLive,PPStream,UUSee,and Sopcast. Studies show that these systems can support hundreds of thousands of users simultaneously.While P2P video streaming systems have schieved promising results, they have several drawbacks. First, there are a large number of unecessary traverse links within a provider’s network.As observed in ,each P2P bit on the Verizon network,As observed in,each P2P bit on the Verizon network traverses 1000 miles and takes 5.5 metro-hops on average,Second,there is a huge number of cross Internet service provider traffic,The studies showed that 50%-90%of the existing local pieces in active peers are downloaded externally.Third,the differences in playback time among peeers can be as high as 140s,and the lag can be greater if the source rate is higher,Fourth,most of the current P2P systems assume that all peers are willing to contribute their resources.however,this assumption may mot be true since the P2P systems are self-organizing networks and the peers are selfish by nature.Note that the selfish peers will act as free-riders if being free-riders can improve their utilities.译文:对等网络流:进化论的赛局的方法杨晨,学生;王蓓蓓,学生;塞布丽娜林,IEEE成员;永乐吴,学生;永乐刘,学生摘要:而对等网络视频流系统取得了很有前途,但这样的技术引进大量不必要的导线连接,从而导致实质性的网络无效率。
电子信息工程专业英语翻译
2
This figure shows both the silicon structures of these elements
and their graphical symbolic representation as would be seen
in a circuit diagram. The BJT shown is an NPN transistor,
任何实质性的数字逻辑(电路)都将十分 庞大,因为要在各种逻辑门中每实现一种 都需要多个晶体管。
16
5
At the time of the invention of the transistor in 1947 by John
Bardeen, Walter Brattain, and William Shockley, the only way
N型硅半导体掺入磷元素,而 P型硅半导体掺入硼元素。
8
2
A transistor is constructed by creating a sandwich of differently doped semiconductor layers. The two most common types of transistors, the bipolar-junction transistor (BJT) and the field-effect transistor (FET) are schematically illustrated in Figure 2.1.
半导体材料上制作晶体管或二极管 所形成的小芯片用塑料封装以防损 伤和被外界污染。
14
4
Small wires are connected within this package between the semiconductor sandwich and pins that protrude from the package to make electrical contact with other parts of the intended circuit.
电子信息工程专业英语 English for Electronic Information Engineering
0.1 科技英语的特点 features
0.1.2 词汇 Vocabularies or words
0.1 科技英语的特点 features
0.1.2 词汇 Vocabularies or words
❖转意词汇 Transfered words
有些单词的通用含义很接近,但它们的专业含义却完全不 同,如: differential :微分 difference :差分 probability :概率 possibility :可能性
❖ 语法上特点:常用一般现在时时态;
复杂长句多; 被动语态多;(“被”、“经过”、“受了”、 “由于”) 非谓语动词多;(动名词、分词、不定式) 非人称语气,常用It作主语; 条件句多,常用If 语句。
0.1 科技英语的特点 features
科技英语与普通英语相比有自己的特点: ❖合词成汇词G的S:M特,点G:PRS , CDMA , GPS , CPU , USB , LCD multimet大er量万使用用表专业,词in汇te、rfa转c意e 词接汇口;、界面
专业文献(摘要)的写作练习
学习本课程的主要方式
课前预习
课堂讲解重点难点
课后练习
课堂练习、小测ຫໍສະໝຸດ 议 ❖ 准备笔记本 ❖ 准备英汉专业词典
要求 ❖ 独立完成作业 ❖ 遵守课堂纪律
Lesson 0 科技英语基础知识 The Basic Knowledge
of Scientific and Technical English
电子信息工程专业专业英语三千字翻译
Unit3 computer architecture and microprocessors3--1 Computer Architecture1) Computer architecture , in computer science , is a general term referring to the structure of all or part of computer system . The term also covers the design of system software , such as the operating system (the program that controls the computer) , as well as referring to the combination of hardware and basic software that links the machines on a computer network . Computer architecture refers to an entire structure and to the details needed to make it functional . Thus , computer architecture covers computer systems , microprocessors , circuits , and system programs . Typically the term does not refer to application programs , such as spreadsheets or word processing , which are required to perform a task but not to make the system run .2)1.Design Elements3) In designing a computer system , architects consider five