通信英语(第四版)张筱华-石方文-北京邮电大学出版社【课后习题答案】

1.PCM原理抽样量化与编码:sampling,quantizingandcoding话路:speechchannel幅值:amplitudevalue抽样频率抽样速率脉冲流:samplingfrequency:samplingrate:streamofpulses:repetitionrate:codingprocess重复率编码过程模拟信号:analogsignal传输质量:transmissionquality数字通信:digitalcommunication数字传输:digitaltransmission:noisyenvironment含噪声的环境传输路由:transmissionpath信噪比:signal-to-noiseratio信号电平:signallevels噪声功率:noisepower地面系统:terrestrialsystem二进制传输:binarytransmission反向操作:reverseoperation8-位码序列接受端:8-digitsequence:receivingterminal:frameformat帧格式同步字:synchronizationword实现这三项功能的方案:theschemesforperformingthesethreefunctions一串幅值:aseriesofamplitudevalues电话质量的话路aspeechchanneloftelephonequality一个8位二进制码的序列理论上的最小抽样频率:asequenceof8-binarydigits:aminimumtheoreticalsamplingfrequency占据着300Hz到3.4kHz频率范围的话路:avoicechanneloccupyingtherange300Hzto3.4kHz8-位码:8-digitspersamplevalue每个样值汽车点火系统的打火:thesparkingofacarignitionsystem重复率为64kHz的脉冲流:thestreamofthepulseswitharepetitionrateof64kHz真实信号与噪声信号的关系由卫星上接受到的信号一条特定消息中的全部信息被传信号的波形:relationshipofthetruesignaltothenoisesignal:thesignalreceivedfromasatellite:thecompleteinformatianaboutaparticularmessage:theshapeofthetransmittedsignal由传输路由引入的衰减:theattenuationintroducedbytransmissionpath将抽样的幅值转换成一串脉冲的单元pulses:theunitthatconvertssampledamplitudevaluetoasetof涉及到第一路，第二路及其他各路的序列被称为同步字的独特码序列:asequencerelatingtochannel1,2andsoon:auniquesequenceofpulsescalledsynchronizationword地面系统:terrestrialsystem脉冲的“有”或“无”:thepresenceorabsenceofthepulses

高速的电子开关时分多路复用器时分多路复用:ahigh-speedelectronicswitch:thetimedivisionmultiplexer:TimeDivisionMultiplexer2.异步串行数据传输串行接口serialinterfaceCRTterminal显示终端发送器与接收器数据传输transmitterandreceiverdatatransmission数据流datastream闲置状态传号电平空号电位theidlestatemarklevelspacelevel起始位startbit停止位stopbitT秒的持续时间奇偶校检位错误标志durationofTsecondsparitybiterrorflag传输错误transmissionerror下降沿fallinfedge符号间的空格接收机的定时本地时钟intersymbolspacereceivertiminglocalclock磁带magnetictape控制比特controlbit逻辑1电平logical1level二进制数据binarydata明显的缺点obviousdisadvantage异步串行数据传输最为流行的串行接口所传送的数据asynchronousserialdatatransmissionthemostpopularserialinterfacethetransmitteddata发送器与接收器的时钟电传机的时代theclocksatthetransmitterandreceivertheeraofteleprinter一个字符的点和划符号间空格持续时间的三倍被称为字符的比特组thedotsanddashsofacharacterthreetimesthedurationofintersymbolspacethegroupofbitscalledcharacters由7或8个比特的信息组成的固定单元由接收机本地产生的时钟theinvariableunitscomprising7or8bitsofinformationaclockgeneratedlocallybythereceiver在字符后所收到的奇偶校检位thereceivedparitybitfollowingthecharacterthefallingedgeofthestartbitthecharacter-orientednatureofthedatalink起始位的下降沿数据链路面向字符的特性3.数据通信地下电缆通信卫星微波设备undergroundcablecommunicationsatellitemicrowavefacilities

