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:samplingfrequency抽样速率:samplingrate脉冲流:streamofpulses重复率:repetitionrate编码过程:codingprocess模拟信号:analogsignal传输质量:transmissionquality数字通信:digitalcommunication数字传输:digitaltransmission含噪声的环境:noisyenvironment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:8-digitsequence接受端:receivingterminal帧格式:frameformat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:asequenceof8-binarydigits理论上的最小抽样频率:aminimumtheoreticalsamplingfrequency占据着300Hz到3.4kHz频率范围的话路:avoicechanneloccupyingtherange300Hzto3.4kHz每个样值8-位码:8-digitspersamplevalue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:relationshipofthetruesignaltothenoisesignal由卫星上接受到的信号:thesignalreceivedfromasatellite一条特定消息中的全部信息:thecompleteinformatianaboutaparticularmessage被传信号的波形: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:theunitthatconvertssampledamplitudevaluetoasetofpulses涉及到第一路，第二路及其他各路的序列:asequencerelatingtochannel1,2andsoon被称为同步字的独特码序列:auniquesequenceofpulsescalledsynchronizationword地面系统:terrestrialsystem脉冲的“有”或“无”:thepresenceorabsenceofthepulses高速的电子开关:ahigh-speedelectronicswitch时分多路复用器:thetimedivisionmultiplexer时分多路复用:TimeDivisionMultiplexer2.异步串行数据传输串行接口serialinterface显示终端CRTterminal发送器与接收器transmitterandreceiver数据传输datatransmission数据流datastream闲置状态theidlestate传号电平marklevel空号电位spacelevel起始位startbit停止位stopbitT秒的持续时间durationofTseconds奇偶校检位paritybit错误标志errorflag传输错误transmissionerror下降沿fallinfedge符号间的空格intersymbolspace接收机的定时receivertiming本地时钟localclock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asynchronousserialdatatransmission最为流行的串行接口themostpopularserialinterface所传送的数据thetransmitteddata发送器与接收器的时钟theclocksatthetransmitterandreceiver电传机的时代theeraofteleprinter一个字符的点和划thedotsanddashsofacharacter符号间空格持续时间的三倍threetimesthedurationofintersymbolspace被称为字符的比特组thegroupofbitscalledcharacters由7或8个比特的信息组成的固定单元theinvariableunitscomprising7or8bitsofinformation由接收机本地产生的时钟aclockgeneratedlocallybythereceiver在字符后所收到的奇偶校检位thereceivedparitybitfollowingthecharacter起始位的下降沿thefallingedgeofthestartbit数据链路面向字符的特性thecharacter-orientednatureofthedatalink3.数据通信地下电缆undergroundcable通信卫星communicationsatellite微波设备microwavefacilities调制器与解调器modulatoranddemodulator缓冲器buffer定时信号timingsignals同步脉冲synchronizationpulses时隙timeslot移位寄存器shiftregister传输媒体transmissionmedium线形衰弱linearattenuation信息安全informationsecurity键盘keyboard数据终端dataterminals某种类型的数据转换设备sometypeofdataconversionequipment视频显示终端visualdisplayterminal称为数据调制解调器的双向数据发送接收机two-waydatatransmistter-receivercalledadatamodem全双工的数据传输系统full-duplexdatatrandmissionsystem由数据处理器的运算速率所决定的速率theratedeterminedbytheoperatingspeedofthedataprocessor由接口部件来的定时信号timingsignalsfromtheinterfaceassembly磁心存储器magneticcorememories线性衰减和时延特性linearattenuationanddelaycharacteristics传输损伤transmissionimpairments语音中的冗余特性theredundantnatureofspeech在数据发送器中的编码过程codingprocessinthedatatransmitter二进制的不归零信号binarynonreturn-to-zerosignal4.互联网网络资源：networkresource信息服务：informationservices远程终端：remoteterminals互联的系统：interconnectedsystems命令：command电子邮件：electronicmail主机：host无线信道：wirelesschannels搜索工具：searchingtools用户界面：userinterface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：nationwildnetwork电子会议：electronicconferences实时对话：liveconversation最大的信息库thelargestrepositoryofthecomputersonthenet网络设备资源：networkfacilitiesresources在网上的绝大多数计算机：thevastmajorityofthecomputeronthenetUNIX操作系统：theUNIXoperatingsystem在因特网和你的PC机之间传送数据的方法：awaytomovedatabetweentheinternetandyourPC方便的搜索工具：theconvenientsearchingtools联网的超文本协议：thenetworkhypertextprotocol5.光纤通信介绍光纤通信:opticalfibercommunications光源：lightsource波长：wavelength激光器：laser色散：dispersion传输介质：transmissionmedium多模光纤：multi-modefiber长途干线：long-houltrunks单模光纤：singer-modefiber带宽：bandwidth带宽用户：widebandsubscriber纤维光学：fiber-optics商用技术：commercialtechnologe门限电流：threshodcurrent光检测器：photodetector波分复用：wavelengthmultiplexing纤维光网络：fiber-opticnetwork视频带宽：videobandwidth长途传输：longdistancetransmission中继距离：repeaterspacing已装光纤的总长度：thetotallengthofinstalledfiber长途通信系统：long-haultelecommunicationsystem低衰减的石英纤维：thelow-losssilicafiber衰减接近瑞利极限的光纤：fiberswithlossesapproachingtheRayleighlimit室温下的门限电流：roomtemperaturethresholdcurrents较长波长区：thelongerwavelengthregion用户接入工程：subscriberaccessproject部件性能和可靠性的改进：improvementsincomponentperformanceandreliability已安装的光纤系统的数据速率：dataratesforinstalledfibreopticsystem每秒吉比特：gigabitpersecondrange波分复用：wavelengthmultiplexing带宽用户环路系统：widebendsubscriberloopsystem多纤连接器：multifibreconnectors设计寿命：projectedlifetime光源：lightsource单模光纤：single-modefibre分布反馈式激光器：distributed-feedbacklaser信息容量：informationcapacity交换体系：switchinghierarchy带宽业务：broadband