2023年高级通信工程师考试复习题

通信英语强化训练试题（一）Ⅰ单项选择题：(Choosethebestone)

A.convey,occupy B.toconvey,occupying

C.conveying,occupied D.convey,tooccupyForexample,thesignal_________fromasatellite,_________infarouterspace,isveryweak.

A.received,located B.receive,locate

C.receiving,locating D.toreceive,tolocateA.obtain,detect B.beobtained,detecting

C.obtained,detected D.obtaining,detected4.Thereisaninherentadvantagefor_________noisyenvironmentsby_________digitaltransmission.

A.overcoming,choose B.overcome,choosing

C.overcome,choose D.overcoming,choosingEachvoicechannelhasaseparatecoder，theunit_________convertssampledamplitudevaluestoasetofpulses;Anddecoder,theunit_________performsthereverseoperation.

A.who,who B.when,when

C.where,where D.that,thatTheproblemiseasilyovercomeby_________aframeformat,whereatthestartofeachframeauniquesequenceofpulsesisplaced_________thestartoftheframe.

A.specify,identify B.specifying,soastoidentify

C.specified,identified D.specify,identifyingAnasynchronousserialdatalinkissaid_________characteroriented，asinformationistransmittedintheformofgroupsofbits_________characters.

A.be，calling B.tobeing，tocall

C.been，call D.tobe，calledThisinterfaceissocalledbecausethe_________dataandthe_________dataarenotsynchronizedoveranyextendedperiod.

A.transmit，receive B.totransmit，toreceive

C.transmitting，receiving D.transmitted，receivedSerialdatatransmissionsystems_________inthetelephone，Morsecode,andeventhesmokesignalsonce_________bynativeAmericans.

A.arefinding，using B.arefound，used

C.find,use D.befound,usingTraditionally，theidlestate_________themarklevel.Byconventionthiscorresponds_________alogical1level.

A.isreferredto,as B.isreferredas,in

C,isreferredtoas,to D.isreferred，withinThetransmitterthensendsthecharacter，1bitatatime，by_________eachsuccessivebitonthelineforadurationofTseconds,_________allbitshavebeentransmitted.

A.place,still B.placed，since

C.placing,until D.placing，becauseWhenthedatalinkconnectsaCRTterminal_________acomputer，_________problemsarise,astheterminalisitselfcharacteroriented.

A.into,many B.on，afew

C.in,afew D.to，few_________thereceivingendofasynchronousserialdatalink，thereceivercontinuallymonitorstheline_________astartbit.

A.On，looking B.Within，lookfor

C.In,lookat D.At，lookingforAscompaniesrealizedtheycouldsavemoneyandgainproductivityby_________networkingtechnology,theyaddednetworksandexpanded_________networksalmostasrapidlyasnewnetworktechnologiesandproductscouldbeintroduced.

A.use,exist B.using,existing

C.touse,toexist D.used,existedTheOSIreferencemodelallowsyou_________thenetworkfunctionsthatoccurateachlayer.Moreimportantly,theOSIreferencemodelisaframeworkyoucanuse_________howinformationtravelsthroughoutanetwork.

A.view,understand B.viewing,understanding

C.viewed,understood D.toview,tounderstandThetransportlayersegmentsdatafromthe_________host’ssystemandreassemblesthedataintoadatastreamonthe_________host’ssystem.

A.sending,receiving B.tosend,toreceive

C.sent,received D.send,receiveThedatalinklayerprovidesthetransitofdata_________aphysicallink.Insodoing,thedatalinklayerisconcerned_________physicaladdressing,networktopology,networkmediaaccess,anderrordetection.