调制器与解调器缓冲器modulatoranddemodulatorbuffer定时信号timingsignals同步脉冲synchronizationpulses时隙timeslot移位寄存器传输媒体线形衰弱信息安全shiftregistertransmissionmediumlinearattenuationinformationsecurity键盘keyboard数据终端dataterminals某种类型的数据转换设备视频显示终端sometypeofdataconversionequipmentvisualdisplayterminal称为数据调制解调器的双向数据发送接收机全双工的数据传输系统two-waydatatransmistter-receivercalledadatamodemfull-duplexdatatrandmissionsystem由数据处理器的运算速率所决定的速率processortheratedeterminedbytheoperatingspeedofthedata由接口部件来的定时信号timingsignalsfromtheinterfaceassemblymagneticcorememorieslinearattenuationanddelaycharacteristics磁心存储器线性衰减和时延特性传输损伤transmissionimpairments语音中的冗余特性在数据发送器中的编码过程二进制的不归零信号4.互联网theredundantnatureofspeechcodingprocessinthedatatransmitterbinarynonreturn-to-zerosignal网络资源：信息服务：远程终端：互联的系统：networkresourceinformationservicesremoteterminalsinterconnectedsystems命令：command电子邮件：electronicmail主机：host无线信道：搜索工具：用户界面：wirelesschannelssearchingtoolsuserinterface存取：access文本信息：textualmessages协议：protocol超文本协议：hypertextprotocol分布在全世界的计算机的巨大网络：gaintnetworkofcomputerslocatedallovertheworld主干系统：backbonesystem全国范围的网络：电子会议：nationwildnetworkelectronicconferencesliveconversation实时对话：

最大的信息库thelargestrepositoryofthecomputersonthenetnetworkfacilitiesresources网络设备资源：在网上的绝大多数计算机：UNIX操作系统：在因特网和你的thevastmajorityofthecomputeronthenettheUNIXoperatingsystemPC机之间传送数据的方法：awaytomovedatabetweentheinternetandyourPC方便的搜索工具：联网的超文本协议：5.光纤通信介绍theconvenientsearchingtoolsthenetworkhypertextprotocol光纤通信光源：:opticalfibercommunicationslightsource波长：wavelength激光器：色散：laserdispersion传输介质：多模光纤：长途干线：单模光纤：transmissionmediummulti-modefiberlong-houltrunkssinger-modefiber带宽：bandwidth带宽用户：widebandsubscriber纤维光学：fiber-optics商用技术：commercialtechnologethreshodcurrent门限电流：光检测器：photodetector波分复用：wavelengthmultiplexingfiber-opticnetworkvideobandwidth纤维光网络：视频带宽：长途传输：longdistancetransmissionrepeaterspacing中继距离：已装光纤的总长度：长途通信系统：低衰减的石英纤维：衰减接近瑞利极限的光纤：室温下的门限电流：较长波长区：thetotallengthofinstalledfiberlong-haultelecommunicationsystemthelow-losssilicafiberfiberswithlossesapproachingtheRayleighlimitroomtemperaturethresholdcurrentsthelongerwavelengthregion用户接入工程：部件性能和可靠性的改进：已安装的光纤系统的数据速率：subscriberaccessprojectimprovementsincomponentperformanceandreliabilitydataratesforinstalledfibreopticsystem每秒吉比特：波分复用：gigabitpersecondrangewavelengthmultiplexing带宽用户环路系统：多纤连接器：设计寿命：widebendsubscriberloopsystemmultifibreconnectorsprojectedlifetime光源：lightsource单模光纤：single-modefibre

