《专业英语》-4. 教材中习题及答案

Lesson1AnalogandDigitalSignalWhatisananalogsignal?Ananalogsignalisonehavingcontinuousvalues.Whatisthecharacterofadigitalsignal?Foronething,digitaldatacanbeprocessedandtransmittedmoreefficientlyandreliablythananalogdata.Also,digitaldatahasagreatadvantagewhenstorageisnecessary.Noise(unwantedvoltagefluctuations)doesnotaffectdigitaldatanearlyasmuchasitdoesanalogsignals.3、Howisthesoundsignalbesavedinthedigitalcircuit?Musicindigitalformisstoredonthecompactdisk.Alaserdiodeopticalsystempicksupthedigitaldatafromtherotatingdiskandtransfersittothedigital-to-analogconverter(DAC).TheDACchangesthedigitaldataintoananalogsignalthatisanelectricalreproductionoftheoriginalmusic.Thissignalisamplifiedandsenttothespeakerforyoutoenjoy.WhenthemusicwasoriginallyrecordedontheCD,aprocess,essentiallythereverseoftheonedescribedhere,usingananalog-to-digitalconverter(ADC)wasused.Lesson2ApplicationofOhm’sLawWhatisaseriescircuit?Aseriescircuitisoneinwhichthecurrentflowsinasinglecontinuouspathandisofthesamevalueateverypointincircuit.Whatisthecharacteristicofaparallelcircuit?Inaparallelcircuittherearetwoormorecurrentpathsbetweentwopointsinthecircuit.HerethecurrentdividesatB,partgoingthroughR1,andpartthroughR2,andcombinesatAtoreturntothebattery.3.Howtocalculatethecurrentinthesethreekindsofcircuit?R1ERR1ER2R1RR1R2AB－＋－＋R1R2R－＋R1R2R3R4ABLesson3TheNANDGateWhatistheuseoftheNANDgate?Ifallinputsarehighlevel(1),thentheoutputislowlevel(0);Ifatleastoneoftheinputsislow(0),thentheoutputishigh(1).Howtodetectthreesignalswhicharealllow?UseanNORgate.Whenallthethreeofthegateinputsarelowlevel,theoutputishighlevel3.Whytwodifferentgatescouldbeusedinasamecircuit?Equivalent.Lesson4TheDesignofICLayoutWhatisIntegratedCircuit?Aseveryoneknows,theintegratedcircuitisasinglecomponentincludingalargenumberofactiveandpassivedevicesandtheirinterconnectionstorealizecomplexfunctions.HowtodesigntheIC?Firstyoudesignyourlogic,synthesizeit,draftafloor-plan,andthendosometimingchecksaroundthatloopforwhile.TheseVHDLdatafilesarethensubmittedtoacomputersimulator,whichteststhechipcircuitrywhileitisstillinsoftwareform.Thenyourunyourplaceandroutetoolsanddosometimingchecks.Finally,youruntheDRCandLVSchecksagainstthenetlistyoustartedwith,outofyourlogicsynthesis.Thenyougetthefinalchipdone.3、Whatislayout,andhowtodesignit?Integratedcircuitlayoutisadescriptionoftheplanargeometricshapeoftheactualphysicalsituationofintegratedcircuits.ThelayoutdesignisgettingtheICdesignontosilicon,theplaceandroutetoolscanhelpus.Lesson5ManufacturingProcessofSemiconductorWhatistheMoore’sLaw?In1965,GordonMoorenotedthatthenumberoftransistorsonachipdoubledevery18to24months.Hemadeapredictionthatsemiconductortechnologywilldoubleitseffectivenessevery18months.WhatarethestagesofICfabrication?ThefivestagesofICfabricationare:Waferpreparation:siliconispurifiedandpreparedintowafers.Waferfabrication:microchipsarefabricatedinawaferfabbyeitheramerchantchipsupplier,captivechipproducer,fablesscompanyorfoundry.Wafertest:Eachindividualdieisprobedandelectricallytestedtosortforgoodorbadchips.Assemblyandpackaging:Eachindividualdieisassembledintoitselectronicpackage.