A.with,across B.at,in

C.between,in D.across,with

Ⅱ短语英译汉：(TranslatethefollowingphrasesintoChinese)

theschemesforperformingthesethreefunctions

aseriesofamplitudevalues

aspeechchanneloftelephonequality

asequenceof8-binarydigits

aminimumtheoreticalsamplingfrequency

avoicechanneloccupyingtherange300Hzto3.4kHz

8-digitspersamplevalue

thesparkingofacarignitionsystem

thestreamofthepulseswitharepetitionrateof64kHz

therelationshipofthetruesignaltothenoisesignal

thesignalreceivedfromasatellite

thecompleteinformationaboutaparticularmessage

theshapeofthetransmittedsignal

theattenuationintroducedbytransmissionpath

theunitthatconvertssampledamplitudevaluetoasetofpulses

asequencerelatingtochannel1,2andsoon

auniquesequenceofpulsescalledsynchronizationword

terrestrialsystem

thepresenceorabsenceofthepulse

ahigh-speedelectronicswitch

thetimedivisionmultiplexer

TimeDivisionMultiplexing

asynchronousserialdatatransmission

themostpopularserialinterface

thetransmitteddata

theclocksatthetransmitterandreceiver

theeraofteleprinter

thedotsanddashesofacharacter

threetimesthedurationofintersymbolspace

thegroupofbitscalledcharacters

theinvariableunitscomprising7or8bitsofinformation

aclockgeneratedlocallybythereceiver

thereceivedparitybitfollowingthecharacter

thefallingedgeofthestartbit

thecharacter-orientednatureofthedatalink

networkingtechnology

proprietarynetworkingsystem

theInternationalOrganizationforStandardization

compatibilitybetweenthevarioustypesofnetworks

sevennumberedlayers

standardizationofnetworkcomponents

errorrecovery

receivinghost'ssystem

connection-orientedcircuits

informationflowcontrol

networktopology

networkmediaaccess

electricalspecification

maximumtransmissiondistance

Ⅲ短语汉译英：(TranslatethefollowingphrasesintoEnglish)

抽样量化与编码话路幅值抽样频率抽样速率脉冲流反复率编码过程模拟信号传播质量数字通信数字传播含噪声旳环境传播路由信噪比信号电平地面系统噪声功率二进制传播反向操作8位码序列接受端帧格式同步字串行接口显示终端发送器与接受器数据传播数据流闲置状态传号电平空号电平起始位停止位T秒旳持续时间奇偶校验位错误标志传播错误下降沿符号间旳空格接受机旳定期当地时钟磁带控制比特逻辑1电平二进制数据明显旳缺陷联网技术国际原则化组织参照模型数据分组应用程序网络媒体分层硬件和软件表达层传播层数据链路层网络服务文献接入数据格式主机协议连接逻辑选址

Ⅳ请将下述短文译成中文（短文英译汉）：(TranslatethefollowingpassagesintoChinese)

Ifweconsiderbinarytransmission,thecompleteinformationaboutaparticularmessagewillalwaysbeobtainedbysimplydetectingthepresenceorabsenceofthepulse.Bycomparison,mostotherformsoftransmissionsystemconveythemessageinformationusingtheshape,orlevelofthetransmittedsignal;parametersthataremosteasilyaffectedbythenoiseandattenuationintroducedbythetransmissionpath.Consequentlythereisaninherentadvantageforovercomingnoisyenvironmentsbychoosingdigitaltransmission.

Thereadermayask,howdoesthedemultiplexerknowwhichgroupof8-digitsrelatestochannel1,2,andsoon?Clearlythisisimportant!Theproblemiseasilyovercomebyspecifyingaframeformat,whereatthestartofeachframeauniquesequenceofpulsescalledtheframecode,orsynchronizationword,isplacedsoastoidentifythestartoftheframe.Acircuitofthedemultiplexerisarrangedtodetectthesynchronizationword,andtherebyitknowsthatthenextgroupof8-digitscorrespondstochannel1.

Basically,ifthesignalisverylargecomparedtothenoiselevel,thenaperfectmessagecantakeplace;however,thisisnotalwaysthecase.Forexample,thesignalreceivedfromasatellite,locatedinfarouterspace,isveryweakandisatalevelonlyslightlyabovethatofthenoise.Alternativeexamplesmaybe.Foundwithinterrestrialsystemswhere,althoughthemessagesignalisstrong,soisthenoisepower.