major elements that make up the system's hardware : the arithmetic /logic unit , control unit , memory , input , and output . The arithmetic /logic unit performs arithmetic and compares numerical values . The control unit directs the operation of the computer by taking the user instructions andtransforming them into electrical signals that the computer 's circuitry can understand . The combination of the arithmetic /logic unit and the control unit is called the central processing unit (CPU) . The memory stores instructions and data . The input input and output sections allow the computer to receive and send data , respectively .4) Different hardware architectures are required because of the specialized needs of systems and users . One user may need a system to display graphics extremely fast , while another system may have to be optimized for searching a database or conserving battery power in a laptop computer .5) In addition to the hardware design , the architects must consider what software programs will operate the system . Software , such as programming languages and operating systems , makes the details of the hardware architecture invisible to the user . For example , computers that use the C programming language or a UNIT operating system may appear the same from the user's viewpoint , although they use different hardware architectures .6)2.Processing Architecture7) When a computer carries out an instruction , it proceeds through five steps . First ,the control unit retrieves theinstruction from memory , for example , an instruction to add two numbers . Second , the control unit decodes the instruction into electronic signals that control the computer . Third , the control unit fetches the data (the two numbers) . Fourth , the arithmetic/logic unit performs the specific operation ( the addition of the two numbers ) . Fifth , the control unit saves the result ( the sum of the two numbers ) .8) Early computers used only simple instructions because the cost of electronic capable of carrying out complex instructions was high . As this cost decreased in the 1960s , more complicated instructions became possible . Complex instructions ( single instructions that specify multiple operations ) can save time because they make it unnecessary for the computer to retrieve additional instructions . For example , if seven operations are combined in one instruction , then six of the steps that fetch instructions are eliminated and the computer spends less time processing that operation . Computers that combine several instructions into a single operation are called complex instruction set computers ( CISC ) .9) However , most programs do not often use complexinstructions , but consist mostly of simple instructions . When these simple instructions are run on CISC architectures , they slow down processing because each instruction--whether simple or complex --takes longer to decode in a CISC design . An alternative strategy is to return to designs that use only simple , single--operation instruction sets and make the most frequently used operations faster in order to increase overall performance . Computers that follow this design are called reduced instruction set computers ( RISC ) .10) RISC designs are especially fast at the numerical computations required in science , graphics , and engineering applications . CISC designs are commonly used for non-numerical computations because they provide special instruction sets for handling character data , such as text in a word processing program . Specialized CISC architectures , called digital signal processors , exist to accelerate processing of digitized audio and video signals .11)3.Open and Closed Architectures12) The CPU of a