电子信息类专业英语 李白萍编 第二版译文
第17章电子信息类专业英语(李白萍)
Unit Seventeen Others (Ⅱ)
On the other hand, in Europe, which consists of many small or medium countries, microwave systems in the network seems to be slightly less important. In many developing countries, microwave radio-relay systems play the key role in the network. It is quite logical because the microwave system has the following features: the initial investment required for the construction of transmission routes is low; the construction can be completed within a relatively short period; it is suitable for television transmission.
Unit Seventeen Others (Ⅱ)
Radio communication operating at medium or high frequencies was first applied to the fieldtime mobile and intercontinental communication, where its superiority was evident. It was only after the advent of microwave communication technology that it became possible for radio technology to be applied in full scale in the field where cable transmission had been dominant. Thus, the microwave radio-relay system using analogue modulation grew into a very important transmission medium in the overall telecommunications networks in many countries. Recently, a rapid advance in semiconductor and pulse circuit technologies gave impetus to the research and development of digital radio-relay systems.[2] There is now a marked trend that the telecommunication network is moving gradually towards digital systems.
Unit 19_The General System_通用系统_译文
电子信息类专业英语（第二版李白萍）Unit 19 Passage A The General System 译文19、光纤通信Passage A 通用系统通信杯广泛地定义为信息从一个点至另外一个点的传输。
当信息进行长距离传输时，通常需要一个通信系统。
在一个通信系统中信息的传输可以通过将信息叠加或者调制到作为信息信号的载体的电磁波上。
调制载波再传输到需要的接收端，并通过解调获得原始信号。
····然而，“通信”可以通过使用从光波范围内的频率选择的载频实现。
光纤通信系统与其他任何一类通信系统在基本概念上是相似的。
图19.1（a）是一个通用通信系统的方框图解，其功能是将信号从信息源节点通过传输媒介传递至目的地。
因此，通信系统包括与信息源相连接的发射器或调制解调器，传输媒介，以及终端的一个接收器或者解调器。
在电通信系统中，信息源提供由非电的信息信号转化而来（声音信号）的电信号，给包含电以及电子元件的发射器，发射器将信号转化为适合通过传输媒介传输的合适的形式。
这个过程通常是通过调制载波实现的。
正如上述所说，可能是电磁波。
传输介质可以是一对导线，同轴电缆或者是通过自由空间的无线电，经过传输媒介信号被传递至接收者，信号在传递到终端之前会被转化为原始的电信息信号。
然而，值得注意的是，信号在任何介质中都会衰减或遭到损失，并且会受到通信过程中随机信号以及噪声的损害，并且可能会受到传输媒介自身的机制带来的失真。
因此，在任何通信系统中在发射器以及接收器之间都有一个最大允许距离，超过这个距离，通信系统将会中断通信。
由于上述因素，对于长距离应用，需要（要求）按照一定的间隔安装中继器或者是线路放大器，这样不仅能够消除信号的失真并且能够增加信号电平，以使得沿着链路能够继续传输下去。
相较于图19.1（b）中所给定的图，图19.1（a）中给定的关于光纤通信系统的图可能考虑的更为详细。
在图中，信息源为发射器提供电信号，发射器包含一个电子平台以驱动光源调制光仔波。
电子信息专业英语(第二版)(李白萍)章 (16)
Unit 16 3rd Generation Mobile Communications · Outstanding Spectrum Efficiency increases
capacity. As already stated, with asymmetric traffic applications, TD-SCDMA utilizes the available spectrum more efficiently than other 3G standards since it employs only one band for both uplink and downlink traffic (TDD unpaired band) instead of two separate bands for uplink and downlink (FDD paired bands).［4］ Moreover, highly effective technologies like smart antennas, joint detection and dynamic channel allocation -which are integral features of the TDSCDMA radio standard-contribute to minimize intra-cell interference (typical of every CDMA technology) and inter-cell interference leading to an outstanding spectrum efficiency (3-5 times GSM). This is especially helpful in densely populated urban areas, which are
电子信息类专业英语第五单元译文 李白萍主编
电子信息类专业英语（第二版）李白萍主编第五单元译文第五单元A compact disc (CD) is a laser-read (also termed “optically read”) data storage device on which audio, video, or textual material can be stored. Although it has been used primarily to record stereophonic sound and has supplanted the long-playing PHONOGRAPH record as the principal medium for music storage, it offers a huge potential as the medium for the storage of massive amounts of many types of information.[1]一个光盘（CD）是在其上的音频，视频或文本材料可被存储在激光读取（也称为“光学读取”）数据存储设备。
虽然它被主要用来记录立体声声音，并已经取代了留声机成为了主要的音乐存储媒体，但它作为能存储大量多种信息的媒体仍具有巨大的潜力。
Unlike the conventional phonograph record, the CD stores information in digital form. Stereophonic (two-channel) sound signals are digitally sampled at a rate of 44,100 times per second per channel. Each sample is expressed as a binary number value consisting of 16 binary digits, or bits. The sampled digital values, along with error correction data, tracking codes, and cueing data, are recorded on a digital tape, which is used to make compression-molded plastic discs 12 cm (4.72in) in diameter, each covered by a thin, reflective metallic layer and protected by a clear plastic coating.[2] During playback, a low-powered laser beam reads the digital data through the reflective rear surface of the disk.[1]与传统的照片记录不同，光盘以数字形式存储的信息。