分布反馈式激光器：信息容量：distributed-feedbacklaserinformationcapacity交换体系：switchinghierarchybroadbandservices带宽业务：6.同步数字系列同步数字系统：国际标准：synchronousdigitalhierarchyinternationalstandardsignalformat信号格式：网络节点接口：支路信号：networknodeinterfacetributarysignals数字交叉连接：网络管理：digitalcross-connectionnetworkmanagement网络维护：networkmaintenancenetworkoperators网络运营者：传输速率：transmissionrate支路映射：tributarymapping灵活性：flexibility用户业务：subscriberservices覆盖层：overlaylevels制造商：manufacturer同步传输帧：线路终端复用器：分插复用器：再生中继器：synchronoustransmissionframelineterminalmultiplexeradd-dropmultiplexerregenerator灵敏度：sensitivity虚容器：virtualcontainer成帧字节：段开销：framingbytessectionoverhead端到端传输：误码监视：信号处理节点：end-to-endtransmissionerrormonitoringsignalprocessingnodes净负荷：payload指针：pointer同步传输系统：synchronoustransmissionsystem覆盖nni的标准：国际标准接口：thestandardcoveringtheNNItheinternationalstandardinterfacedirectsynchronousmultiplexing直接同步复用：灵活的通信联网：flexibletelecommunicationnetworkingpoint-to-pointtransmissiontechnologyadvancednetworkmanagement点对点的传输技术：先进的网络管理：不同厂家提供的设备：SDH提供的灵活性：同步复用设备的运营者：theequipmentsuppliedbydifferentmanmufacturerstheflexibilityprovidedbySDHoperatorofsynchronousmultiplexers电信联网：telecommunicationnetworking

支路信号：维护能力：tributarysignalsmaintenancecapabilities统一的电信网络基础结构：unifiedtelecommunicationnetworkinfrastructure组件：buildingblocks终端复用器：贯通方式：terminalmultiplexerthrough-modefashionsynchronousDXC同步数字交叉链接：可变带宽：aryingbandwidth各个支路信号：传输系统：individualtributarysignalstransportsystem光载体：opticalcarrier二维图形：2-dimensionalmap传输次序：theorderoftransmission7.波分复用对光特性的理解：基本重要性：theunderstandingofthepropertyoflightthefundamentalimportant想象今天的通信系统：光的高速公路：巨量的信息：toimaginethecommunicationsystemoftodaythehighwayoflightthemassiveamountofinformationtoadoptnewcommunicationtechnologythelargeamountsofvideoinformationthewavedividemultiplexing采用通信新技术：大量的视频信息：波分复用：只发送单个波长：传输大量的波长：无差错传输：tosendonlyonewavelengthtotransmitalargeamountofwavelengththeerror-freetransmission自愈特性：theself-healingpropertys直接接入光网络：视频信息：toaccessdirectlytotheoptialnetworkthevideoinformation导致WDM革命的主要进展：光放大器的发明：themajoradvancethatledtotherevolutiontheinventionoftheopticalamplifier下一段光纤：thenextspanoffiber提高所有波长信号的功率：在光放大器方面的进展：增益均衡技术的发展：多波长传输：toboostthesignalpowerofallwavelengththeadvancesinopticalamplifierthedevelopmentofgainequalizationtechniquesthemultiple-wavelengthtransmissionthegrowthofvariousapplicationthewidevariousapplication无线系统的增长：各种各样的业务：处理各种业务类型：全光交叉连接：tohandlevarioustypesoftraffictheall-opticalcross-connect8.寻呼系统的发展通信手段：被叫人：communicationmeanscalledperson紧急通信：移动电话网：urgentcommunicationsmobiletelephonenetwork