computer is connected to memory and to the outside world by means of either an open or a closed architecture . An open architecture can be expanded after the system has been built , usually by adding extra circuitry ,such as a new microprocessor computer chip connected to the main system . The specifications of the circuitry are made public , allowing other companies to manufacture these expansion products .13) Closed architectures are usually employed in specialized computers that will not require expansion , for example , computers that control microwave ovens . Some computer manufacturers have used closed architectures so that their customers can purchase expansion circuitry only from them . This allows the manufacture to charge more and reduces the options for the consumer .14)work Architecture15) Computers communicate with other computers via networks . The simplest network is a direct connection between two computers . However , computers can also be connected over large networks , allowing users to exchange data , communicate via electronic mail , and share resources such as printers .16) Computers can be connected in several ways . In a ring configuration , data are transmitted along the ring and each computer in the ring examines this data to determine if it is the intended recipient . If the data are not intended fora particular computer , the computer passes the data to the next computer in the ring . This process is repeated until the data arrive at their intended destination . A ring network allows multiple messages to be carried simultaneously , but since each message is checked by each computer , data transmission is slowed .17) In a bus configuration , computers are connected througha single set of wires , called a bus . One computer sends data to another by broadcasting the address of the receive and the data over the bus . All the computers in the network look at the address simultaneously , and the intended recipient accepts the data . A bus network , unlike a ring network , allows data to be sent directly from one computer to another . However , only one computer at a time can transmit data . The others must wait to send their messages .18) In a star configuration , computers are linked to a central computer called a hub . A computer sends the address of the receiver and the data to the hub , which then links the sending and receiving computers directly . A star network allows multiple messages to be sent simultaneously , but it is more costly because it uses an additional computer , the hub , to direct the data .19)5.Recent Advances20) One problem in computer architecture is caused by the difference between the speed of the CPU and the speed at which memory supplies instructions and data . Modern CPUs can process instructions in 3 nanoseconds ( 3 billionths of a second ) . A typical memory access , however , takes 100 nanoseconds and each instruction may require multiple accesses . To compensate for this disparity , new computer chips have been designed that contain small memories , called caches , located near the CPU . Because of their proximity to the CPU and their small size , caches can supply instructions and data faster than normal memory . Cache memory stores the most frequently used instructions and data and can greatly increase efficiency .21) Although a large cache memory can hold more data , it also becomes slower .To compensate , computer architects employ designs with multiple caches . The design places the smallest and fastest cache nearest the CPU and locates a second large and slower cache farther away . This arrangement allows the CPU to operate on the most frequently accessed instructions and data at top speed and to slow down