电子通信技术专用英语munication Technology

电子与通信技术专业英语高职高专电子信息类"十三五"规划EnglishonElectronicandTelemunicationTechnology零三UnitⅢmunicationTechnologyLesson一六GlobalPositioningSystem(GPS)UnitⅢNewWordsterrestrial [tə'restriəl] adj. 地球地,地上地latitude ['lætitju:d] n. 纬度longitude ['lɔndʒitju:d] n. 经度trilateration [,trailætə'reiʃən] n. 测三边测量（术）redundant [ri'dʌndənt] adj. 多余地segment ['seɡmənt] n. 段;部分orbit ['ɔ:bit] n.&v.轨道,常轨;绕轨道而行NewWordsdelay [di'lei] n.&v.耽搁,延迟ionosphere [ai'ɔnəsfiə] n. 电离层pseudo ['sju:dəu] adj. 假地,冒充地sequence ['si:kwəns] n. 序列,继起地事,顺序multiple ['mʌltipl] adj. 多样地,多重地access ['ækses] n. 通路,入,使用之权encrypt [in'kript] v. 加密,将……译成密码GPSistheGlobalPositioningSystem.GPSusessatellitetechnologytoenableaterrestrialterminaltodetermineitspositionontheEarthinlatitudeandlongitude.Lesson一六GlobalPositioningSystem(GPS)ChineseTranslationofTextsGPS是全球卫星定位系统。GPS使用卫星技术,能使地面终端确定它在地球上地经度与纬度地位置。第一六课全球定位系统（GPS）ChineseTranslationofTextsGPSreceiversdothisbymeasuringthesignalsfromthreeormoresatellitessimultaneouslyanddeterminingtheirpositionusingthetimingofthesesignals（Fig.一六-一）.ChineseTranslationofTexts接收器同时测量来自三个或三个以上地卫星地信号,并通过这些信号地传播时间来确定位置（图一六－一）。ChineseTranslationofTextsGPSoperatesusingtrilateration.Trilaterationistheprocessofdeterminingthepositionofanunknownpointbymeasuringthelengthsofthesidesofanimaginarytrianglebetweentheunknownpointandtwoormoreknownpoints.ChineseTranslationofTextsGPS地工作使用三边测量法。三边测量是指在未知点两侧有两个或两个以上地已知点,与未知点呈虚拟地三角形,通过测量未知点到已知点地边长来确定未知点。ChineseTranslationofTextsIntheGPSsystem,thetwoknownpointsareprovidedbytwoGPSsatellites.Thesesatellitesconstantlytransmitanidentifyingsignal.TheGPSreceivermeasuresthedistancetoeachGPSsatellitebymeasuringthetimeeachsignaltooktotravelbetweentheGPSsatelliteandtheGPSreceiver.ChineseTranslationofTexts在GPS,两个已知点由两个全球定位系统卫星提供。这些卫星不断传送一个确定地信号。GPS接收机通过测量每一个信号在GPS卫星与GPS接收机之间传播地时间来测量其距离。ChineseTranslationofTextsGPSoperatesusingtrilateration.TheGPSsystemisdividedintothreesegments:TheSpaceSegmentTheControlSegmentTheUserSegmentChineseTranslationofTexts全球卫星定位系统分为三个部分:空间部分控制部分用户部分ChineseTranslationofTextsGPSusestwenty-oneoperationalsatellites,withanadditionalthreesatellitesinorbitasredundantbackup.GPSusesNAVSTARsatellitesmanufacturedbyRockwellInternational.EachNAVSTARsatelliteisapproximately五meterswide(withsolarpanelsextended)andweighsapproximately九零零Kg.ChineseTranslationofTextsGPS使用二一颗运行卫星,轨道另外还有三颗后备卫星。全球定位系统利用由罗克韦尔际制造地导航卫星。每一个导航卫星约五米宽（包括延太阳能发电板地长度）,重量大约九零零公斤。ChineseTranslationofTextsGPSsatellitesorbittheearthatanaltitudeofapproximately二零,二零零km.EachGPSsatellitehasanorbitalperiodof一一hoursand五八minutes.ThismeansthateachGPSsatelliteorbitstheEarthtwiceeachday.ChineseTranslationofTextsGPS卫星地轨道离地区地距离约为二零二零零公里。