(5)Finaltest:EachpackagedICundergoesfinalelectricaltest.3、Whatarethekeysemiconductortrends? Keysemiconductortrendsare:(1)Increaseinchipperformancethroughreducedcriticaldimensions(CD),morecomponentsperchip(Moore’slaw,whichpredictsthedoublingofcomponentsvery18-24months)andreducedpowerconsumption. (2)Increaseinchipreliabilityduringusage.(3)Reductioninchipprice,withanestimatedpricereductionof100milliontimesforthe50yearspriorto1996.Lesson6ThePackageTechnologyofICWhatisthepackaging?ICpackagingenclosesthedieinaprotectivepackage.Whatistheassembly?ICfinalassemblyseparateseachgooddiefromthewaferandattachesthedietoametalleadframeorsubstrate.WhataretheICpackagingfunctions?ICpackaginghasfourfunctions:protectionfromtheenvironment/handling,signalinterconnections,physicalsupportandheatdissipation.Lesson7CellphoneCommunication1Pleasebrieflysummarytheprocessofcommunicationoftwomobilephones.microphonemicrophoneA/DCodingmodulationAntenna1NoisechannelAntenna2AmplifyDemodulaitionDecodingD/ASpeaker2Whatismodulation?Modulationisjustspectrumshifting.Thatistosay,modulationistheprocessofshiftingspectrumofonecenterfrequencytoanother.3Whatisdemodulation?Demodulationistheactofextractingtheoriginalinformation-bearingsignalfromamodulatedcarrierwave.Lesson8ImageSensorsHowdoesthedigitalcameracapturetheimage?Digitalcamerasuseasolid-statedevicecalledanimagesensortocaptureimages.Whatarethetypesofimagesensors?CCD,CMOS3、Whataretheadvantagesofthetwokindsimagesensors?CCD:goodimagingqualityCMOS:lowcostLesson9VirtualRealityWhatisvirtualreality?Virtualreality(VR)isaninteractivecomputer-generatedexperiencetakingplacewithinasimulatedenvironment,thatincorporatesmainlyauditoryandvisual,butalsoothertypesofsensoryfeedbacklikehaptic.Whatisthecharacteristicsofvirtualreality?Polyesthesia,existencesense,interactivity,autonomy3.Whatistheapplicationofvirtualreality?(1)Entertainment(2)Medicine(3)Interiordesign(4)Realestatedevelopment(5)Emergencydrill(6)Industrialsimulation(7)MilitaryandaerospaceLesson10UnmannedAerialVehicleWhatkindsofunmannedaerialvehiclescanbeclassified?ClassificationFlightmodeFixedwingUAV,rotorwing(propeller,multirotor)UAV,umbrellawingUAV,flappingwingUAV,unmannedairshipUAVVolumeweightMiniatureUAV:<severalkilograms,SmallsizeUAV:<200KgMediumsizeUAV:200-500kg,LargeUAV:>500KgDistanceShortrangeUAV:5-50km,ShortrangeUAV:50-200km;MediumrangeUAV:200-800km,RemoteUAV:>800KmApplicationMilitaryUAV,civilianUAVFlightheightUltra-lowaltitudeUAV:0-100m,LowaltitudeUAV:100-1000m,HollowUAV:1000-7000m,AltitudeUAV:7000-18000m,SuperhighaltitudeUAV:>18000mWhataretheworkflowsoftheunmannedaerialvehicles?(1)Startinterface:realizetheplanningofthetaskquickly,enterthetaskmonitoringinterface,realizethefastautomaticfilingoftheaerialtask,dividethefunctions,andrealizethespecialandstableoperationofthesoftware.(2)Pre-flightinspection:inordertoensurethesafetyofthetask,automatictestingiscarriedoutwithflightcontrolsoftwarebeforetakeofftoensurethattheaircraft'sGPS,compass,airspeedtubeanditspitchingrollareingoodcondition,soastoavoidthedangeroussituationintheaerial.