作者：陈汝军
出版社：电子工业出版社
格式: AZW3, DOCX, EPUB, MOBI, PDF, TXT
电子通信专业英语试读：
前言
随着科学技术的发展，电子、通信各专业所涉及的内容相互渗透、相互包含，所以电子、通信各专业学生应该了解相关专业的知识。为了适应我国电子、通信、信息产业的飞速发展，了解其最新动态，提高从事相关专业的教学、科研、工程技术人员的专业英语水平，使他们能熟练地阅读和翻译有关英文文献、资料和书籍，特编写了本教材。
全书共分两部分：第一部分为电子、通信专业公共专业基础课（电路分析、模拟电路、数字电路等）；第二部分为通信专业课（通信原理、通信系统、卫星通信、光纤通信等）。书中对较为难懂的单词、短语给出了中文释义，对课文中较难的句子给出了参考译文，并在文章后面配有一定量的练习题，便于读者对文章内容的理解和掌握。在不影响阅读的前提下，部分文中提到的图表从略。
本教材各专业在安排教学时，可选择15课左右的专业基础课内容，15课左右专业课内容，剩余各课内容可安排作为学生课外阅读材料。本教材估计教学时数为50～60学时。
通过对本书的学习，可以使读者掌握和扩大专业英语词汇量及术语，了解科技文献的表达特点，提高阅读和理解原始专业英语文献的能力，掌握英语翻译技巧。有助于提高读者的阅读能力和开阔读者的视野。
本书由陈汝军担任主编，黄橙、田瑞利和刘小娟参加了部分内容的编写及资料收集工作。在编写和出版过程中，我们得到了本校通信专业教师的关心和支持，在此，向他们表示衷心的感谢。同时，我们也对引用的国内外高等院校的教科书和一些高级别的专业技术刊物的文章的作者表示感谢。
本书在专业内容的涵盖范围和语言的难易程度上也许会有不尽如人意的地方，书中也会有一些错误和不足之处，希望读者指正并提出宝贵的意见，以便今后改进。
编 者
2012年3月Lesson1 Brief Introduction to GMDSS
In November 1988 a decade of work reached a successful conclusion when a conference held at IMO headquarters adopted amendments to the SOLAS Convention and its 1978 Protocol.The amendments were intended to introduce GMDSS into the convention.The date chosen for entry into force，under the SOLAS "tacit acceptance" provisions，was 1st February 1992.
The basic concept of the system is that search and rescue authorities ashore，as well as shipping in the immediate vicinity of the ship in distress，will be rapidly alerted to a distress incident so they can assist in a coordinated search and rescue operation with the minimum delay.
The system will also provide for urgency and safety communications and the dissemination of maritime safety information（MSI），including navigational and meteorological warnings.In other words，every ship will be able，irrespective of the area in which it operates，to perform those communication functions considered essential for the safety of the ship itself and of other ships operating in the same area.
Although satellites will play an important part in GMDSS，they will not completely replace existing terrestrial radio.GMDSS combines various sub-systems which all have different limitations with respect to coverage into one overall system and the oceans are divided into four areas：
Area A1：within range of shore-based VHF coast stations（20～30 miles）；
Area A2：within range of shore-based MF coast stations（excluding A1 areas，in the order of 100 miles）；
Area A3：within the coverage area of geostationary maritime communication satellites（excluding A1 and A2 areas，approximately between 70°N and 70°S）；
Area A4：the remaining sea areas outside areas Al，A2 and A3.
The most important of these is the sea around the North Pole（the area around the South Pole is mostly land）.Geostationary satellites，which are positioned above the equator，cannot reach this far.
In all areas of operation the continuous availability of alerting should be provided.
Equipment requirements vary according to the area（or areas）in which the ship operates.Coastal vessels，for example，will only have to carry minimal equipment if they do not operate beyond the range of shore-based VHF radio stations.Ships which go further from land will have to carry MF equipment as well as VHF.Ships which operate beyond MF range will have to carry HF or INMARSAT equipment in addition to VHF and MF.Ships which operate in area A4 will have to carry HF，MF and VHF equipment.
In addition to radio equipment，GMDSS will introduce requirements for other equipment designed to improve the chances of survival.This includes EPIRBs and radar transponders for location of the ship or survival craft in distress.
Basically，GMDSS has seven functions，namely：1.alerting（from ship-to-ship，ship-to-shore，and shore-to-ship directions）；2.search and rescue coordinating communications；3.on-scene communications；4.locating；5.promulgation of maritime safety information；6.general radiocommunications；7.bridge-to-bridge communications.