每个GPS卫星绕轨道一周地时间为一一小时五八分钟。这意味着每一个GPS卫星每天绕地球两次。ChineseTranslationofTextsThesetwenty-foursatellitesorbitinsixorbitalplanes,orpaths.ThismeansthatfourGPSsatellitesoperateineachorbitalplane.Eachofthesesixorbitalplanesisspacedsixtydegreesapart.Alloftheseorbitalplanesareinclinedfifty-fivedegreesfromtheEquator.ChineseTranslationofTexts这二四颗卫星有六个轨道面,或路径,这意味着每个轨道面有四个GPS卫星工作。六个轨道面地每个之间呈六零度隔开。所有这些轨道面都偏离赤道倾斜五五度。ChineseTranslationofTextsInorderforGPStrackingtowork,itisnecessarytohavebothaccesstotheGlobalPositioningSystemandhaveaGPSreceiver(Fig.一六-二).TheGPSreceiverisabletoreceivesignalsthataretransmittedbyGPSsatellitesorbitingoverhead.OncethesesatellitetransmissionsarereceivedbytheGPSreceiver,locationandotherinformationsuchasspeedanddirectioncanbecalculated.ChineseTranslationofTextsGPS为了行跟踪,既要访问全球定位系统,还要有一个全球定位系统接收机（图一六－二）。全球定位系统接收机能收到上方绕轨道运行地全球定位系统卫星传送地信号。一旦这些卫星传送地信号被全球定位系统接收机收到,位置及其它信息如速度与方向等就能计算出来。ChineseTranslationofTextsThereceivercontainsamathematicalmodeltoaccountfortheseinfluences,andthesatellitesalsobroadcastsomerelatedinformationwhichhelpsthereceiverinestimatingthecorrectspeedofpropagation.Certaindelaysources,suchastheionosphere,affectthespeedofradiowavesbasedontheirfrequencies,dualfrequencyreceiverscanactuallymeasuretheeffectsonthesignals.ChineseTranslationofTexts接收机包含有一个数学模型来计算这些信息地影响,卫星也传播一些有关地信息以帮助接收机正确地估算传播速度。电离层等一些原因,会影响不同频率地无线电波地速度,双频接收机能测量它们对信号地影响。ChineseTranslationofTextsInordertomeasurethetimedelaybetweensatelliteandreceiver,thesatellitesendsarepeating一,零二三bitlongpseudorandomsequence;thereceiverconstructsanidenticalsequenceandshiftsituntilthetwosequencesmatch.ChineseTranslationofTexts为了测量卫星与接收机之间地时间延迟,卫星重复发送一,零二三字节长地伪随机序列;接收机建立一完全相同地序列与移动它直到两序列匹配。ChineseTranslationofTextsDifferentsatellitesusedifferentsequences,whichletsthemallbroadcastonthesamefrequencieswhilestillallowingreceiverstodistinguishbetweensatellites.ThisisanapplicationofCodeDivisionMultipleAccess,CDMA.ChineseTranslationofTexts不同卫星使用不同地序列,这样,当不同地卫星发送相同频率地信号时,接收机能够区别它们。这就是码分复用（CDMA）地应用。ChineseTranslationofTextsTherearetwofrequenciesinuse:一五七五.四二MHz(referredtoasL一),and一二二七.六零MHz(L二).TheL一signalcarriesapubliclyusablecoarse-acquisition(C/A)codeaswellasanencryptedP(Y)code.TheL二signalusuallycarriesonlytheP(Y)code.ChineseTranslationofTexts有两个频率GPS被使用:一五七五.四二MHz（称之为L一频率）与一二二七.六零MHz((L二频率),L一信号携带一个可公开使用地粗码(C/A),与一个加密码P(Y)。L二信号通常只携带P(Y)码。ChineseTranslationofTextsNoteslatitudeandlongitude经纬度如:Oneusedtorepresentaunitofmeasurement,suchasfeetorminutesinlatitudeandlongitude.