(3)Flightmissionplanning:flightmissionplanningiscarriedoutinthreemodesofregionalaerialphotography,navigationandblending.(4)Flightmonitoring:mastertheattitude,orientation,airspeed,position,batteryvoltage,real-timewindspeed,winddirection,andmissiontimeoftheaircraftinrealtime,soastofacilitateoperatorstojudgethefeasibilityofthetaskinrealtimeandfurtherensurethesafetyofthetask.(5)Imagestitching:aftertheaerialmissioniscompleted,navigationaerialimagesareusedforimagestitchingintheresearcharea.3.Whataretheapplicationsofunmannedaerialvehicles?(1)Scientificresearch.(2)Journalism.(3)Cargotransport.(4)Agriculture.(5)Trafficsurveillance.(6)Disasterrelief.Lesson11BluetoothWhatisBluetoothtechnology?Bluetoothtechnologyisauniversalradiointerfaceinthe2.45GHzfrequencybandthatenablesportableelectronicdevicestoconnectandcommunicatewirelesslyviashort-range,adhocnetwork.Eachunitcansimultaneouslycommunicatewithuptoseveralotherunitsperpiconet.Moreover,eachunitcansimultaneouslybelongtoseveralpiconets.WhataretheadvantagesoftheBluetooth?1Ms/ssymbolrateexploitsmaximumavailablechannelbandwidth;Fastfrequencyhoppingavoidsinterference;Adaptiveoutputpowerminimizesinterference;Shortdatapacketsmaximizeinterference;Fastacknowledgeallowslowcodingoverheadforlinks;Flexiblepackettypessupportwideapplicationrange;Airinterfacetailoredtominimizecurrentconsumption;CVSD(continuousvariableslopedeltamodulation)voicecodingenablesoperationathighbiterrorrates.3、WhataretheapplicationsoftheBluetooth?Bluetoothtechnologyisfreeforallthepeople.Itworksin2.4GHzbandwithoutlicensing,andcanbeusedinindustrial,technology,medicine(ISM).Theproductsintegratedthetechnology,frommobilephones,carstothemedicalequipment,moreover,theusersfromconsumers,industrialmarketstoenterprises,aretoonumeroustomentiononebyone.Bluetoothisanimmediatetechnique,itdoesnotrequirearegularinfrastructure,andeasytoinstallationandsetup.Lesson12WirelessLANWhatisBSS?BSS:BaseStationSubsystem基站子系统WhatisIBSS?IBSS:IndependentBasicServiceSet独立基站服务子集3、WhatisESS?ESS:ExtendedServiceSet扩展服务集合Lesson13The4thGenerationmobilecommunication(4G)WhatisthedifferencebetweenFDD-LTEandTD-LTE?TheupanddowndataofFDD-LTEaretransmittedatthesametime,liketwolanerunning.Uplinkanddownloadingcanbecarriedoutsimultaneously.TheupanddowndataofTD-LTEaretransmittedseparately,likesinglelanerunning.Throughthe"signallight"controlchannelforuploadingordownloading,uploadanddownloadcannotrunatthesametime.Whatrequirementsmustbefulfilledfor4G?• Bebasedonanall-IPpacketswitchednetwork.• Havepeakdataratesofuptoapproximately100Mbit/sforhighmobilitysuchasmobileaccessanduptoapproximately1Gbit/sforlowmobilitysuchasnomadic/localwirelessaccess.• Beabletodynamicallyshareandusethenetworkresourcestosupportmoresimultaneoususerspercell.• Usescalablechannelbandwidthsof5–20MHz,optionallyupto40MHz.• Havepeaklinkspectralefficiencyof15-bit/s/Hzinthedownlink,and6.75-bit/s/Hzintheuplink(meaningthat1Gbit/sinthedownlinkshouldbepossibleoverlessthan67MHzbandwidth).