活頁式教材微課版電子信息專業(yè)英語Chapter6CommunicationSystem通信系統(tǒng)

教學(xué)目標(biāo)6.1★調(diào)制與解調(diào)：掌握調(diào)制作用、信號與載波、模擬信號調(diào)制（調(diào)幅、調(diào)頻、調(diào)相）、采樣和編碼、數(shù)字信號調(diào)制、解調(diào)。★通過調(diào)制與解調(diào)、通信信道和多路復(fù)用、移動電話三篇文章學(xué)習(xí)通信系統(tǒng)。6.2★通信信道和多路復(fù)用：掌握通信信道作用、有線傳輸介質(zhì)（雙絞線、同軸電纜、光纖）、無線傳輸介質(zhì)（微波、通信衛(wèi)星）、多路復(fù)用作用、頻分復(fù)用、時分復(fù)用。6.3★移動電話：掌握移動電話功能和使用、移動電話組成、模數(shù)轉(zhuǎn)化、數(shù)字信號處理、CPU、存儲器、顯示屏。

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)NewWordsTechnicalTerms技術(shù)詞匯modulationn.調(diào)制；調(diào)整telecommunicationn.電信；遠程通信impressvt.施加于；給予印象carrierwave載波characteristicsn.特性，特征；特色inaccordancewith依照；與…一致altervt.改變，更改；vi.改變functionn.功能；函數(shù)；vi.運行sinusoidn.正弦曲線parametern.參數(shù)；系數(shù)magnituden.大小；量級；重要amplituden.振幅；豐富，充足termn.術(shù)語；學(xué)期；vt.叫做phasen.位相；階段；vt.定相suitableadj.適當(dāng)?shù)模幌嗯涞腶mplitudemodulation調(diào)幅；波幅調(diào)制frequencymodulation調(diào)頻；頻率調(diào)制phasemodulation調(diào)相；相位調(diào)制TechnicalTerms技術(shù)詞匯bandn.波段；樂隊atanyinstant在任何時刻immunityn.免疫力；免除distortionn.變形；失真；扭曲attheexpenseof以…為代價；支付費用bandwidthn.帶寬；頻帶寬度pulse-codemodulation脈沖編碼調(diào)制samplevt.取樣；抽樣；n.樣品compactdisc光碟，激光唱片quantizevt.量化；數(shù)字轉(zhuǎn)換amplitude-shiftkeying幅移鍵控frequency-shiftkeying頻移鍵控phase-shiftkeying相移鍵控finiteadj.有限的；限定的demodulationn.檢波；反調(diào)制；解調(diào)extractvt.提取；取出detectorn.檢測器；發(fā)現(xiàn)者；偵察器demodulatorn.解調(diào)器

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Inelectronicsandtelecommunications,modulationisatechniqueforimpressinginformation(

voice,music,picture,ordata

)onaradio-frequencycarrierwavebyvaryingoneormorecharacteristicsofthewaveinaccordancewiththesignal.Therearevariousformsofmodulation,eachdesignedtoalteraparticularcharacteristicofthecarrierwave.Ifwelookatageneralfunctionforasinusoid:f

(

t

)=Asin(

ωt+φ

).Wecanseethatthissinusoidhas3parametersthatcanbealtered,toaffecttheshapeofthegraph.Thefirstterm,A,iscalledthemagnitude,oramplitudeofthesinusoid.Thenextterm,ωisknownasthefrequency,andthelastterm,φisknownasthephaseangle.All3parameterscanbealteredtotransmitinformation.Thehighfrequencysinusoidalwavethatisusedinthemodulationisknownasthecarrier[4].Itisimportanttonoticethatasimplesinusoidalcarriercontainsnoinformationofitsown.Modulationisusedbecausethesomeinformationsignalsarenotsuitablefordirecttransmission,butthemodulatedsignalmaybemoresuitable.Text