The GMDSS consists of satellite communications and terrestrial communications.The use of satellite communications to improve maritime safety is particularly important for the introduction of global system and for establishing a reliable communication network.
Satellite communications will be used in both ship-to-shore and shore-to-ship directions.The INMARSAT satellite system，which employs geostationary satellites and operates in 1.5 and 1.6 GHz frequency bands，will provide a means of alerting from ships by using ship earth stations（SES）or satellite EPIRBs and a capability for two-way communications using radiotelex and optionally radiotelephone.Broadcast of maritime safety information to ships using radiotelex will also be provided through the INMARSAT system using either a standard ship station and associated equipment or dedicated facilities.A near polar-orbiting satellite EPIRB service（COSPAS-SARSAT system），operating in 406～406.1MHz frequency band，will provide a main means of distress alerting and determining the location of float-free EPIRBs operating through the system.Two types of shipborne equipment will be used for satellite communications：（1）ship earth stations，approved by INMARSAT；（2）satellite EPIRBs capable of being activated manually and of being activated automatically on floating free from a sinking ship.
The terrestrial communication comprises long-range service，medium-range service and shore-range service.HF will provide long-range service for use in the ship-to-shore and shore-to-ship directions.In areas covered by INMARSAT it can be used as an alternative to satellite communications and outside these areas it will provide the only long-range communications capability.Frequencies have been designated in 4，6，8，12 and 16MHz bands to provide means for transmitting and receiving distress alerts and safety calls and for passing distress and safety traffic.
Digital selective calling（DSC）will form the basis for distress alerting and safety calling.Coast stations participating in the HF distress and safety watch-keeping network will need to choose from five available frequency bands relaying an alert.The choice will depend on the position of the ship in distress，the geographical area to be alerted and the current propagation characteristics.It is envisaged that ships equipped with the HF option will maintain a watch on 8MHz alerting frequency and one of the other dedicated HF frequencies.The latter will be the frequency most appropriate to the area in which the ship is sailing.
Distress and safety communications following DSC calling will be performed by radiotelephony or narrow-band direct-printing（NBDP）or both.
A medium-range service will be provided on frequencies in 2MHz band.In the ship-to-shore，ship-to-ship and shore-to-ship directions，2187.5kHz will be used for distress alerts and safety calls by DSC，and 2182kHz will be used for distress and safety traffic by radiotelephony，including SAR coordinating functions and on-scene communications.2174.5kHz will be used for distress and safety traffic by radiotelex（NBDP）.
Frequencies near 500kHz will be used in the shore-to-ship direction.The frequency 518kHz will be used to transmit navigational and meteorological warnings in NAVTEX system.
VHF will provide a short-range service on following frequencies：（1）156.525MHz（channel 70）for distress alerts and safety calls by DSC；（2）156.8MHz（channel 16）for distress and safety traffic by radiotelephony，including SAR coordinating functions and on_scene communications.
New words and expressions
activate n.触发，激活vt.激活，启动
adopt vt.采用，通过
alert n.报警信号，警报，警告vt.提醒，报警
alternative n.替换a.选择的，二选一的
amendment n.修正案，修改，修正
appropriate a.适当的
approve vt.认可，赞同
area n.海区，地区，面积
associated a.有关的
automatically adv.自动地
availability n.可行性，有效性，可用性
