信息科学与电子工程专业英语（第2版）

本教材可供高等院校信息科学、通信工程、电子技术、计算机应用等专业的本科生和研究生学习专业英语之用，亦可供广大英语学习爱好者参考。本书选材兼顾经典题材和新兴技术，在编写中力求改革创新，强调大量实践，注重培养学生以较高准确性和足够的速度阅读专业资料和文献的能力，兼顾一定的专业英语表达能力。全书共18单元，各单元包括课文、词汇、难点注释、课外阅读资料、习题。课文内容涉及电子技术、通信工程、信息处理、计算机应用等领域的基础知识和新技术进展，每一单元包括2～3篇科技文章或技术资料。对部分科技术语和重要概念提供简要的英文辅助资料，以便于理解课文，并在学习科技英语的同时扩大专业知识面。书后附有关于科技英语阅读、写作、克服中式英语等问题的指南和讨论。 

本书供高等院校信息科学、通信工程、电子技术、计算机应用等专业的本科生和研究生学习专业英语之用。选材兼顾经典题材和新兴技术，在编写中摈弃过分依赖语法、死记硬背的陈旧教学方法，注重培养学生以较高准确性和足够的速度阅读专业资料和文献的能力，兼顾一定的专业英语表达能力，从阅读、翻译、写作等角度提高学生对专业英语的应用能力。
　　全书共17单元，各单元包括课文、词汇、难点注释、课外阅读资料、习题。书后附有关于科技英语阅读、写作、克服中式英语等问题的指南和讨论。

Unit 1  Electronics: Analog and  Digital    1
Text    1
Part I: Ideal Operational Amplifiers and Practical Limitations    1
Part II: Data Registers and Counters    3
Part III: Nature of Phase Lock    6
New Words    8
Notes on the Text    9
Technical Tips    12
Supplementary Readings: Bridging the Gap between the
Analog and Digital Worlds    13
Exercises    17
Unit 2  Integrated Circuits    21
Text    21
Part I: The Integrated Circuit    21
Part II: Application Specific Integrated Circuit    24
New Words    27
Notes on the Text    28
Technical Tips    31
Supplementary Readings    31
Exercises    34
Unit 3  EM Fields, Antenna and Microwaves    37
Text    37
Part I: Electromagnetic Field    37
Part Ⅱ: Microstrip Antenna    38
Part Ⅲ: Microwaves    40
New Words    43
Notes on the Text    44
Technical Tips    46
Supplementary Readings: What Are Microwaves?    46
Exercises    50
Unit 4  Communication and Information Theory    53
Text    53
Part I: Telecommunication    53
Part Ⅱ: Data Transmission    55
Part Ⅲ: Information Theory    56
New Words    59
Notes on the Text    60
Technical Tips    63
Supplementary Readings    63
Exercises    66
Unit 5  Multiple Access Techniques    70
Text    70
Part I: Multiple Access Techniques: FDMA, TDMA and CDMA    70
Part Ⅱ: Orthogonal Frequency Division Multiplexing    76
New Words    79
Notes on the Text    80
Technical Tips    82
Supplementary Readings: Wavelength-Division  Multiplexing    82
Exercises    85
Unit 6  Mobile Communications    88
Text    88
Part I: Mobile Communications    88
Part Ⅱ: Fourth Generation Wireless Networks    91
New Words    94
Notes on the Text    95
Technical Tips    97
Supplementary Readings: The Road to 5G    98
Exercises    102
Unit 7  Optical Communications    104
Text    104
Part I: Electromagnetic Spectrum    104
Part Ⅱ: Optical Fiber    107
New Words    111
Notes on the Text    112
Technical Tips    115
Supplementary Readings: Optical Systems    116
Exercises    119
Unit 8  Digital Signals and Signal Processing    122
Text    122
Part I: Digital Signal Processing    122
Part Ⅱ: General Concepts of Digital Signal Processing    125
New Words    130
Notes on the Text    132
Technical Tips    134
Supplementary Readings: Designing Digital Filters    135
Exercises    141
Unit 9  Digital Audio Compression    145
Text    145
Part I: MPEG Audio Layer 3    145
Part Ⅱ: Digital Audio Compression Standard AC3    147
New Words    151
Notes on the Text    152
Technical Tips    154
Supplementary Readings: Audio Compression Algorithm Overview    155
Exercises    159
Unit 10  Digital Image Processing    162
Text    162
Part I: Two-Dimensional Digital Images    162
Part Ⅱ: Digital Images ? Definition and Applications    164
Part Ⅲ: Introduction to Image Processing    167
New Words    172
Notes on the Text    174
Technical Tips    180
Supplementary Readings    180
Exercises    186
Unit 11  Biometrics Technology    188
Text    188
Part I: Fingerprint Identification    188
Part Ⅱ: Introduction to Speaker Identification    190
New Words    195
Notes on the Text    196
Technical Tips    199
Supplementary Readings: Biometrics Overview    200
Exercises    204
Unit 12  Information Security    207
Text    207
Part I: Information Security — Introduction and a Brief History    207
Part Ⅱ: Basic Principles of Information Security    208
Part Ⅲ: Intrusion Detection System    210
New Words    212
Notes on the Text    214
Technical Tips    217
Supplementary Readings: Hidden Communication    218
Exercises    223
Unit 13  Telemedicine and Biomedical Signal Processing    226
Text    226
Part I: Telemedicine    226
Part Ⅱ: Computerized Tomographic Imaging    228
New Words    230
Notes on the Text    231
Technical Tips    234
Supplementary Readings: Biomedical Signal  Processing    234
Exercises    237
Unit 14  Computers and Networks    240
Text    240
Part I: Evolution of Computers    240
Part Ⅱ: Local Area Networks    244
New Words    249
Notes on the Text    250
Technical Tips    253
Supplementary Readings    254
Exercises    258
Unit 15  Artificial Intelligence    262
Text    262
Part I: What Is Artificial Intelligence    262
Part Ⅱ: Approaches of AI    264
New Words    268
Notes on the Text    269
Technical Tips    271
Supplementary Readings: AlphaGo    272
Exercises    275
Unit 16  Big Data and Cloud Computing    278
Text    278
Part I: Big Data    278
Part Ⅱ: Cloud Computing    282
New Words    286
Notes on the Text    287
Technical Tips    289
Supplementary Readings: Smart City    290
Exercises    294
Unit 17  Internet of Things (IoT)    296
Text    296
Part I: Internet of Things: Concept and Key Technologies    296
Part Ⅱ: IoT Applications    299
New Words    303
Notes on the Text    304
Technical Tips    306
Supplementary Readings: Wireless Sensor Network    307
Exercises    310
Appendices    312
I. How Should We Read English    312
Ⅱ. Writing Technical English    314
Ⅲ. Avoid Pidgin English    329
Ⅳ. Title of Scientific Papers    337
Ⅴ. How to Write Abstract    339
Bibliography    343