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Inanalogmodulationsystems,varyingtheamplitude,frequency,orphaseofthecarrierresultsinamplitudemodulation(AM),frequencymodulation(FM),orphasemodulation(PM).Amplitudemodulation(AM)isthemodulationmethodusedintheAMradiobroadcastband.Inthissystem，theamplitudeofthecarrierwavevariesinaccordancewiththemodulatingsignal.Infrequencymodulation(FM),thefrequencyofthecarrierwaveisvariedinsuchawaythatthechangeinfrequencyatanyinstantisproportionaltothemodulatingsignal.Itsprincipalapplicationisalsoinradio,whereitoffersincreasednoiseimmunityanddecreaseddistortionovertheAMtransmissionsattheexpenseofgreatlyincreasedbandwidth.TheFMbandhasbecomethechoiceofmusiclistenersbecauseofitslow-noise,wide-bandwidthqualities;itisalsousedfortheaudioportionofatelevisionbroadcast.Phasemodulation,likefrequencymodulation,isaformofanglemodulation(socalledbecausetheangleofthesinewavecarrierischangedbythemodulatingwave).Text

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Inadigitalsignal,theinformationisencodedasasetofdiscretevalues.pulse-codemodulation(PCM)isamethodusedtodigitallyrepresentsampledanalogsignals.PCMhasbeenusedindigitaltelephonesystemsandisalsothestandardformfordigitalaudioincomputersandthecompactdiscformat.IntheFig.6-2diagram,asinewaveissampledandquantizedforpulse-codemodulation.Indigitalmodulation,acarrierwaveismodulatedbyadiscretesignal.Themostfundamentaldigitalmodulationtechniquesareamplitude-shiftkeying(ASK),frequency-shiftkeying(FSK),andphase-shiftkeying(PSK).Theparameterofthecarriersignalisshiftedbythediscreteamplitudesofthedigitalsignal(

Fig.6-3

).Demodulationistheactofextractingtheoriginalinformationsignalfromamodulatedcarrierwave.Eachtypeofmodulationisdifferentandrequiresdifferenttechniquestorecover(demodulate)theinformation.Forexample,forasignalmodulatedwithamplitudemodulation,wecanuseanenvelopedetector.Ontheotherhand,forasignalmodulatedwithanangularmodulation,wemustuseanFMdemodulatororaPMdemodulator.Differentkindsofcircuitsperformthesefunctions.Text

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Figures

Figure6-1Low-frequencyinformationsignal，AMradiowave，F(xiàn)MradiowaveFigure6-3Digitalsignal,ASK,FSK,PSKFigure6-2Samplingandquantizationofasignalfor4-bitPCM

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Ⅰ．Choosethebesttechnicaltermtocompletethefollowingstatements.ExercisesModulationisatechniqueforimpressinginformationonaradio-frequencycarrierwavebyvarying()ofthewaveinaccordancewiththesignal.A.amplitude B.frequency C.phase D.angleThesimplehighfrequencysinusoidalwavewhichcontainsnoinformationofitsownis().A.modulation B.generalfunction C.carrier D.transmission()isthemodulationmethodusedintheradiobroadcastsystem.A.AM B.FM C.PM D.PCMAttheexpenseofgreatlyincreasedbandwidth,()offersincreasednoiseimmunityanddecreaseddistortionintheradiobroadcast.A.amplitudemodulation

B.frequencymodulation C.phasemodulation D.musicmodulation

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Ⅰ．Choosethebesttechnicaltermtocompletethefollowingstatements.ExercisesPCMaudioisahighfidelity,uncompresseddigital()ofananalogaudiosignal.A.encoding B.sampling C.quantizing D.standardformIndigitalmodulation,()arefundamentaldigitalmodulationtechniques.A.PCM B.ASK C.FSK

D.PSK

6.1

Lesson16ModulationandDemodulation

調(diào)制與解調(diào)Ⅱ．TranslatethefollowingsentencesintoChinese.Exercises1．TheAmplitudeModulated(