available a.可行的，可用的，适用的，有效的
basically adv.基本上
bridge n.驾驶台
broadcast n.广播vt.广播
call n.呼叫vt.呼叫
capability n.能力，容量
carry vt.搬运，配备
characteristic a.特性的，特有的，特征的n.特性，特征
choice n.选择
choose vt.选择
coastal a.海岸的，沿海的
combine n.结合vi.组合为（into）vt.联合，结合
convention n.公约，约定
coordinate vt.协调，使……对等a.同等的，同位的n.坐标
cover n.封皮，覆盖，覆盖物vi.覆盖vt.包庇，覆盖，盖上
coverage n.覆盖区，覆盖
craft n.船，飞机，技能，技艺
current a.当前的，流行的n.电流，水流
decade n.十年，年代
dedicated a.专用的
depend on vt.取决于，依靠，依赖
designate vt.认定，指定
determine vt.决定，确定
dissemination n.传播，发布
employ n.雇用，占用vt.雇用，使用
entry into force 生效
envisage vt.面对，设想
equator n.赤道
equipment n.设备，装备，装置
essential a.本质的，必需的，基本的，主要的
exclude vt.不含，排斥，排除
existing a.存在的，现行的
facilities n.设备，设施
float vi.漂浮vt.浮
form vt.形成
frequency band n.频带，频段，频率波段
function n.功能，函数
geographical a.地理的
geostationary a.地球同步的，对地同步的
headquarters n.总部
improve vt.改善，提高
in addition to prep.除了……之外
in other words 换句话说，换言之
in the order of 大约
in the vicinity of…在……的附近
incident n.事故，事件
intend vi.打算vt.打算，意指
introduction n.引入，介绍
irrespective of 不管，不考虑
latter a.后面的，后者的n.后者
limitation n.局限性，期限，限度，限制
location n.定位，位置
maintain a watch on 8MHz 在8兆赫兹上保持收听
manually adv.手动地
maritime a.海的
means n.方法，工具，手段，资料
minimal a.最小（少）的，极小（少）的
namely adv.（that is，i.e.）即，就是
navigational and meteorological warnings 航行警告及气象警告
network n.网络
on-scene a.现场的
operate vt.航行，操作n.工作vi.操作
operation n.操作，运行，航行
option n.任选
optionally adv.任选地
overall a.全部的，总的adv.全部地n.工作服
participate vi.参加vt.参与
pass n.传送，合格，通过，通行证vi.通过vt.通过
perform vi.执行vt.履行，实行，完成
position n.位置vt.位于，定位
promulgation n.发布，播发
propagation n.传播
protocol n.议定书，协议
provision n.供应，规定，条款
radiotelephone n.无线电话
radiotelephony n.无线电话（技术），无线电话学
radiotelex n.无线电传
reach a successful conclusion 取得成功的结论/结果
receive vi.收到vt.接收，收到，受理
relay n.中继vi.传播，接替vt.接替，转播
reliable a.可靠的
remain n.剩余vi.保持，继续是vt.剩余
replace n.取代vi.复位vt.取代
requirement n.配备，必要条件，需要，要求
sail n.船只，帆船，航程vi.航行，启航
search and rescue authority ashore 岸上搜救机构
service n.服务，维护，维修，业务vt.保养
shipborne a.船载的
shipping n.船舶，海运，水运
shore-based a.岸基的
sink vi.沉没
subsystem n.分系统，子系统
survival n.生存，生存者vt.生存
tacit a.默认的，心照不宣的，不言而喻的
terrestrial a.地面的，地球的n.地球上的人
the ship in distress 遇险船
to play an important part in…在……中起着重要的作用
traffic n.交通，通信vt.经营，通信
transmit vt.传输，发射
transponder n.应答器
watchkeeping n.值班
with respect to adv.关于，就……而论
with the minimum delay 最短延时
within range of…adv.在……的范围内
Abbreviations in the text
COSPAS（俄）-SARSAT（near polar-orbiting search and rescue satellite system）n.近极轨道搜救卫星系统
DSC（digital selective calling）n.数字选择性呼叫
EPIRB（emergency position indicating radio beacon）n.应急无线电示位标
GHz（giga hertz）n.千兆赫
GMDSS（global maritime distress and safety system）n.全球海上遇险及安全系统
HF（high frequency）n.高频
IMO（international maritime organization）n.国际海事组织
INMARSAT（international maritime satellite organization）国际海事卫星组织；（international mobile satellite organization）国际移动卫星组织
kHz（kilo hertz）n.千赫
MF（medium frequency）n.中频
MHz（mega hertz）n.兆赫
MSI（maritime safety information）n.海上安全信息
NBDP（narrow band direct printing）n.窄带直接印字电报
SAR（search and rescue）n.搜救
SES（ship earth station）n.船舶地球站
SOLAS（safety of life at sea）n.海上人命安全公约
VHF（very high frequency）n.甚高频
Notes to the text
1.amendments to the SOLAS convention and its 1978 Protocol 关于SOLAS公约及其1978议定书的修正案（介词短语作后置定语）
2.The date chosen for entry into force（我们）选择的生效日期（过去分词短语作后置定语）
3.irrespective of the area in which it operates 不管其航行的海区
4.those communication functions considered essential for the safety of the ship itself and of other ships operating in the same area 我们认为对船舶自身安全及其航行于同一海区的其他船舶的安全都非常重要的那些通信功能（过去分词短语作后置定语）
5.various subsystems which all have different limitations with respect to coverage 关于覆盖范围都有不同限制的各种子系统（定语从句作后置定语）
6.Ships which go further from land离开大陆更远航行的船舶
7.requirements for other equipment designed to improve the chances of survival（我们）设计以提高生存机会的其他设备要求