本教材是为信息科学、通信工程、电子技术、计算机应用等专业的本科生、研究生学习科技英语而编写的。本书选材力求覆盖较广泛的专业方向，注重经典题材和新兴技术，对部分基本原理或新概念提供相关英文辅助资料，以便教师结合课文有选择地用英语讲述一些专业基础知识，或者供学生阅读，使他们在学习科技英语的同时扩大专业知识面。
　　英语是理工科学生必须掌握的实用工具。然而，不少学生在学了十多年英语以后，仍不能有效地运用英语获取专业知识和科技信息，更不要说用英语进行科技交流了。根据这种情况，结合大学英语教学现状，我们在本书编写中力求改革创新，拒绝应试教学，摈弃从语法到语法、死记硬背的陈旧教学方法，强调大量实践，主张阅读准确性和阅读速度并重，兼顾英语表达能力的提高。
　　我们认为大学高年级和研究生专业英语教学应以培养和提高英语运用能力为根本目的。学生并不缺少语法知识，而是缺少实践。他们很少甚至没有读过科技英语资料，不掌握丰富的表达形式，缺乏正确的语感。我国学生语法基础普遍较好，但在阅读中往往过分依赖语法分析。他们不了解语法的作用应是内在的和深层的，而不是表面的。依赖语法分析不仅阅读速度上不去，而且即使看懂了句子，读完全文可能还抓不住要点。这种现象相当普遍。实际上，理工科学生学外语并不是为了研究语言，而是要运用语言，因此应以感性认识和反复实践为主，语法知识学习为辅。基于这一认识，我们在课文注释中尽量避免使用语法术语，希望学生在阅读实践中提高阅读能力，终甩掉语法拐棍。只有这样才能逐步做到顺序阅读而不用回头看，达到理解准确性和阅读速度的统一。
　　写作不是本教材的重点，但阅读能力的突破以及在阅读中的留心观察，对于写作能力的形成和提高具有关键性的作用。附录中收入了我们在科技英语阅读和写作方面的体会，其中包括一些探索性的研究心得和观点。此外，我们还讨论了普遍存在的中式英语问题，根据大量实例分析了一些典型情况，并就如何克服中式英语提出我们的看法，供读者参考并希望得到专家的指导。
　　本书是2008年版《信息科学与电子工程专业英语》的第2版，扩大了适用范围，充实了近年来如物联网、大数据、云计算等热点技术及其应用的内容，力求通过范文的阅读和翻译，培养学生以较高准确性和足够的速度阅读专业资料的能力，同时使学生通过学习科技英语的用词、句型和语言风格，提高专业英语写作和表达的应用能力。
　　本教材反映了教学小组全体教师多年来在教学中积累的经验，编者特别要感谢陈泉林、石海、朱秋煜、石旭利、李颖洁老师所提供的帮助和支持。
　　因编者水平所限，书中不当之处在所难免，敬请读者不吝指正。
　　
                                       编者
　　　　　　　　　　　　　　　　　　　　　　2017年10月