电话交换台：寻呼业务：电子电路：无线传输：无线发射机：个人代码：telephoneswitchboardpagingserviceelectroniccircuitrywirelesstransmissionwirelesstransmitterpersonalcodes服务区：servicearea单向通信：寻呼用户：顾客：one-waycommunicationpaginguserscustomer技术进步：系统的效率：专用的无线网络：终端设备：全球覆盖：无线增益：空间站：technologicalprogressefficiencyofthesystemdedicatedwirelessnetworkterminalequipmentglobalcoveragegainoftheantennaspacestation通信网络的运行：theoperationofacommunicationnetwork有线的和移动的电话网络：光和声音的信号装置：本地电话交换台的接线员：第一代寻呼系统：thewiredandmobiletelephonenetworkopticalandacousticalsignalingdevicestheoperatorofalocaltelephoneswitchboardthefirstgenerationofpagingsystemthepagingsystemusingwirelesstransmissionthededicatedradioreceiver利用无线传输的寻呼系统：专用的无线接收机：社会和经济效益：socialandeconomicadvantages电子电路的小型化：价格效率比：theminiaturizationofelectroniccircuitrycostefficiency小型无线电接收机：theminiatureradioreceiver显示能力：displaycapability全球覆盖：globalcoverage空间站的天线增益：地球同步轨道卫星：用户终端：thespacestationantennagaingeostationaryorbitsatelliteuserterminal9.蜂窝式移动电话系统蜂窝式移动电话：cellularmobiletelephone服务性能：servicesperformance频谱：frequencyspectrum频带：frequencyband微处理器：广播业务：microprocessor移动手机：mobileunitbroadcastservise天线：antenna子系统：subsystems移动用户：mobilesubscriber服务能力：利用率：servicecapabilityutilization带宽：bandwidth单边带：single-sideband扩频：spreadspectrumlargescaleintegratedcircuits大规模集成电路：

蜂窝点：cellularsite蜂窝交换机：radiocabinet呼叫处理：cellularswitchcallprocessing无线机架：频谱利用率：frequencyspectrumutilizationthelimitedassigendferquencyband服务区：serviseareacomplicatedfeaturesandfunctionslarge-scaleintegraesdcircuittechnologydevelopmentalcellularsystem有限的指定频带：复杂的特性和功能：大规模集成电路技术：试验性的蜂窝系统：中央协调单元：蜂窝管理：centralcoordinatingelementcellularadministration传统移动电话的运行限制：有限的服务能力：无线通信行业：operationallimitiationofconventionalmobiletelephonesystemlimitiedservicecapabilityradiocommuncationindustryavailableradiofrequencyspectrumtheallocatedfrequencybandmobiletransceiver可用的无线电频谱：所分配的频带：移动收发信机：技术上的可行性：严格的频谱限制：调频广播业务：techologicalfeasibilityseverespectrumlimitationsFMbroadcastingservicespropagrationpathloss传播路径衰耗：多径衰耗：multipathfading电话公司地方局:telephonecompanyzoneoffices10.全球移动通信系统个人通信personalcommuncation通信标准communcationstandradsfixedtelephoneservicesnetworkcapability固定电话业务网络容量移动交换中心国际漫游mobileswitchingcenterinternationalroamingbroadbandservices宽带业务接口转换interfaceconversionfrequencyallocationanaloguemode频谱分配模拟方式蜂窝通信原理cellularcommuncationprincipe拥塞jamming蜂窝裂变cellularsplitting基站basestation寄存器register收费功能接入方法billingfunctionaccessmethod突发脉冲传输方式开销信息brustytransimissionmodeoverheadinformation切换算法handoveralgorithms短消息服务技术规范shortmessageservicestechnicalspecification

totalaccesscommuncationsystem全接入的通信系统globalmobilecommuncationsystem全球移动通信系统timedivisionmultipleaccess时分多址facsimileandshortmessageservices传真和短消息服务fixedcommuncationnetworks固定通信网络amorepersonalizedsystem更加个性化的系统thecostandqualityofthelink链路的价格和质量marketgrowth市场的发展fixedtelephoneservice固定电话服务coxialcable同轴电缆interfaceconvision接口转换cellularcommuncationpriciple蜂窝通信原则frequencyreuseandcellsplitting频率复用和蜂窝裂变cochannelinterference共信道干扰theoreticalspectualcapability理论上的频谱容量micro-cellularsystem微蜂窝系统basestationtransceiver基站收发信机subscriberregister用户寄存器bursttransmissionmode突发脉冲传输模式overheadinformation开销信息advancedhandoveralgorithms先进的切换算法facsimileandshortmessageservices传真和短消息服务theGSMtechniquespecicationsGSM技术规范说明11.电路交换和分组交换电路交换分组交换报文交换子网circuitswitchingpacketswitchingmessageswitchingsubnet信头header目的地址误差控制存储转发方式destinationaddresserrorcontrolstore-and-forwardmanner突发性bursty传输时延transimissiondelay中间交换设备交换技术intermediateswitchingequipmentswitchingtechniquereturnsignal返回信号报文处理机给定最大长度信息转移messageprocessorgivenmaximumlengthinformationtransfer随机性random专用电路dedicatedcircuit电路利用率channelultilizationthecapabilityofsoringormanipulatinguser'sdata存储和处理用户数据的能力thespecialsignalingmessage特定的信令信息awelldefinedblockdfdatacalldeamessage被精心定义的称为报文的数据块theinformationregardingthesourceanddestinationaddress涉及源和目的地址的信息