only slightly when accessing the secondary cache . Using separatecaches for instructions and data also allows the CPU to retrieve an instruction and data simultaneously .22) Anther strategy to increase speed and efficiency is the use of multiple arithmetic/logic units for simultaneous operations , called super scalar execution . In this design , instructions are acquired in groups . The control unit examines each group to see if it contains instructions that can be performed together . Some designs execute as many as six operations simultaneously . It is rare , however , to have this many instructions run together ,so on average the CPU does not achieve a six-fold increase in performance . 23) Multiple computers are sometimes combined into single systems called parallel processors . When a machine has more than one thousand arithmetic/logic units , it is said to be massively parallel . Such machines are used primarily for numerically intensive scientific and engineering computation .Parallel machines containing as many as sixteen thousand computers have been constructed .3-3 VLIW Microprocessors24) When Transmeta Corp. revealed its new Crusoe of processors last month ,experts weren’t surprised to learn that the chips are based on Very Long Instruction Word(VLIW)technology .VLIW has become the prevailing philosophy of microprocessor design , eclipsing older approaches such as RISC and complex instruction set computing(CISC) .25) All microprocessor designs seek better performance within the limitations of their contemporary technology. In the 70s of 20th century ,for example ,memory was measured in kilobytes and very expensive .CISC was the dominant approach because it conserved memory .26) In the CISC architecture . there can be hundreds of program instructions-simple commands that tell the system to add numbers, store values and display results. If all instructions were the same length , the simple ones would waste memory .Simple instructions require as little as 8 bits of storage space , while the most complex consume 120 bits .27) Variable-length instructions are more difficult for a chip to process, though, and the longer CISC instructions are especially complex. nonetheless ,to maintain software compatibility, modern chips such as Intel’s Pentium III and Advanced Micro Devices Inc.’s Athlon must still work with all troublesome CISC instructions that were designed in the 1980s , even though their original advantage-memory conservation-isn’t as important .28) In the 1980s , RAM chips got bigger and bigger in capacity while their prices dropped . The emphasis in CPU design shifted to relatively simple , fixed-length instructions , always 32 bits long .Although this wastes some memory by making programs bigger ,the instructions are easier and faster to execute .29) The simplicity of RISC also makes it easier to design superscalar processors-chips that can execute more than one instruction at a time .This is called instruction-level parallelism. Almost all modern RISC and CISC processors are superscalar. But achieving this capability introduced significant new levels of design complexity.30) VLIW chips can cost less , burn less power and achieve significantly higher performance than comparable RISC and CISC chips But there are always trade-offs. One is code expansion-programs grow larger , requiring more memory. Far more important , though , is that compilers must get smarter .A poor VLIW complier will have a much greater negative impact on performance than would a poor RISC or CISC compiler .31) VLIW isn’t a magic bullet , but it’s the new wave in microprocessor design .Within a few years , it’s certain that at least some of your software will be running on VLIW chips .单元3 电脑体系和微处理器3-1 电脑体系电脑体系,在电脑科技中,是一个依据整个或部分电脑结构的通用术语,这个术语也包含软件系统的设计,例如这个操作系统(控制电脑的程序),以及依据这个在电脑网络中连接主机的硬件和基本的软件的结合体。