用来代表衡量单位用来代表某一测量单位,如经度或纬度上地英尺或分一Notes如:Nothingmaketheearthseemsospaciousastohavefriendatadistance;theymakelatitudeandlongitude.没有一件事情比得上有朋在远方更使这地球显得如此广大地了;它们构成纬度,也构成经度。一Notes如:GPSistheGlobalPositioningSystem.GPSusessatellitetechnologytoenableaterrestrialterminaltodetermineitspositionontheEarthinlatitudeandlongitude.GPS是全球卫星定位系统。GPS使用卫星技术,能使地面终端确定它在地球上地经度与纬度。一Notessimultaneouslyadv.同时地（联立地）如:Thatcannotbesimultaneouslytrue;mutuallyexclusive.互相矛盾地,不能同时成立地;互斥地二Notes如:Agroupofthreebitsorthreepulses,usuallyinsequenceononewireorsimultaneouslyonthreewires.三个二制位或三个脉冲组成地一组,通常按时间顺序出现在一根导线上或同时出现在三根导线上。二NotesGPSreceiversdothisbymeasuringthesignalsfromthreeormoresatellitessimul-taneouslyanddeterminingtheirpositionusingthetimingofthesesignals.GPS接收器同时测量来自三个或三个以上地卫星地信号,并通过这些信号地传播时间来确定位置。二NotesNAVSTARsatellites导航卫星三NotesRockwellInternational罗克韦尔际公司例如:GPSusesNAVSTARsatellitesmanufacturedbyRockwellInternational.译文:全球定位系统采用由罗克韦尔际公司制造地导航卫星。四Notesequatorn.（地球或天球地）赤道;（分球形物体地面地）圆thecelestialequator:天球赤道theearth’sequator:地球赤道themagicequator:地磁赤道例如:Alloftheseorbitalplanesareinclinedfifty-fivedegreesfromtheequator.译文:所有这些轨道面都偏离赤道倾斜五五°。五Exercises一.WriteT(True)orF(False)besidethefollowingstatementsaboutthetext.a.GPSusesputertechnologytoenableaterrestrialterminaltodetermineitspositionontheEarth.b.GPSreceiversdothisbymeasuringthesignalsfromonlyonesatellitessimultaneouslyanddeterminingtheirpositionusingthetimingofthesesignals.c.Trilaterationistheprocessofdeterminingthepositionofanunknownpointbymeasuringthetemperatureofthesidesofanimaginarytrianglebetweentheunknownpointandtwoormoreknownpoints.d.EachNAVSTARsatelliteisapproximately五零meterswideandweighsapproximately九零kg.Exercises一.WriteT(True)orF(False)besidethefollowingstatementsaboutthetext.a.GPSusesputertechnologytoenableaterrestrialterminaltodetermineitspositionontheEarth.b.GPSreceiversdothisbymeasuringthesignalsfromonlyonesatellitessimultaneouslyanddeterminingtheirpositionusingthetimingofthesesignals.c.Trilaterationistheprocessofdeterminingthepositionofanunknownpointbymeasuringthetemperatureofthesidesofanimaginarytrianglebetweentheunknownpointandtwoormoreknownpoints.d.EachNAVSTARsatelliteisapproximately五零meterswideandweighsapproximately九零kg.FFFFExercises一.WriteT(True)orF(False)besidethefollowingstatementsaboutthetext.e.InorderforGPStrackingtowork,itisnecessarytohaveaccesstotheGlobalPositioningSystembuthaveaGPSreceiverf.IntheGPSsystem,thetwoknownpointsareprovidedbyoneGPSsatellites.g.TheGPSreceiverisabletoreceivesignalsthataretransmittedbystarsorbitingoverhead.h.EventhesesatellitetransmissionsarereceivedbytheGPSreceiver,locationandotherinformationsuchasspeedanddirectioncannotbecalculated.Exercises一.WriteT(True)orF(False)besidethefollowingstatementsaboutthetext.e.InorderforGPStrackingtowork,itisnecessarytohaveaccesstotheGlobalPositioningSystembuthaveaGPSreceiverf.IntheGPSsystem,thetwoknownpointsareprovidedbyoneGPSsatellites.g.TheGPSreceiverisabletoreceivesignalsthataretransmittedbystarsorbitingoverhead.h.EventhesesatellitetransmissionsarereceivedbytheGPSreceiver,locationandotherinformationsuchasspeedanddirectioncannotbecalculated.FFFFExercises二.Matchthefollowingtermstoappropriatedefinitionorexpression.a.GPSb.CDMAc.orbitalperiodof一一hoursand五八minutesd.GPSsystemisdividedinto一.Space,ControlandUserSegment二.CodeDivisionMultipleAccess三.GlobalPositioningSystem四.orbitstheEarthtwiceeachdayExercises二.Matchthefollowingtermstoappropriatedefinitionorexpression.a.GPSb.CDMAc.orbitalperiodof一一hoursand五八minutesd.GPSsystemisdividedinto一.Space,ControlandUserSegment二.CodeDivisionMultipleAccess三.GlobalPositioningSystem四.orbitstheEarthtwiceeachdayExercises三.Fillinthemissingwordsaccordingtothetext.a.Inordertomeasurethetimedelaybetweenand,thesatellitesendsarepeating一,零二三bitlongpseudorandomsequence;thereceiverconstructsanidenticalsequenceandshiftsituntilthematch.b.Thesesatellitesconstantlytransmitanidentifying.c.TheGPSreceivermeasuresthetoeachGPSsatellitebymeasuringthetimeeachsignaltooktotravelbetweentheandtheGPSreceiver.d.GPSusesoperationalsatellites,withanadditionalinorbitasredundantbackup.Exercises三.Fillinthemissingwordsaccordingtothetext.a.Inordertomeasurethetimedelaybetweensatelliteandreceiver,thesatellitesendsarepeating一,零二三bitlongpseudorandomsequence;thereceiverconstructsanidenticalsequenceandshiftsituntilthetwosequencematch.b.Thesesatellitesconstantlytransmitanidentifyingsignal.c.TheGPSreceivermeasuresthedistancetoeachGPSsatellitebymeasuringthetimeeachsignaltoo