8.The use of satellite communications to improve maritime safety 为了改善航海安全的卫星通信的使用（不定式短语作后置定语）
9.which employs geostationary satellites and operates in 1.5 and 1.6 GHz frequency bands 采用静止卫星且工作于1.5及1.6 GHz频带（L波段）
10.Broadcast of maritime safety information to ships using radiotelex will also be provided through the INMARSAT system using either a standard ship station and associated equipment or dedicated facilities.我们还将用无线电传方式通过INMARSAT系统用标准船站及相关设备或专用设备来提供对船广播海上安全信息。
11.A near polar-orbiting satellite EPIRB service（COSPAS-SARSAT system），operating in 406～406.1MHz frequency band 工作于406～406.1MHz频带的近极轨道卫星EPIRB业务（COSPAS-SARSAT系统）（现在分词短语作后置定语）
12.Coast stations participating in the HF distress and safety watch-keeping network 参与高频遇险及安全值守网络的海岸电台
13.the geographical area to be alerted 将要报警的地理海区
14.ships equipped with the HF option配备高频设备的船舶
15.Distress and safety communications following DSC calling DSC呼叫之后的遇险和安全通信
Exercises
一、将下列单词、词组或短语译成英文。
1.国际海事组织 2.修正案 3.海上人身生命安全公约 4.全球海上遇险及安全系统
5.岸上搜救主管部门 6.通信 7.海上安全信息发布 8.无线电 9.甚高频
10.高频 11.中频 12.国际移动卫星组织 13.设备 14.应急指位无线电示位标
15.卫星通信 16.地面通信 17.静止卫星 18.船舶地球站 19.千赫兹/兆赫兹
20.窄带直接印字电报 21.频率 22.无线电报 23.无线电话 24.网络 25.频带
二、将下列句子译成中文。
1.The date chosen for entry into force，under the SOLAS "tacit acceptance" provisions，was 1st February1992.
2.Although satellites will play an important part in GMDSS，they will not completely replace existing terrestrial radio.
3.Ships which operate beyond MF range will have to carry HF or INMARSAT equipment in addition to VHF and MF.
4.The terrestrial communication comprises long-range service，medium-range service and shore-range service.
5.Distress and safety communications following DSC calling will be performed by radiotelephony or narrow-band direct-printing（NBDP）or both.
三、将下列句子译成英文。
1.GMDSS系统不仅能完成遇险及安全通信，而且还能完成常规通信。
2.GMDSS系统由卫星通信系统及地面通信系统构成，并且具有七大功能。
3.卫星通信系统在未来的通信中将起着非常重要的作用。
4.船舶通信设备的配备是由其航行的海区确定的。
5.频率的单位是赫兹，常用的有：赫（兹）、千赫（兹）、兆赫（兹）及千兆赫（兹）等。Lesson2 Charge，Current and Voltage
One of the most fundamental concepts in electric circuit analysis is charge conservation.We know from basic physics that there are two types of charge：positive（corresponding to a proton），and negative（corresponding to an electron）.For the most part，this text is concerned with circuits in which only electron flow is relevant.There are many devices（such as batteries，diodes，and transistors）in which positive charge motion is important to understanding internal operation，but external to the device we typically concentrate on the electrons which flow through the connecting wires.Although we continuously transfer charges between different parts of a circuit，we do nothing to change the total amount of charge.In other words，we neither create nor destroy electrons（or protons）when running electric circuits.Charge in motion represents a current.
In the SI system，the fundamental unit of charge is the coulomb（C）.It is defined in terms of the ampere by counting the total charge that passes through an arbitrary cross section of a wire during an interval of one second；one coulomb is measured each second for a wire carrying a current of 1 am-pere.In this system of -19units，a single electron has a charge of-1.602×10 C and a single -19proton has a charge of+1.602×10 C.
A quantity of charge that does not change with time is typically represented by Q.The instantaneous amount of charge（which may or may not be time-invariant）is commonly represented by q（t），or simply q.This convention is used throughout the remainder of the text：capital letters are reserved for constant（time-invariant）quantities，whereas lowercase letters represent the more general case.Thus，a constant charge may be represented by either Q or q，but an amount of charge that changes over time must be represented by the lowercase letter q.