AMradio

)carrierfrequenciesareinthefrequencyrange535-1605kHz.Carrierfrequenciesof540to1600kHzareassignedat10kHzintervals.2．TheFMradiobandisfrom88to108MHz.TheFMstationsareassignedcenterfrequenciesat200kHzseparationstartingat88.1MHz,foramaximumof100stations.3．ThesimplestandmostcommonformofASKoperatesasaswitch,usingthepresenceofacarrierwavetoindicateabinaryoneanditsabsencetoindicateabinaryzero.Thistypeofmodulationiscalledon-offkeying.4．Ifthecarrierfrequencybychangingthemethodtosendbinarysymbols,isthefrequencyshiftkeying(

FSK

)method,‘1’whenthereisalowfrequency,‘0’whenthereisahighfrequency.6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用NewWordsTechnicalTerms技術(shù)詞匯communicationchannel通信信道transmissionn.播送；傳遞mediumn.介質(zhì)；媒體median.介質(zhì)；媒質(zhì)wiredadj.有線的guidevt.引導(dǎo)；帶領(lǐng)n.指南twistedpairn.雙絞線coaxialcablen.同軸電纜opticalfibern.光纖，光導(dǎo)纖維electromagneticadj.電磁的propagatevt.傳播；傳送interferencen.干擾；干涉dielectricn.電介質(zhì)metallicadj.金屬的shieldn.防護物；vt.遮蔽electromagneticinterference電磁干擾coren.芯；核心；果心；要點TechnicalTerms技術(shù)詞匯capacityn.容量；能力lineofsight視線repeatern.中繼器；轉(zhuǎn)發(fā)器atintervals相隔一定距離（或時間）relayn.中繼；繼電器；v.轉(zhuǎn)播historicallyadv.歷史上地；從歷史觀點intercontinentaladj.洲際的；大陸間的telephonyn.電話（學(xué)）hand-heldadj.手持的，便攜式的terminaln.終端機uplinkn.上行鏈路downlinkn.下行鏈路multiplexingn.多路技術(shù)；v.多重發(fā)訊transmissionrate傳輸速度；傳輸率neighborhoodn.附近；鄰居megahertzn.兆赫kilohertzn.千赫6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用NewWordsTechnicalTerms技術(shù)詞匯carrierfrequency載波頻率adjacentstation鄰站；相鄰電臺allowancen.容差；津貼；允許frequency-divisionmultiplexing頻分多路復(fù)用allocatevt.分配；vi.指定TechnicalTerms技術(shù)詞匯recurringadj.循環(huán)的；重現(xiàn)的segmentn.段；v.分割slotn.（時）隙；狹縫；投硬幣口time-divisionmultiplexing時分多路復(fù)用hybridn.混合物；adj.混合的6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Acommunicationchannelisatransmissionmediumthatcarriesasignalbetweenthetransmitterandthereceiver.Transmissionmediaareclassifiedaswiredandwireless.Withwiredtransmissionmedia,thesignalsareguidedalongaphysicalpath,examplesofwiredmediaincludetelephonelines,twistedpaircables,coaxialcables,andopticalfibers.Withwirelesstransmissionmedia,electromagneticwavespropagatethroughtheair.Thetelephonelinesusedtocarrythevoiceanddatacommunicationsconsistofapairinsulatedcopperwires.Thewiresaretwistedaroundeachothertominimizeinterferencefromothertwistedpairsinthecable(Fig.6-4).Twistedpairsaretheleastexpensiveandmostwidelyusedtransmissionmediaforbothanaloganddigitalsignals.Acoaxialcablehasainnerconductorsurroundedbyanon-conductivedielectricinsulatingmaterial(Fig.6-5).Thedielectricissurroundedbymetallicshieldswhichformtheouterconductorandalsoshieldagainstelectromagneticinterference(EMI).Thetermcoaxialcomesfromtheinnerconductorandtheoutershieldsharingthesameaxis.Coaxialcableshavemorebandwidththantwistedpairs.Acoaxialcablecanhandle80timesasmanytelephonetransmissionsastwistedpairmedia.Andmanycomputersinlocalareanetworksarelinkedbycoaxialcables.Text6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Opticalfiberconsistsofacenterglasscoresurroundedbyseverallayersofprotectivematerials(Fig.6-6).Ittransmitslightratherthanelectronicsignalseliminatingtheproblemofelectricalinterference.Opticalfiberhastheabilitytotransmitsignalsovermuchlongerdistancesthancoaxialandtwistedpair.Ithas26,000timesthetransmissioncapacityoftwistedpairmedia.Italsohasthecapabilitytocarryinformationatvastlygreaterspeeds.Microwavetransmissiondiffersfromthepreviouslymentionedcommunicationschannelsinthatsignalistransmittedthroughtheairinsteadofthroughwiresorcables.Microwavetransmissionsoperateathighoperatingfrequenciesof3to10GHz.Thisallowsthemtocarrylargequantitiesofinformationduetothelargebandwidth.Microwavetransmissionislineofsighttransmission.Inordertoovercometheproblemoflineofsightandpoweramplificationofweaksignal,repeatersareusedatintervalsof25to30kilometersbetweenthetransmittingandreceivingend(Fig.6-7).Acommunicationsatelliteisamicrowaverelaystationplacedinouterspace.Insatellitecommunication,microwavesignalistransmittedfromatransmitteronearthtothesatelliteinspace.Thesatelliteamplifiestheweaksignalandtransmitsitbacktothereceiveronearth(Fig.6-8).ThemainadvantageofsatelliteText6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用communicationisthatitisasinglemicrowaverelaystationvisiblefromanypointofaverylargearea.Thefirstandhistoricallymostimportantapplicationforcommunicationsatelliteswasinintercontinentallongdistancetelephony.Theyarealsousedformobileapplicationssuchascommunicationstoships,vehicles,planesandhand-heldterminals,andforTVandradiobroadcasting.Multiplexingisaformofsignaltransmissioninwhichonecommunicationchannelcarriesseveraltransmissionsatthesametime.Thetelephonelinesthatcarryourdailyconversationscancarrythousandsorevenmoreofconversationsatatimeusingmultiplexing.Theexactnumberofsimultaneoustransmissiondependsonthetypeofcommunicationchannelandthedatatransmissionrate.Forexample,oneradiostationcanbroadcastradiowavesintofreespaceatfrequenciesintheneighborhoodof94.5MHz(megahertz)whileanotherradiostationcansimultaneouslybroadcastradiowavesatfrequenciesintheneighborhoodof96.1MHz.Eachradiostationwouldtransmitradiowavesoverafrequencybandwidthofabout180kHz(kilohertz),centeredatfrequenciessuchastheabove,whicharecalledthe‘carrierfrequencies’.Eachstationinthisexampleisseparatedfromitsadjacentstationsby200kHz,andthedifferencebetween200kHzand180kHz(20kHz)isanengineeringallowanceinthecommunicationsystem.Text6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Intheexampleabove,the‘freespacechannel’hasbeendividedintocommunicationschannelsaccordingtofrequencies,andeachchannelisassignedaseparatefrequencybandwidthinwhichtobroadcastradiowaves.Thissystemofdividingthemediumintochannelsaccordingtofrequencyiscalled‘frequency-divisionmultiplexing’(FDM)(Fig.6-9).Anotherwayofdividingacommunicationsmediumintochannelsistoallocateeachsenderarecurringsegmentoftime(a‘timeslot’,forexample,20millisecondsoutofeachsecond),andtoalloweachsendertosendmessagesonlywithinitsowntimeslot.Thismethodofdividingthemediumintocommunicationchannelsiscalled‘time-divisionmultiplexing’(TDM)(Fig.6-10),andisusedinopticalfibercommunication.SomeradiocommunicationsystemsuseTDMwithinanallocatedFDMchannel.Hence,thesesystemsuseahybridofTDMandFDM.Text6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Figures