thecomputerreferredtoamessageprocessor叫做报文处理器的计算机thestore-and-forwardtransmissiontechnique存储转发传输技术thedynamicallocationofbandwith带宽的动态分配theoveralltransmissiondelayofmessage报文整个的传输时延switchingtechnique交换技术ciruitswitching电路交换messageswitching报文交换packetswitching分组交换totalpathofconnectedlines连线的整个通路source-destinationpair源到目的地的一对communicationparties通信各方transmissionunit传输单元intialconnectioncostincurredinsettingupthecircuit在建立电路时的起初连接成本lowdelayconstraintrequiredbytheuser用户所需的最短时延的限制thefixeddedicatededend-to-endcircuit固定专用的端到端电路lowchannelultization低的电路利用率12.ATM异步转移模式异步转移模式逻辑信道虚电路asynchronouslogicalchannelvirtualcircuitsvirtualpaths虚路径建议recommendationnetworklevel网络层业务与应用层虚连接serviceandapplicationvirtualconnection信息高速公路点播电视informationsuperhighwayvideo-on-demand统计复用statisticalmultiplexingdigitalinformationidentifer数字化的信息标识符协议protocols网络节点宽带网networknodebroadbandnetworkATM论坛ATMforum面向未来图象编码虚拟专用网数据处理future-proofedimageencodeingvirtualprivatenetworkdataprocessing被叫做信元的短的分组每秒几百兆比特的速率独特的复用方法shortpacketscalledcellsbitratesofseveralhundredmegabitsaseconduniquemultiplexingmethod任何两个终端之间的物理连接交互式的视频业务thephysicalconnectionbetweenanytwoterminalsinteractivevideoservices多媒体业务的自然载体anaturevehicleformultimediaservices

运营者和用户当前和未来的要求高比特率信道的交换技术thecurrentandfuturerequirementofbothperatorsandusersthetechniqueforswitchinghighbitratechannel异步转换模式复用和交换技术所承载的传输类型双重标识asychornoustransfermodemultiplexingandswitchingtechniquetheunderlyingtypeoftransmissiondualidentification虚电路virtualcircuitvirtualpath虚路径信元在网络节点上的转移每秒几百爪比特thetransferofcellstothenetworknodeshundredsmegabitsasecondI.121建议recommendationI.121服务质量thequalityofservice与实际需求成比例inproportiontotheexactrequirement网络所传送的应用和业务构成虚网络的能力theapplicationsandservicetransportedoveranetworktheabilitytoconstructvirtualnetworks低价高效的利用网络设施cost-effectiveuseofinfrastructure面向未来的future-proofed协调传送不同业务的不同网络未来的信息高速公路的基本部件coordinatingdifferentnetworkscarryingdifferentservicesessentialcomponentsoffutureinformationsuperhighways统计复用statisticalmultiplexing资源的最佳使用虚拟专用网13.多媒体多媒体optimumuseofresourcesvirtualprivatenetworksmultimedia交互环境interactiveenviornmentvideocompressin视频压缩高清晰度电视数字信号处理器点播业务highdefinitiontelevisiondigitalsignalprocessoron-demandservices视频服务器硬件、软件和应用videoservershardware,softwareandapplicationsstorage彩显colourmoniter全活动图象视频编码器字节fullmotionpicturevisionencoderbytemixtureofhardware,softwareandapplications硬件、软件和应用层interactiveenvironment交互环境personaldesktopcomputers个人桌面电脑videocompression视频压缩thevisionencoder视频编码器video-on-demandinteractiveservices交互式视频点播业务multimediaenviroment多媒体环境visualimages视频图象