电子信息工程专业英语 课文翻译 Unit 05 译文
Unit 5 多址技术Unit 5-1第一部分:多址技术:频分多址、时分多址、码分多址多址方案用于使许多用户同时使用同一个固定带宽的无线电频谱。
在任何无线电系统中分配的带宽总是有限的。
移动电话系统的典型总带宽是50MHz ,它被分成两半用以提供系统的前向和反向连接。
任何无线网络为了提高用户容量都需要共享频谱。
频分多址(FDMA )、时分多址(TDMA )、码分多址(CDMA )是无线系统中由众多用户共享可用带宽的三种主要方法。
这些方法又有许多扩展和混合技术,例如正交频分复用(OFDM ),以及混合时分和频分多址系统。
不过要了解任何扩展技术首先要求对三种主要方法的理解。
频分多址在FDMA 中,可用带宽被分为许多个较窄的频带。
每一用户被分配一个独特的频带用于发送和接收。
在一次通话中其他用户不能使用同一频带。
每个用户分配到一个由基站到移动电话的前向信道以及一个返回基站的反向信道,每个信道都是一个单向连接。
在每个信道中传输信号是连续的,以便进行模拟通信。
FDMA 信道的带宽一般较小(30kHz ),每个信道只支持一个用户。
FDMA 作为大多数多信道系统的一部分用于初步分割分配到的宽频带。
将可用带宽分配给几个信道的情况见图5.1和图5.2。
时分多址TDMA 将可用频谱分成多个时隙,通过分配给每一个用户一个时隙以便在其中发送或接收。
图5.3显示如何以一种循环复用的方式把时隙分配给用户,每个用户每帧分得一个时隙。
TDMA 以缓冲和爆发方式发送数据。
因此每个信道的发射是不连续的。
待发送的输入数据在前一帧期间被缓存,在分配给该信道的时隙中以较高速率爆发式发送出去。
TDMA 不能直接传送模拟信号因为它需要使用缓冲,因而只能用于传输数字形式的数据。
由于通常发送速率很高,TDMA 会受到多径效应的影响。
这导致多径信号引起码间干扰。
TDMA 一般与FDMA 结合使用,将可用的全部带宽划分为若干信道。
这是为了减少每个信道上的用户数以便使用较低的数据速率。
电子信息工程专业英语 课文翻译 Unit 04 译文
Unit 4 通信和信息论Unit 4-1第一部分:远程通信远程通信是远距离通信的信号传输,在现代,通常这个过程需要电子发射机发射电磁波,但是在早期远程通信包括使用烟火信号,鼓或旗语或日光仪。
今天,远程通信很普遍的,助推这一过程的设备如电视,无线电和电话在世界的许多地区都已很普遍。
还有连接这些设备的许多网络,包括计算机网络,公共电话网,无线电网和电视网络。
互联网上的计算机通信是众多通信的一个例子。
通信系统通常由通信工程师设计。
在这个领域中早期的发明家有Alexander Graham Bell, Guglielmo Marconi 和John Logie Baird。
通信在当今的世界经济发展中起着举足轻重的作用,通信产业的税收在世界总产值的比例已接近百分之三。
基本要素每个通信系统包括三个基本要素:采集信息并能将其转换为信号的发射机,传输信号的传输媒介,接收信号并能将其还原为有用信息的接收机。
考虑一个无线电广播的例子。
广播塔是发射机,收音机是接收机,传输媒介是自由空间。
通常通信系统都是双向的,一个设备既做发射机又做接收机,即收发器。
例如,移动手机就是一个收发器。
电话线上的通信称为点对点通信,因为只在一个发射机和一个接收机之间。
通过无线电广播的通信称为广播(一对多)通信,因为通信是在一个大功率的发射机和许多接收机之间。
模拟或数字信号可以是模拟的,也可以是数字的。
在模拟信号中,信号根据信息而连续变化。
在数字信号信息被编码为一组离散值(如,1和0)。
在传输过程中,模拟信号中的信息会因噪声而退化。
相反,只要噪声不超过一定的阈值,数字信号中的信息是不会丢失的。
这是数字信号相对于模拟信号一个关键的优点。
网络网络是由一个相互通信的发射机、接收机或收发机的集合。
数字网络由一个或多个路由器组成,路由器正确地将数据发送给用户。
模拟网路由一个或多个交换器组成,交换器在两个或多个用户间建立连接。
这两种网络都需要中继器,用于远距离传输时的放大或重建信号。
电子信息工程专业英语 课文翻译 Unit 08 译文
Unit 8 光通信Unit 8-1第一部分:电磁频谱仔细研究表8.1中的频率表可以看到各种用于信息传输的光学技术的潜力。
人们所感兴趣的“现代”常规通信系统的信息传播速率通常相应于电话系统中的音频、商用广播系统中的无线电频率、或是最先进的视频节目分配系统中的数字电视数据率。
这些数据率通常低于几个吉赫兹(GHz)。
如果传输这样的信息不是将它加载到光纤上,而是加载在略高于最大速率的射频载波上,则此射频载波就会是厘米波或是波长更长一些的波。
用光载波则有很大的优越性。
一个明显的优点就是光纤的低损耗和方向性。
载波的数据率显然必须高于信息速率。
通信系统的一个基本原则是频率愈高,技术就愈复杂。
处理微波就比处理无线电波更困难。
随着波长减小到接近于电路元件的尺寸,电路单元就不再是集总的,导线可起到反射元件以及(或)天线的作用,集总单元则成为电磁谐振器。
这通常意味着当发送的信息较多时,代价也较高,因此在较高的信息率要求较高的频率这层意义上,要考虑传输信息的每个bps的成本问题。
于是,观察上述频率表得到的第一个结论就是,对于频率为数百特赫兹(THz)的光载波而言,信息的带宽在某种意义上是免费的。
就是说与大多数器件相比,光的波长是如此之小,以至于所用技术与电和微波有根本的不同。
一旦我们具备了这样的技术,则无论信息率有多高,再也没有必要改变载波了,因为载波频率高于任何现实信息率所能达到的程度。
不过带宽也不是完全免费的,因为编码器和解码器必须工作在相应于信息率的频率上,而系统其余部分大都只需要处理载波和调制。
如果一个元件可以工作在5⨯1014Hz的频率上,在这个频率信息偏移千分之一(相应于500吉赫兹的信息率)对器件的性能将没有什么影响。
因此,只要系统已经建立起来,大体上就可以随意升级系统而不会涉及常规系统中改变电磁载波所需付出的那种代价。
光波的宽频带一个结果就是光载波可以同时携带许多不同电话信号和电视节目等。
通常实现这种同时传输多路信息的过程(至少以同步格式实现)称为时分复用。
电子信息工程专业英语翻译清华出版社English for IT and EE-12
noise in fingerprint images and deliver increased accuracy in
real-time.1
研发对于指纹图像中噪声更稳健 并能实时提供更高精度的算法是 重要的。
extraction algorithm relies heavily on the quality of the input fingerprint images.
18
7
In order to ensure that the performance of an automatic
fingerprint identification/verification system will be robust
with respect to the quality of the fingerprint images, it is
essential to incorporate a fingerprint enhancement algorithm in the minutiae extraction module.5
It is difficult to extract the minutiae points accurately when
the fingerprint is of low quality. Also this method does not
take into account the global pattern of ridges and furrows.
matching of the fingerprints. An input fingerprint is first