• Systemspectralefficiencyis,inindoorcases,3-bit/s/Hz/cellfordownlinkand2.25-bit/s/Hz/cellforuplink.• Smoothhandoversacrossheterogeneousnetworks.Whatarethecharacterof4G?(1)Fastcommunicationspeed(2)Widenetworkspectrum(3)Flexiblecommunication(4)Highintelligentperformance(5)LowcostLesson14The5thGenerationmobilecommunication(5G)Whatis5G?5G,thefifthgenerationmobilephonemobilecommunicationstandard,isalsocalledthefifthgenerationmobilecommunicationtechnology.Whataretheadvantageof5G?HighspeedLowlatencyHighcapacityWhatchangeswill5Gbringtous?Whenyougetupinthemorning,thebedroomlightsandcurtainsopenautomatically.Youentersthebathroom,thewaterhasbeenadjustedtotherighttemperatureautomatically.Thedigitaltoothbrushrecordsanduploadsthereal-timedataofyourteethandmouth.Withwearingglasses,thewifeandchildareontheirwaytoschool,andthechildiswavingtoyoutosaygoodmorningthroughthevirtualrealityontheglasses.Afterbreakfast,withafewblinks,thecartakesyoutotheroadandstartsthevideomeeting.Ifadocumentisforgottenwithabusinesstrip,youcanfindthefilethroughthenetworkcontrolofthehomemonitoringdeviceimmediately.Themanipulationoftheintelligentrobotcanscanandsenttoyou."Fetchfromadistance"areeasyandconvenient.Lesson15LightFidelityWhatistheworkingprincipleofLiFi

?Thisopticalwirelesscommunications(OWC)technologyuseslightfromlight-emittingdiodes(LEDs)asamediumtodelivernetworked,mobile,high-speedcommunicationinasimilarmannertoWiFi.Visiblelightcommunications(VLC)worksbyswitchingthecurrenttotheLEDsoffandonataveryhighrate,tooquicktobenoticedbythehumaneye.AlthoughLiFiLEDswouldhavetobekeptontotransmitdata,theycouldbedimmedtobelowhumanvisibilitywhilestillemittingenoughlighttocarrydata.Thelightwavescannotpenetratewallswhichmakesamuchshorterrange,thoughmoresecurefromhacking,relativetoWiFi.ComparedwithWiFi,whatarethecharacteristicsoftheLiFi?LiFiWiFiSpeedVeryHighModerateDataDensityVeryHighLowSecurityVeryHighModerateDataProtectionVeryHighLowTransmissionpowerVeryHighModerateReliabilityModerateModerateRangeLowModerateEco-ImpactLowModerateDeviceConnectivityVeryHighHighObstacleInterferenceVeryHighLowFamiliarityLowVeryHigh3.WhataretheapplicationofLiFi?UnderwaterapplicationHospitalVehiclesIndustrialautomationAviationDangerousenvironmentLocationBasedService(LBS)Lesson16TheuseofmultimeterHowtoselectanappropriatemeasuringrange?Theselectedrangeisclosetothemeasuredvalue.Couldyouexchangetheblackprobeandtheredprobewhenyoumeasurevoltage？andwhy？NO.Itisdirectional.3.Indailylife，wheremayyoutakeuseofmultimeters？andhow？Multimeterisveryuseful,itcandoresistance-testing,besidescontinuity-testingandvoltage-testing.Lesson17oscilloscope1.Whatisthemainfunctionoftheoscilloscope?Themainfunctionoftheoscilloscopeistocalculatethefrequencydifference.2.Canyoubrieflysummarythetipsofmeasuringfrequencyofasignal？TurnonpowerCheckandadjustmentbeforeusingoscilloscopeSelectcouplingmodeSelectsensitivityofyaxisSelectthesourceoftriggeringsignalsandpolaritySelectscanningspeedInput\o"查找:measuredsignal"measuredsignal3.Inreality,pleas