电子信息类专业英语 李白萍编 第二版译文
第19章B 光纤通信的优点利用一根玻璃光纤引导的光载波通信有许多突出的优点，其中的一些优点在最初构思这种技术时就已经显而易见了。
然而，当今的技术发展已经超越了当初最乐观的预测，产生了另外一些优势。
因此，有必要考虑光纤通信与许多传统电子通信相比带来的优点和专业特色。
本文先介绍最初预想的优点，接着介绍随着科技发展而出现的另外的突出优点。
a）巨大的潜在带宽：频率为1013到1016 Hz（通常接近大约1014Hz红外线的频率）的光载波产生比金属电缆系统（如同轴电缆的带宽最高为500MHz）甚至毫米波无线电系统（例如系统当前工作在700MHz调制带宽）大得多的潜在传输带宽。
目前，光纤系统可以用带宽并没有被完全利用，但是，不需要中继器而传输100Km的几Ghz的调制和传输300km的几百Mhz的调制是可能的。
光纤系统的信息携带能力远优于最好的铜电缆系统。
比较而言，宽带同轴电缆系统在100Mhz以上带宽内的损耗将传输距离限制在只有几千米的范围内。
虽然可以利用的光纤带宽可以被进一步扩展到光载波频率，但是很明显这一参数（可用带宽）被单个光载波信号所限制。
因此，通过在同一个光纤中并行传输几个工作在不同的中心波长的光信号可以实现带宽利用率的很大提高。
利用波分复用技术，尤其是密集波复用（或者说，实质上的频分复用）使得光纤的信息载容量超过电缆或者宽带无线系统好多个数量级。
b）小尺寸和轻重量：光纤的直径非常小，通常比头发丝的直径还要细。
因此，就算这些光纤被涂覆层包裹时，它们都要比铜电缆直径更小并且重量更轻。
这对于缓解城市的管道拥挤而言占有很大的优势，并且允许在移动体（如飞机、卫星甚至船舶）内进行信号传输。
c）电绝缘：由玻璃或者塑料聚合物制造的光纤是电绝缘体，因此与其他对应的金属物不同，它们不存在接地循环与接口问题。
而且，该优点使得光纤十分适宜于在对电子比较敏感的危险环境中的通信，因为光纤在受侵蚀或者短路的情况下不会产生电弧或者电火花的危险。
第4章电电子信息类专业英语(第二版)_李白萍
Unit Nine Microelectronics
Passage A Introduction to Microelectronics Passage B The Simple Atom, Conductors, Insulators and Semiconductors Passage C Diode and Transistor
Unit Nine Microelectronics
FET (Field effect transistors)场效应管 impedance 阻抗 dissipation 损耗 extractive 抽出; 释放出 fabrication 制造, 装配; 捏造事实 bias 偏差; 偏置 capacitor 电容 inductive 电感 dispense 分配 lumped element 集总元件 transistor 晶体管
Unit Nine Microelectronics
Most electronic circuits are composed of active devices, e.g. transistors and diodes, together with resistors (for bias, collector load, impedance transformation, etc.) and capacitors (e.g. for coupling ac signals while blocking dc supplies). Each of these elements can be produced in a form suitable for integrated circuit inclusion within limitations, e.g. capacitance values must not be too large. Some elements are difficult to produce in a suitable form, e.g. inductive elements, or large capacitors. Usually some alternative circuit form can be devised that dispenses with the requirement. Otherwise they must be included as an external lumped element.
第12章电子信息类专业英语(李白萍)
Unit Twelve DataBase
Unit Twelve DataBase
How does a database help to solve the data dependency problem? Since the responsibility for accessing the physical data rests with the database management system, the programmer can ignore the physical data structure.[1] As a result, programs tend to be much less dependent upon their data, and are generally much easier to maintain. Expect the trend toward database management to continue.
Unit Twelve DataBase
Why is this a problem? For one thing, different application often need the same data elements. For example, schools generate both bills and student grade reports. View the applications independently. The billing program reads a file of billing data, and the grade report program reads an independent file of grade data. The output of both programs are mailed to each other student’s home; thus, student names and addresses must be redundantly recorded on both files. What happens when a student moves? Unless both files are updated, one will be wrong. Redundant data are difficult to maintBase
电子信息类专业英语第二版 李白萍主编十七单元译文
电子信息类专业英语第二版李白萍主编第十七单元B译文Passage B Compression/Decompression Techniques压缩/解压缩技术Numerous methods have been developed for the compression of digital image data. One of the principal drivers for this development is the television industry where quality image data must be transferred to receivers using relatively simple equipment. The development of high definition television is further focusing the attention of industry and university scientists toward problems of data reduction and digital transmission. The principal evaluation criteria for the analysis of compressed versus uncompressed imagery is whether a person can tell the difference between the images. A more implemental measure is the Root Mean Square (RMS) error between the original image and the image that has been compressed. Compression rates may be generated by determining the size of the compressed image in terms of number of bits per image pixel for the original image.[1]数字图像数据的压缩的许多方法已经开发出来。