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电子信息工程专业英语-教师用书Part 1第一课关于电子技术一、课文习题参考答案Ⅰ. (1)alternating current circuits (2)semiconductor diodes(3)passive component(4)the combinatory logic electric circuit(5)rectification(6)Laplace transform(7)inductor(8)Fourier series and Fourier transformⅡ.(1)操纵理论(2)场效应管三极管(3)布尔代数(4)稳压(5)相关性和功率谱密度(6)滤波器类型(7)模/数转换器(8)时序逻辑电路的分析与综合Ⅲ.(1)Electronics is a part of the larger field of electricity. The basic principles of electricity are also common to electronics. Modern advances in the field of computer, control system, communications have a close relationship with electronics. The field of electronics includes the electron tube, transistor, integrated circuit and so on.(2) Direct current circuits & Alternating current circuits,Analog electronics,Digital electronics,signal and systems,Circuit theory and design, Control theory, Microcontroller systems,Computer programming for engineering applications.(3) This curriculum mainly introduces the characteristics of semiconductor devices in linear application content involved in semiconductor diodes (PN junction diodes, special purpose diodes), transistors (field effects and bipolar transistors), signal amplifiers, practical amplifiers, biasing circuits, operational amplifiers circuit and other circuits (rectification, regulation and DC power supplies).(4) This partial studies take the basic electric circuit theory and the operational amplifier knowledge as the foundation. The main study goal is to enhance understanding of the electric circuit theory. Its main content includes the elementary theory in circuit theory (network functions, characteristic frequencies), types of filter (lowpass,bandpass), review of operational amplifiers (design of first and second order using operational amplifiers, cascade design), filter characteristics(Butterworth, Chebyshev, frequency transformations in design, sensitivity design ofpassive LC ladder filters and a brief introduction to switched capacitor filters).(5) Perfect.二、参考译文电子学的进展电子学是电学的一部份。
有关电学的大体原理也都经常使用于电子学中。
近代运算机、操纵系统和通信等方面的进展都与电子学有着紧密的关系。
电子学的范围包括电子管、晶体管和集成电路等。
电子学始于1883年,即爱迪生研究材料时发觉真空管能够用作电灯的那一年。
第一个电子装置显示出其非线性的单一电子特点,可是不能产生放大信号。
1905年佛莱明在英国制成了第一个二极管。
1906年德·福雷斯特在美国研制了第一个三极管,那个时候真空管是无线电设备中一个奇异的器件。
真空管普遍应用于通信工业,真空管第一用于收音机,然后用于电视。
发明了半导体器件后,真空二极管的利用呈迅速下降趋势,因为半导体器件具有真空管的许多功能。
第一个大型数字电子系统是特殊用途的真空管电路,称为电子数字积分运算机。
ENIAC 是运算机工业的前驱。
1948年晶体管问世,为电子学的进展作出了重大奉献。
今天所说的电子技术事实上是在发觉晶体管效应以后开始进展的。
晶体管为电子技术开辟了道路,初期的晶体管用锗做成,要紧用于小型袖珍调幅收音机。
硅晶体管于20世纪50年代末代替了锗晶体管,它再次给电子学带来了革命性进步,更重要的是它为运算机世界开辟了道路。
各类类型的运算机开始在市场上显现,研究工作进入一个迅速进展的时期。
在电子技术进展进程中还存在其他的问题,如电子器件在一块主板上的安装问题。
对此,德克萨斯仪器公司的Jack Kilby找到了专门好的答案。
他提议不用任何导线,把电阻、电容和晶体管在同一片晶片内部连接起来,令人难以想象的是他的方式成功了,从此诞生了集成电路工业。
集成电路工业的商业成绩是在以数字逻辑家族为代表的标准产品的基础上取得成功的。
集成电路从小型电路不断进展成大规模集成电路。
20世纪70年代末,通过十年的进展,大规模集成电路的时期终止了,迎来的是集成电路的新时期。
那个时期以一个单一电路包括愈来愈多的元件为特点,这一电路被称为超大规模集成电路。
电子技术正在飞速进展,电子工业也正以又一庞大的步伐向前迈进。
电子专业的课程内容1.直流电路和交流电路这门课程包括无源器件(电阻、电容和电感)的大体理论和用直流电源供电的电路网络,无源电路中的交流电流和交流电压的作用和直流电机、三相电机和变压器等知识。
2.模拟电子技术那个课程要紧介绍半导体器件在线性应用范围中的特点,内容包括二极管(半导体二极管、PN结二极管、特殊二极管)、三极管(场效应管三极管、晶体三极管)、信号放大电路、实际放大电路、偏置电路、运算放大器电路、其他电路(整流、稳压、直流电压源电路)。
3.数字电子技术那个课程学习以下内容:逻辑电路的大体概念、数字表示方式、组合逻辑电路、CMOS 数字电路、逻辑运算定律和布尔代数、数字运算(二进制、十六制、整数)、组合逻辑电路的分析与综合、时序逻辑电路的分析与综合、寄放器、计数器、总线系统和逻辑电路设计中的运算机辅助设计工具(软件)。
4.信号与系统那个单元讲解许多工程信号和系统的大体性质和在信号和系统处置中必需的数学工具,要专门强调的是线性时不变系统的时域和频域模型。
这些概念对学习通信、操纵、电力系统和信号处置等领域的许多单元都会用到。
学习信号与系统需要微分、积分、微分方程和线性代数等基础知识。
课程包括持续时刻信号(分类及性质)、系统的大体性质(线性、时不变性、因果性和稳固性)、线性时不变系统(由微分方程描述的特点和卷积)、傅立叶级数和傅立叶变换(概念、性质、频率响应和基于傅立叶变换的线性时不变系统的分析、采样、相关性和功率谱密度)、拉普拉斯变换(概念、性质、基于拉普拉斯的线性时不变系统的分析、用拉普拉斯变换求解状态方程)。
5.电路理论和设计那个部份的学习是以大体电路理论和运算放大器知识为基础的。
要紧的学习目标是增强对电路理论的明白得,其要紧内容有电路理论的大体理论(网络函数、特点频率)、滤波器类型(低通、带通滤波器)、运算放大器的讨论(用运算放大器设计的一级、二级滤波器、电路串联级联设计)、几种典型的滤波器(Butterworth、Chebyshev滤波器、设计中的频率转变、无源LC梯形滤波器的灵敏度设计、和开关电容滤波器做简短的介绍)。
6.操纵理论那个单元是教学关于持续、线性时不变系统的反馈操纵的应用,要求学生具有线性系统理论和拉普拉斯变换的基础。
学习的要紧目的是使学生在大体理论和进一步研究的能力方面打下一个坚实的基础,那个单元的学习将增进学生在本领域的进一步学习和尔后在工业操纵行业的工作。