Sofarwehaveassumedthateachvoicechannelhasaseparatecoder,theunitthatconvertssampledamplitudevaluestoasetofpulses;anddecoder,theunitthatperformsthereverseoperation.Thisneednotbeso,andsystemsareinoperationwhereasinglecodesissharedbetween24,30,oreven120separatechannels.

Ahigh-speedelectronicswitchisusedtopresenttheanaloginformationsignalofeachchannel,takeninturn,tothecodec.Thecodecisthenarrangedtosequentiallysampletheamplitudevalue,andcodethisvalueintothe8-digitsequence.Thustheoutputtothecodecmaybeseenasasequenceof8pulsesrelatingtochannel1,thenchannel2,andsoon.Thisunitiscalledatimedivisionmultiplexer.

Anasynchronousserialdatalinkissaidtobecharacter-oriented,asinformationistransmittedintheformofgroupscalledcharacters.Thesecharactersareinvariableunitscomprising7or8bitsofinformationplus2to4controlbitsandfrequentlycorrespondtoASCII-encodedcharacters.Initially,whennoinformationisbeingtransmitted,thelineisinanidlestate.Theidlestateisreferredtoasthemarklevelandcorrespondstoalogical1level.

Whenthetransmitterwishestosenddata,itfirstplacesthelineinaspacelevelforoneelementperiod.Thetransmitterthensendsthecharacter,1bitatatime,byplacingeachsuccessivebitonthelineforadurationofTseconds,untilallbitshavebeentransmitted.Thenasingleparitybitiscalculatedbythetransmitterandsentafterthedatabits.Finally,thetransmittersendsastopbitatamarklevelforoneortwobitperiod.

Themostobviousdisadvantageofasynchronousdatatransmissionistheneedforastart,parity,andstopbitforeachtransmittedcharacter.If7bitcharactersareused,theoverallefficiencyisonly70percent.Alessobviousdisadvantageisduetothecharacter-orientednatureofthedatalink.WheneverthedatalinkconnectsaCRTterminaltoacomputer,fewproblemsarise,astheterminalisitselfcharacteroriented.

Themostcriticalaspectofthesystemisthereceivertiming.Thefallingedgeofthestartbittriggersthereceiver'slocalclock,whichsampleseachincomingbitatitsnominalcenter.SupposethereceiverclockwaitsT/2secondsfromthefallingedgeofastartbitandsamplestheincomingdataeveryTsecondsthereafteruntilthestopbithasbeensampled.Asthereceiver'sclockisnotsynchronizedwiththetransmitterclock,thesamplingisnotexact.

MostcomputerterminalstransmitandreceiveASCIIcharacters,andweknowthattheASCIIcharactersrequire7bits.Therefore,7bitsofdataplusaparitybitaresenteachtimeacharacteristransmittedorreceivedbytheterminal.Thetwomostobviouswaystosendthecharactersarebyparalleltransmissionorbyserialtransmission.MostterminalshavebeendesignedtotransmitandreceiveASCIIcharactersasserialdata.

TheearlydevelopmentofLANs,MANs,andWANswaschaoticinmanyways.Theearly1980ssawtremendousincreasesinthenumbersandsizesofnetworks.Ascompaniesrealizedtheycouldsavemoneyandgainproductivitybyusingnetworkingtechnology,theyaddednetworksandexpandedexistingnetworksalmostasrapidlyasnewnetworktechnologiesandproductscouldbeintroduced.

Proprietarysystemsareprivatelydeveloped,owned,andcontrolled.Inthecomputerindustry,proprietaryistheoppositeofopen.Proprietarymeansthatoneorasmallgroupofcompaniescontrolsallusageandevolutionofthetechnology.Openmeansthatfreeusageofthetechnologyisavailabletothepublic.

TheOSIreferencemodelallowsyoutoviewthenetworkfunctionsthatoccurateachlayer.Moreimportantly,theOSIreferencemodelisaframeworkyoucanusetounderstandhowinformationtravelsthroughoutanetwork.Inaddition,theOSIreferencemodelcanbeusedtovisualizehowinformation,ordatapackets,travelsfromapplicationprograms,throughanetworkmedium,tootherapplicationprogramsthatarelocatedinanothercomputeronanetwork,evenifthesenderandthereceiverhavedifferenttypesofnetworkmedia.

TheapplicationlayeristheOSIlayerthatisclosesttotheuser.Itprovidesnetworkservices,suchasfileaccessandprinting,totheuser’sapplications.ItdiffersfromtheotherlayersinthatitdoesnotprovideservicestoanyotherOSIlayer,butrather,onlytoapplicationsoutsidetheOSImodel.Theapplicationlayerestablishestheavailabilityofintendedcommunicationpartners.Italsosynchronizesandestablishesanagreementonproceduresforerrorrecoveryandcontrolofdataintegrity.

Thetransportlayerattemptstoprovideadatatransportservicethatshieldstheupperlayersfromtransportimplementationdetails.Specifically,suchissueashowreliabletransportbetweentwohostsisaccomplishedintheconcernofthetransportlayer.Inprovidingcommunicationservice,thetransportlayerestablishes,maintains,andproperlyterminatesconnection-orientedcircuits.Inprovidingreliableservice,transporterror

detection-and-recoveryandinformationflowcontrolareused.

Thephysicallayerdefinestheelectrical,mechanical,procedural,andfunctionalspecificationsforactivating,maintaining,anddeactivatingthephysicallinkbetweenendsystems.Suchcharacteristicsasvoltagelevels,timingofvoltagechanges,physicaldatarates,maximumtransmissiondistances,physicalconnectors,andother,similar,attributesaredefinedbyphysicallayerspecifications.Ⅴ阅读理解：(Trueorfalsestatement)Accordingtothefollowingtext'sdecidewhetherthestatementsfollowingthetextsaretrue(T)orfalse(F)

PASSAGEONEDigitaltransmissionprovidesapowerfulmethodforovercomingnoisyenvironments.Noisecanbeintroducedintotransmissionpathinmanydifferentways:perhapsviaanearbylightningstrike,thesparkingofacarignitionsystem,orthethermallow-levelnoisewithinthecommunicationequipmentitself.Itistherelationshipofthetruesignaltothenoisesignal,knownasthesignal-to-noiseratio,whichisofthemostinteresttothecommunicationengineer.Basically,ifthesignalisverylargecomparedtothenoiselevel,thenaperfectmessagecantakeplace;however,thisisnotalwaysthecase.Forexample,thesignalreceivedfromasatellite,locatedinfarouterspace,isveryweakandisatalevelonlyslightlyabovethatofthenoise.Alternativeexamplesmaybefoundwithinterrestrialsystemswhere,althoughthemessagesignalisstrong,soisthenoisepower.Ifweconsiderbinarytransmission,thecompleteinformationaboutaparticularmessagewillalwaysbeobtainedbysimplydetectingthepresenceorabsenceofthepulse.Bycomparison,mostotherformsoftransmissionsystemsconveythemessageinformationusingtheshape,orlevelofthetransmittedsignal;parametersthataremosteasilyaffectedbythenoiseandattenuationintroducedbythetransmissionpath.Consequentlythereisaninherentadvantageforovercomingnoisyenvironmentsbychoosingdigitaltransmission.

Ifthetruesignalisverylargecomparedtothenoiselevel,thentheinformationwithhigherqualitycanbeobtained.Ifweconsiderbinarytransmission,thecompleteinformationaboutaparticularmessagewillalwaysbeobtainedbydetectingtheshapeofthetransmittedsignalorbycalculatingtheparametersofthetransmittedsignal.Itisthesignal-to-noiseratiowhichisofthemostinteresttothecommunicationengineer.Digitaltransmissionprovidesthesignal-to-noiseratio,whichisaveryimportantparameter,forovercomingnoisyenvironments.Thesignalgottenfromasatelliteisgenerallyveryweak.Theshapeofthetransmittedsignalaremosteasilyaffectedbythenoiseandattenuationintroducedbythecodec.