Figure6-4TwistedpairwiringFigure6-7Microwavetransmission

Figure6-5CoaxialcableFigure6-6Opticalfiber6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Figures

Figure6-8SatellitecommunicationFigure6-9FDMFigure6-10TDM6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Ⅰ．Decidewhetherthefollowingstatementistrueorfalse,andexplainyouranswers.Exercises1．Transmissionmediaincludetelephonelines,twistedpaircables,coaxialcables,opticalfibers,microwavetransmissions,satellitetransmissions,andcellularradiosystems.2．Twistedpairshavefewerbandwidththancoaxialcableoropticalfiber.3．Coaxialcablesareusedtotransmitbothanaloganddigitalsignal.Theyhavesuperiorfrequencycharacteristicscomparedtotwistedpair,andtheycansupporthigherfrequenciesanddatarates.4．Amajoradvantageofopticalfibermediaisnotsusceptibletoelectronicinterference.Therefore,theyareamorereliableformofdatatransmission.5．OpticalFibercablesaresignificantlylessexpensivethancoaxialcable.Adisadvantageofopticalfiberchannelsisthattheycannotcarryinformationovergreatdistances.6．Microwavesarehigh-frequencyradiowavesthatcanonlybedirectedinstraightlines.Consequently,formicrowavetransmissionstobeabletooccuroverlargerdistances,datamessagesmustberelayedfromonelocationtoanotherusingantennasplacedathighaltitudes.6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Ⅰ．Decidewhetherthefollowingstatementistrueorfalse,andexplainyouranswers.Exercises7．Acommunicationsatelliteisusedtolinktwoormoreground-basedmicrowavetransmitters/receivers.Thesatellitereceivestransmissionsononefrequencyband(uplink),amplifiesorrepeatsthesignal,andtransmitsitonanotherfrequency(downlink).8．FDM(

FrequencyDivisionMultiplexing

)andTDM(

TimeDivisionMultiplexing

)aretwomethodsofmultiplexingmultiplesignalsintoasingletransmissionchannel.6.2 Lesson17CommunicationChannelandMultiplexing

通信信道和多路復(fù)用Ⅱ．TranslatethefollowingsentencesintoChinese.Exercises1．Thesetwisted-pairinstallationsaregenerallydesignedtosupportvoicetrafficusinganalogsignaling.However,byusingamodem,theycanalsohandledigitaldata.2．Coaxialcableisusedasatransmissionlineforradiofrequencysignals.Itsapplicationsincludefeedlinesconnectingradiotransmittersandreceiverswiththeirantennas,anddistributingcabletelevisionsignals.3．Infiber-opticcommunication,thelightformsanelectromagneticcarrierwavethatismodulatedtocarryinformation.Becauseofitsadvantagesoverelectricaltransmission,opticalfibershavelargelyreplacedcopperwirecommunicationsincorenetworks.4．Communicationssatellitesareofteningeostationaryorbit.Atthehighorbitalaltitudeof35,800kilometers,ageostationarysatelliteorbitstheEarthinthesameamountoftimeittakestheEarthtorevolveonce.5．Inanalogtransmission,signalsarecommonlymultiplexedusingfrequency-divisionmultiplexing(

FDM

),inwhichthecarrierbandwidthisdividedintosubchannelsofdifferentfrequencywidths,eachcarryingasignalatthesametimeinparallel.6．Indigitaltransmission,signalsarecommonlymultiplexedusingtime-divisionmultiplexing(

TDM

),inwhichthemultiplesignalsarecarriedoverthesamechannelinalternatingtimeslots.