harddiskstorage硬盘存储colourmonitor彩显thestandardsofmultimedia多媒体标准motionpictures活动图象consumerqualityofvideoandaudio顾客质量的视频和音频broadcastimages广播图象highdefinitiontelevision高清晰度电视codingalgorithms编码算法digitalsignalsprocessor数字信号处理器14.公用电信网公用电信网本地环路publictelecommunicationnetworklocalloop交换节点switchingnode双绞线twistedpair外部呼叫externalcall端局endoffice数字数据系统二线连接digitaldatasystemstwowireconnection收费中心tollcenter电路交换网电话用户circuit-switchingnetworktelephonesubscriberdatatrafficlink数据流量链路中继线trunk半双工的half-duplex全双工的full-duplex中间交换节点音频电路intermediateswitchingnodevoice-frequencycircuittandemswitch汇接交换机拓扑topology接点间的internode路由route全双工的连接集中话务量的功能被称为汇接交换机的交换节点一小部分用户在站和网络之间的接口发送数字信号的用户full-duplexconnectionthefuncionofconcentratingtraffictheswitchingnodecalledtandemswitchafractionofsubscriberstheinterfacebetweenthestationandthenetworkthesubscriberthattransmitdigitalsignal国家网络nationalnetwork结构部件architecturalcomponents接点间的支路树状拓扑thebranchesbetweennodestreetopology传输设备transmissionfacilitiesmultiplevoice-frequencycircuits多条音频电路

同步时分复用synchronousTDM相邻的端局adjacentendofficesfullconnectivity全连通性被分离开的子网高效中继线isolatedsubnetworkshigh-usagetrunks路由选择的基本次序主干体系网络basicorderofselectionbackbonehierarchicalnetwork连到不同端局的俩个用户different交换区twosubscribersattachedtoofficeexchangearea15.综合业务数字网全球通信globalcommunications灵活性flexibility端到端的数字连接开放网络end-to-enddigitalconnectivityopennetwork语声编码voiceencoding综合业务数字网系统结构integratedservicesdigitalnetworkinfrastructure国际标准化组织通信载体InternationalOrganizationforStandardizationcommunicationcarriers传输媒体transmissionmedium接口设备interfaceequipment带宽限制bandwidthlimitation交换设备switchingequipment语音编码voiceencoding脉码调制pulsecodemodulation基本接入basicaccess综合业务数字网国际标准化组织theintegratedservicesdigitalnetworktheInternationalOrganizationforStandardization由于传输媒体导致的质量下降4kHz话路中所固有的带宽限制标准化的接口degradationduetothetransmissionmediumbandwidthlimitationsinherentina4kHzvoicechannelstandardizedports脉（冲编）码调制pulsecodemodulation数字通信digitalcommunicationISDN的标准和系统结构全球通信ISDNstandardsandsystemarchitectureglobalcommunication数字技术的逐步应用共同通信载体progressiveapplicationofdigitaltechnologypubliccommunicationcarriers高质量enhancedquality大量的接口设备在传送话音、substantialquantityofinterfaceequipment数据、视频和其他业务上的灵活性flexibilityinthetransmissionofvoice,data,videoandotherservices带宽的限制bandwidthlimitations端到端的数字连接end-to-enddigitalconnectivity

语音编码技术基本接入信令速率统一的接入试验性的技术16.电信世界的业务和未来X.25协议电视信号voiceencodingtechniquesbasicaccesssignalingrateuniversalaccessexperimentaltechnologyX.25protocoltelevisionsignalsnarrowbandservicesbasicaccess宽带业务基本接入电信业务teleservice用户电报telex无线电波radiowaves地面天线groundantenna同轴的coaxial直接广播系统端到端