本课程要紧内容包括操纵理论的历史、物理进程的模块化方式、时域系统的设计方式、用根轨迹法的设计方式、频率响应,和单一输入/输出系统状态方程设计方式的介绍。
7.微处置系统当前,运算机及微处置器在电子工业的各个领域中应用十分普遍。
随着运算机变得加倍复杂和功能壮大,微处置器的应用将持续快速增加。
对日趋增加的电子工业来讲,一个具有微处置器编程能力的学生将会有效武之地。
那个模块安排学生对一个简单的微处置器进程来完成工业上典型的操纵任务。
用汇编语言和C语言对微处置器进行编程,学生将用到一些内部的器件如RS232接口、按时器、中断器件、计数器、输入/输出口、模/数转换器等,利用这些器件通过编程完成操纵系统等操作。
8.运算机编程及其在工程中的应用此课程将继续介绍更高级的编程技术,教学中采纳C语言,重点放在如何运用编程技术解决工程应用的实际问题。
第二课电子元器件Ⅰ一、课文习题参考答案Ⅰ.(1)linear device (2)placed in parallel with a voltage source(3)discharge (4)component testing(5)insulation resistanceⅡ.(1)欧姆定律(2)最大功率损耗(3)非极性电容(4)交流阻抗(5)电容器的电容量可用电容器电桥测量(6)电压分压器Ⅲ.(1) Resistance is the opposition to the flow of current and is represented by the letter symbol R. The unit of resistance is the Ohm(Ω).(2)One Ohm is defined as that amount of resistance that will limit the current in a conductor to one ampere when the voltage applied to the conductor is one volt.(3)If a circuit contains resistance in series, the total resistance can be calculated by adding all the individual resistance. The formula isRT=R1+R2+R3+…+RnWhere RT is the total resistance, R1 through Rn are the individual resistance.(4) An inductor is an electrical device which can temporarily store electromagnetic energy in the field. The inductor is a coil of wire that may have an air core of an iron core to increase its inductance.A powered iron core in the shape of a cylinder may be adjusted in and out of the core.An inductor tends to oppose a change in electrical current, it has no resistance to DC current but has an AC resistance to AC frequency and is given by the formula XL=2πfLL, with units of ohms. Inductors are used for filtering AC current. It is electrically opposite to the capacitor. Its value is expressed in Henry (more commonly milliHenries). There are two major types of inductors, air core and iron core.(5) Methods for testing components are described below.Resistors are normally checked with an ohmmeter (in all probability on one of the resistance ranges of a multimeter). Such an instruments carries its own power supply and the circuit under test must be disconnected from the subunit power supply if the resistor is only partially removed from the circuit (that is, one end disconnected). Zero resistance on an ohmmeter is normally full scale deflection of the pointer and care must be taken not to confuse this reading with “infinite ohms”. With the meter leads connected together, the ohmmeter is first zeroed, using the electrical control provided. This removes lead resistance from the leading and adjust the zero control appropriate to the chosen range.Capacitors may also be checked for component resistance by use of an ohmmeter. On connection the meter initially reads low. Then capacitor is functional, the pointer moves to the high resistance end of the scale as the component charges. The reading given when the pointer stops moving is the insulation resistance, which is normally high if the capacitor is in good condition. Low resistance indicates a short circuit or a leaky capacitor. Very high resistance indicated immediately (that is, without charging) may indicate an open circuit except for very low value capacitors in which the charging time is too short to cause detectable pointer movement as described. Capacitance itself may be measured on a capacitor bridge. The instructions for use of these instruments depend upon the type and are usually given with the instrument.Inductors may be checked with an ohmmeter in the manner described for resistors, bearing in mind that inductor DC resistance is usually low. Inductance itself may be measured either by using a reliable AC supply to determine the inductive reactance or by a direct reading from a bridge instrument constructed for the purpose.二、参考译文电阻器、电容器和电感器组成了电子电路的重要元件。