6.3

Lesson18MobilePhone

移動電話NewWordsTechnicalTerms技術(shù)詞匯mobileadj.移動的；n.移動物體cellphone手機duplexn.雙工basestation基站publictelephone公用電話網(wǎng)networkfixedline固定線路antennan.天線outgoingadj.外出的incomingadj.引入的DSP數(shù)字信號處理器signal-manipulation信號處理choren.家庭雜務(wù)；日常零星事務(wù)commandv.命令，指揮；n.命令operatingsystem操作系統(tǒng)commitvt.致力于，承諾，從事customizableadj.可定制的TechnicalTerms技術(shù)詞匯directoryn.目錄；姓名地址錄rechargevt.再充電；再控告internaladj.內(nèi)部的；內(nèi)在的flashmemory閃速存儲器SIMcard用戶識別卡；智能卡service-subscribern.服務(wù)訂戶；服務(wù)用戶keyn.鑰匙；密鑰；關(guān)鍵slidevt.滑動；使滑動featuren.特色，特征；v.特寫built-inadj.嵌入的；n.內(nèi)置incorporatevt.包含，吸收；合并webbrowser

瀏覽器smartphonen.智能手機resolution

n.[物]分辨率；決議；解決；決心touchscreenn.觸摸屏optimizedadj.最佳化的6.3

Lesson18MobilePhone

移動電話Amobilephone(alsocalledmobileorcellphone)isanelectronicdeviceusedforfullduplextwo-wayradiotelecommunicationsoveracellularnetworkofbasestations(Fig.5-3).Amobilephoneallowsitsusertomakeandreceivetelephonecallstoandfromthepublictelephonenetworkwhichincludesothermobilesandfixedlinephonesacrosstheworld.Cellphonecontainsafewindividualparts:Anamazingcircuitboardcontainingthebrainsofthephone,antenna,aLiquidCrystalDisplay(LCD),akeyboard,amicrophone,aspeakerandabattery(Fig.5-4).Thecircuitboardistheheartofthesystem.HereisonefromatypicalNokiadigitalphone(Fig.5-5,Fig.5-6).Inthephotos,thereareseveralchips.Theanalog-to-digitalanddigital-to-analogconversionchipstranslatetheoutgoingaudiosignalfromanalogtodigitalandtheincomingsignalfromdigitalbacktoanalog.Thedigitalsignalprocessor(DSP)isahighlycustomizedprocessordesignedtoperformsignal-manipulationcalculationsathighspeed.Themicroprocessorhandlesallofthechoresforthekeyboardanddisplay,dealswithcommandandcontrolsignalingwiththebasestationandalsocoordinatestherestofthefunctionsontheboard.Text6.3

Lesson18MobilePhone

移動電話TheROMandFlashmemorychipsprovidestorageforthephone’soperatingsystemandcustomizablefeatures,suchasthephonedirectory.Thepowersectionhandlespowermanagementandrecharging.Finally,theRFamplifiershandlesignalstravelingtoandfromtheantenna.Somephonesstorecertaininformation,ininternalFlashmemory,whileothersuseexternalcardssuchasSIMcard(Fig.5-7).TheSIMstorestheservice-subscriberkeyusedtoidentifyasubscriberonmobiledevice.TheSIMcardmakesiteasytoswitchtoanewphonebysimplyslidingtheSIMoutoftheoldphoneandintothenewone.Thedisplay(Fig.5-8)hasgrownconsiderablyinsizeasthenumberoffeaturesincellphoneshaveincreased.Mostcurrentphonesofferbuilt-inphonedirectories,calculatorsandgames.Andmanyofthephonesincorporatewebbrowser.Asmartphoneisamobilephonebuiltonamobileoperatingsystem.Smartphonestypicallyaddedthefunctionsofpersonaldigitalassistant(PDA)，portablemediaplayers,digitalcameras,andGPSnavigationunitstoformonemulti-usedevice.Modernsmartphonesalsoincludehigh-resolutiontouchscreensandwebbrowsersthatdisplaystandardwebpagesaswellasmobile-optimizedsites.High-speeddataaccessisprovidedbyWi-FiandMobileBroadband.Text6.3

Lesson18MobilePhone

移動電話Figures

Figure5-3Cellularnetwork6.3

Lesson18MobilePhone

移動電話Figures

Figure5-5PCBFront

Figure5-4PartsofacellphoneFigure5-8Display&keypadFigure5-7SIMcardFigure5-6PCBBack6.3