The idea of "transfer of charge" or "charge in motion" is of vital importance to us in studying electric circuits because，in moving a charge from place to place，we may also transfer energy from one point to another.The familiar cross-country power-transmission line is a practical example of a device that transfers energy.Of equal importance is the possibility of varying the rate at which the charge is transferred in order to communicate or transfer information.This process is the basis of communication systems such as radio，television，and telemetry.
The current present in a discrete path，such as a metallic wire，has both a numerical value and a direction associated with it；it is a measure of the rate at which charge is moving past a given reference point in a specified direction.
Once we have specified a reference direction，we may then let q（t）be the total charge that has passed the reference point since an arbitrary time t=0，moving in the defined direction.A contribution to this total charge will be negative if negative charge is moving in the reference direction，or if positive charge is moving in the opposite direction.
We define the current at a specific point and flowing in a specified direction as the instantane ous rate at which net positive charge is moving past that point in the specified direction.This，unfortunately，is the historical definition，which came into popular use before it was appreciated that current in wires is actually due to negative，not positive，charge motion.Current is symbolized by I or i，and so
The unit of current is ampere（A），named after A.M.Ampere，a French physicist.It is commonly abbreviated as an "amp"，although this is unofficial and somewhat informal.
Using Eq.（2.1），we compute the instantaneous current.The use of the lowercase letter "i" is again to be associated with an instantaneous value；an uppercase "I" would denote a constant（i.e.，time-invariant）quantity.
The charge transferred between time t and t may be expressed 0as a definite integral：
The total charge transferred over all time is obtained by adding q（t），the charge transferred up to the time t，to the preceding 00expression：
There are several different types of current.A current that is constant in time is termed a direct current，or simply DC.We will find many practical examples of currents that vary sinusoidally with time；currents of this form are present in normal household circuits.Such a current is often referred to as alternating current，or AC.Exponential currents and damped sinusoidal currents will also be encountered later.
We establish a graphical symbol for current by placing an arrow next to the conductor.Thus，in Fig.2.1 the direction of the arrow and the value "3A" indicate either that a net positive charge of 3C is moving to the right or that a net negative charge of-3C is moving to the left each second.In Fig.2.2 there are again two possibilities：either-3A is flowing to the left or+3A is flowing to the right.All four statements and both figures represent currents that are equivalent in their electrical effects，and we say that they are equal.A nonelectrical analogy that may be easier to visualize is to think in terms of a personal savings account：e.g.，a deposit can be viewed as either a negative cash flow out of your account or a positive flow into your account.Fig.2.1Fig.2.2
It is convenient to think of current as the motion of positive charge，even though it is known that current flow in metallic conductors results from electron motion.In ionized gases，in electrolytic solutions，and in some semiconductor materials，positively charged elements in motion constitute part or all of the current.Thus，any definition of current can agree with the physical nature of conduction only part of the time.The definition and symbolism we have adopted are standard.
It is essential that we realize that the current arrow does not indicate the "actual" direction of current flow but is simply part of a convention that allows us to talk about "the current in the wire" in an unambiguous manner.The arrow is a fundamental part of the definition of a current！Thus，to talk about the value of a current i（t）without lspecifying the arrow is to discuss an undefined entity.For example，Fig.2.3 and Fig.2.4 are meaningless representations of i（t），lwhereas Fig.2.5 is the proper definitive symbology.Fig.2.3Fig.2.4Fig.2.5
We must now begin to refer to a circuit element，something best defined in general terms to begin with.Such electrical devices as fuses，light bulbs，resistors，batteries，capacitors，generators，and spark coils can be represented by combinations of simple circuit elements.We begin by showing a very general circuit element as a shapeless object possessing two terminals at which connections to other elements may be made.
There are two paths by which current may enter or leave the element.In subsequent discussions we will define particular circuit elements by describing the electrical characteristics that may be observed at their terminals.
In Fig.2.6，let us suppose that a DC current is sent into terminal A，through the general element，and back out of terminal B.Let us also assume that pushing charge through the element requires an expenditure of energy.We then say that an electrical voltage（or a potential difference）exists between the two terminals，or that there is a voltage "across" the element.Thus，the voltage across a terminal pair is a measure of the work required to move charge through the element.The unit of voltage is volt，and 1 volt is the same as 1 J/C.Voltage is represented by V or v.
A voltage can exist between a pair of electrical terminals whether
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