Multiple Access Techniques
　　Today the rapidly increasing communications systems are operating in an increasingly crowded frequency spectrum. The only solution appears to be sharing the precious frequency resources among different users, and there comes the need for developing various multiple access techniques.   
Text
Part I: Multiple Access Techniques: FDMA, TDMA and CDMA
　　Multiple access schemes are used to allow many simultaneous users to use the same fixed bandwidth radio spectrum. In any radio system, the allocated bandwidth is always limited. For mobile phone systems the total bandwidth is typically 50MHz, which is split in half to provide the forward and reverse links of the system. Sharing of the spectrum is required in order to increase the user capacity of any wireless network. FDMA, TDMA and CDMA are the three major methods of sharing the available bandwidth to multiple users in wireless system. There are many extensions, and hybrid techniques for these methods, such as OFDM, and hybrid TDMA and FDMA systems. However, an understanding of the three major methods is required for understanding of any extensions to these methods.
　　Frequency division multiple access
　　In Frequency Division Multiple Access (FDMA), the available bandwidth is subdivided into a number of narrower bands. Each user is allocated a unique frequency band in which to transmit and receive. During a call, no other user can use the same frequency band. Each user is allocated a forward link channel (from the base station to the mobile phone) and a reverse channel (back to the base station), each being a single way link. The transmitted signal on each of the channels is continuous allowing analog transmissions. The bandwidths of FDMA channels are generally low (30 kHz) as each channel only supports one user. FDMA is used as the primary breakup of large allocated frequency bands and is used as part of most multi-channel systems. Figures 5.1 and 5.2 show the allocation of the available bandwidth into several channels.

Figure 5.1  FDMA showing that the each narrow band channel is allocated to a single user

Figure 5.2  FDMA spectrum, where the available bandwidth is subdivided into narrower band channels
　　Time division multiple access
　　Time Division Multiple Access (TDMA) divides the available spectrum into multiple time slots, by giving each user a time slot in which they can transmit or receive. Figure 5.3 shows how the time slots are provided to users in a round robin fashion, with each user being allotted one time slot per frame.1

Figure 5.3  TDMA scheme where each user is allocated a small time slot
　　TDMA systems transmit data in a buffer and burst method, thus the transmission of each channel is non-continuous. The input data to be transmitted is buffered over the previous frame and burst transmitted at a higher rate during the time slot for the channel.2 TDMA cannot send analog signals directly due to the buffering required, thus is only used for transmitting digital data. TDMA can suffer from multipath effects as the transmission rate is generally very high. This leads the multipath signals causing inter-symbol interference.
　　TDMA is normally used in conjunction with FDMA to subdivide the total available bandwidth into several channels. This is done to reduce the number of users per channel allowing a lower data rate to be used. This helps reduce the effect of delay spread on the transmission. Figure 5.4 shows the use of TDMA with FDMA. Each channel based on FDMA, is further subdivided using TDMA, so that several users can transmit over one channel. This type of transmission technique is used by most digital second generation mobile phone systems. For GSM, the total allocated bandwidth of 25MHz is divided into 125 channels using FDMA, each having a bandwidth of 200 kHz. These channels are then subdivided further by using TDMA so that each 200 kHz channel allows 8～16 users.
 
Figure 5.4  TDMA/FDMA hybrid in which the bandwidth is split into frequency channels and time slots
　　Code division multiple access
　　Code Division Multiple Access (CDMA) is a spread spectrum technique that uses neither frequency channels nor time slots. In CDMA, the narrow band message (typically digitized voice data) is multiplied by a large bandwidth signal which is a pseudo random noise code (PN code). All users in a CDMA system use the same frequency band and transmit simultaneously. The transmitted signal is recovered by correlating the received signal with the PN code used by the transmitter. Figure 5.5 shows the general use of the spectrum using CDMA.

Figure 5.5  Code division multiple access (CDMA)
　　CDMA technology was originally developed by the military during World War Ⅱ. Researches were spurred into looking at ways of communicating that would be secure and work in the presence of jamming. Some of the properties that have made CDMA useful are:
* Signal hiding and non-interference with existing systems..
* Anti-jam and interference rejection.
* Information security.
* Accurate ranging.
* Multiple user access.
* Multipath tolerance.