Lesson18MobilePhone

移動電話Ⅰ．Decidewhetherthefollowingstatementistrueorfalse,andexplainyouranswers.Exercises1．Amobilephoneusercanonlymakecallstoothermobilesandonlyreceivetelephonecallsfromthefixedlinephones.2．Mobilephonecontainsabrain,aheart,acircuitboard,anantenna,aLCD,akeyboard,amicrophone,aspeakerandabattery.3．Thereareanalog-to-digitalanddigital-to-analogconversionchips,DSPchip,microprocessorchip,ROMandFlashmemorychips,andotherchipsonthecircuitboard.4．BothamicroprocessorandaDSPcanperformdigitaldataoperations.ButamicroprocessorcannotbeasgoodasaDSPwhenitcomestomathematicalfunctions.5．SIMcardstoresthephone’soperatingsystemandotherinformation,suchasthephonedirectory.6．Thelargerthedisplayscreenis,themorefeaturesthecellphoneshave.6.3

Lesson18MobilePhone

移動電話Ⅱ．TranslatethefollowingsentencesintoChinese.Exercises1．Amobilephoneisalsocalledacellphonebecausethephonenetworkismadeupofbasestationsthatsendoutsignals,andtheareacoveredbyeachofthesebasestationsiscalledacell.2．Amobilephonesendsandreceivesinformationbyradiocommunication.Radiofrequencysignalsaretransmittedfromthephonetothenearestbasestation.Basestationslinkmobilephonestotherestofthemobileandfixedphonenetwork.3．Ifapersonwithamobilephonestartstomoveoutofonecellandintoanother,thecontrollingnetworkhandsovercommunicationstotheadjacentbasestation.4．Thedigital/analogconversioncircuitenablesthevoicetobeconvertedfromanalogtodigitalforthesendpath,andfromdigitaltoanalogforthereceivepath.6.4 Grammar

科技英語名詞性從句狀語從句及翻譯技巧名詞性從句在主從復(fù)合句中擔(dān)當(dāng)主語、賓語、表語或同位語的從句分別稱為主語從句、賓語從句、表語從句或同位語從句。這些從句在句中的作用相當(dāng)于名詞在句中所起的作用，因此統(tǒng)稱為名詞性從句。Grammar引導(dǎo)名詞性從句的關(guān)聯(lián)詞It’sstillaquestionwhetherhecanbuyarailwayticket.他能否買到火車票仍然是個問題。主語從句Thatthemoonmovesroundtheearthiswellknowntoallofus.月球環(huán)繞地球轉(zhuǎn)動，這是我們大家都熟知的。賓語從句Sheexplainedwhyshecamelate.她解釋她為什么來遲了。表語從句ThereasoniswhathasalreadybeenstatedinChapterⅡ.原因就是在第二章里已經(jīng)談過的。同位語從句Einsteincametotheconclusionthatthemaximumspeedpossibleintheuniverseisthatoflight.愛因斯坦得出的結(jié)論是：宇宙中可能的最快速度即光速。6.4 Grammar

科技英語名詞性從句狀語從句及翻譯技巧狀語從句在復(fù)合句中起狀語作用的從句叫狀語從句，修飾主句中的動詞、形容詞或副詞等。狀語從句按其意義可分為時間、地點、原因、目的、結(jié)果、條件、比較、方式、讓步等九種。Grammar時間狀語從句Whenshecomes，Ishalltellhertowaitforyou.她來的時候我將告訴她讓她等你。地點狀語從句Youhavetherighttolivewhereyouwant.你有權(quán)居住在你想住的地方。原因狀語從句Shehasjustmissedherbusbecausethetimetablehaschanged.因為汽車時刻表變了，她沒有趕上汽車。目的狀語從句結(jié)果狀語從句條件狀語從句比較狀語從句方式狀語從句讓步狀語從句EvaluationofLearningEffect學(xué)習(xí)效果自我評價EvaluationContents（內(nèi)容）Master（掌握）AlmostMaster（基本掌握）Incapable（未掌握）NewWordsandTechnicalTerms(單詞專業(yè)術(shù)語)Text(課文）Grammar（語法）Exercises（練習(xí)）感謝觀看ThanksforWatching活頁式教材微課版電子工業(yè)出版社電子信息專業(yè)英語Chapter7ComputerTechnology計算機技術(shù)