PASSAGETWOSofarwehaveassumedthateachvoicechannelhasaseparatecoder,theunitthatconvertssampledamplitudevaluestoasetofpulses;anddecoder,theunitthatperformsthereverseoperation.Thisneednotbeso,andsystemsareinoperationwhereasinglecodec(i.e.,coderanditsassociateddecoder)issharedbetween24,30,oreven120separatechannels.Ahigh-speedelectronicswitchisusedtopresenttheanaloginformationsignalofeachchannel,takeninturn,tothecodec.Thecodecisthenarrangedtosequentiallysampletheamplitudevalue,andcodethisvalueintothe8-digitsequence.Thustheoutput,tothecodecmaybeseenasasequenceof8pulsesrelatingtochannel1,thenchannel2,andsoon.Thisunitiscalledatimedivisionmultiplexer(TDM).Themultiplexingprinciplethatisusedisknownaswordinterleaving.Sincethewords,or8-digitsequences,areinterleavedintime.Atthereceiveterminalademultiplexerisarrangedtoseparatethe8-digitsequencesintotheappropriatechannels.Thereadermayask,howdoesthedemultiplexerknowwhichgroupof8-digitsrelatestochannel1,2,andsoon?Clearlythisisimportant.Theproblemiseasilyovercomebyspecifyingaframeformat,whereatthestartofeachframeauniquesequenceofpulsescalledtheframecode.Orsynchronizationwordisplacedsoastoidentifythestartoftheframe.Acircuitofthedemultiplexerisarrangedtodetectthesynchronizationword,andtherebyitknowsthatthenextgroupof8-digitscorrespondstochannel1.Thesynchronizationwordreoccursonceagainafterthelastchannelhasbeenreceived.

Atthereceiveterminalthereverseoperationtothemultiplexingisneededtoseparatethe8-digitsequencesintotheappropriatechannels.Thecodecinthetransmittingterminalistosampletheamplitudevalue,andcodethisvalueintothe8-digitsequence.Thedemultiplexerknowswhichgroupof8-digitsrelatestochannel1assoonasitfindsthesynchronizationword.Fromabovetext,weunderstandeachvoicechannelhasacoder.Thetimedivisionmultiplexerissocalledsincethereisaspecialwordcalledsynchronizationword.Hegroupof8-digitsfollowingthesynchronizationwordrelatestocharte11.

PASSAGETHREEByfarthemostpopularserialinterfacebetweenacomputeranditsCRTterminalistheasynchronousserialinterface.Thisinterfaceissocalledbecausethetransmitteddataandthereceiveddataarenotsynchronizedoveranyextendedperiodandthereforenospecialmeansofsynchronizingtheclocksatthetransmitterandreceiverisnecessary.Infact,theasynchronousserialdatalinkisaveryoldformofdatatransmissionsystemandhasitsoriginintheeraofteleprinter.Anasynchronousserialdatalinkissaidtobecharacter-oriented,asinformationistransmittedintheformofgroupsofbitscalledcharacters.Thesecharactersareinvariableunitscomprising7or8bitsof"information"plus2to4controlbitsandfrequentlycorrespondtoASCII-encodedcharacters.Themostcriticalaspectofthesystemisthereceivertiming.Thefallingedgeofthestartbittriggersthereceiver'slocalclock,whichsampleseachincomingbitatitsnominalcenter.SupposethereceiverclockwaitsT/2secondsfromthefallingedgeofthestartbitandsamplestheincomingdataeveryTsecondsthereafteruntilthestopbithasbeensampled.Asthereceiver'sclockisnotsynchronizedwiththetransmitterclock,thesamplingisnotexact.Themostobviousdisadvantageofasynchronousdatatransmissionistheneedforastart,parity,andstopbitforeachtransmittedcharacter.If7bitcharactersareused,theoverallefficiencyisonly70%.Alessobviousdisadvantageisduetothecharacter-orientednatureofthedatalink.Wheneverthed