教學(xué)目標(biāo)7.1★計算機硬件：掌握計算機硬件組成、主板、CPU、內(nèi)存、硬盤、顯示器、鼠標(biāo)、鍵盤。★通過計算機硬件、操作系統(tǒng)、計算機網(wǎng)絡(luò)三篇文章學(xué)習(xí)計算機技術(shù)。7.2★操作系統(tǒng)：掌握操作系統(tǒng)功能、圖型界面操作系統(tǒng)和命令行操作系統(tǒng)、計算機操作系統(tǒng)和手機操作系統(tǒng)、嵌入式操作系統(tǒng)。7.3★計算機網(wǎng)絡(luò)：掌握計算機網(wǎng)絡(luò)功能、局域網(wǎng)、廣域網(wǎng)、以太網(wǎng)網(wǎng)絡(luò)協(xié)議、Internet網(wǎng)。7.1

Lesson19ComputerHardware

計算機硬件NewWordsTechnicalTerms技術(shù)詞匯hardwaren.計算機硬件；五金器具softwaren.軟件stuffn.材料；填充物；vt.塞滿monitorn.監(jiān)視器；班長；vt.監(jiān)控motherboardn.母板；主板peripheraln.外圍設(shè)備；adj.外圍的expansionslot擴展槽，擴充插槽TechnicalTerms技術(shù)詞匯alternativelyadv.二者擇一地；作為一種選擇carryoutvt.執(zhí)行，實行；貫徹；實現(xiàn)instructionn.指令，命令；指示；用法說明arithmeticaladj.算術(shù)的；算術(shù)上的volatileadj.揮發(fā)性的；n.揮發(fā)物tensofbillions數(shù)百億byten.字節(jié)7.1

Lesson19ComputerHardware

計算機硬件Computerisasystem,consistingofmanycomponents.Someofthosecomponents,likeWindowsXP,andallotherprograms,aresoftware.Thestuffyoucanactuallyseeandtouchishardware.Computerhardwarecomprisesallofthephysicalpartsofthecomputersuchassystemunit,monitor,keyboard,mouse,speaker,andothers,asshowninFig.7-1.Thesystemunithasmotherboard,CPU,harddisk,RAM,CD-ROM,asshowninFig.7-2.Thesystemunitistheactualcomputer;everythingelseiscalledaperipheraldevice.Motherboard

–

ThemotherboardisthemaincircuitboardinsidethePC（Fig.7-3）.ItholdstheCPUandmemory,providesexpansionslotsforperipherals,andwhetherdirectlyorindirectlyconnectstoeverypartofthePC.Themotherboardissometimesalternativelyknownasthemainboard,systemboard.CPU

–

CPUorCentralProcessingUnitisthebrainofthecomputer.CPUcarriesouttheinstructionsofacomputerprogram,toperformthebasicarithmetical,logical,andinput/outputoperationsofthesystem[4].TheperformanceofthecomputerisdeterminedbytheCPUchip.Currently,theIntelprocessorchipisthemostpopulareventhoughthereareotherchipsavailableinthemarkettodaysuchasAMDandothers.Text7.1

Lesson19ComputerHardware

計算機硬件RAM

–

RAMorRandomAccessMemoryisamemorythatisbeingusedbythecomputertostoretheinformationtemporarily.ForexamplewhensomeworkisperformedonsomeapplicationsthatworkistemporarilystoredintheRAM.TheadvantageusingRAMtostoredataisthatRAMisveryfast.HardDisk

–

Alloftheinformationisstoredonthecomputer’sharddisk.UnlikeRAM,whichisvolatile,the