GPS全球定位系统及其应用系统技术介绍.docx

GPS全球定位系统及其应用系统技术介绍目录1.前言12 .太空段23 .控制段94 .控制段现代化101. 1.持续升级114. 2.过去的升级115 .下一代操作控制系统146 .民用信号286.1.第二个民用信号：L2C296.2.第三民用信号：L5296.3.第四个民用信号：LlC306.4.无代码/半无代码过渡计划307.民用导航(CNAV)消息431 .前言全球定位系统(GPS)是一家美国拥有的公用事业公司，为用户提供定位、导航和计时(PNT)服务。该系统由三个段组成：空间段、控制段和用户段。美国太空部队开发、维护和运营太空和控制部门。GPS空间部分由向用户发送无线电信号的卫星星座组成。美国致力于在24%的时间内保持至少95颗可运行的GPS卫星的可用性。为了确保这一承诺，美国太空部队十多年来一直在飞行31颗可操作的GPS卫星。surplussatellitesthatexistonorbitwilloupyotherlocationsintheorbitalplanes.Therearenoapriorispecifiedslotsforsurplussatellites.Thenominalsemi-majoraxisis26,559.7kilometers.TheSPSSISgenerationandtransmissionprocessforaBlockIIAsatelliteisillustratedinFigure1.6-1.TheAtomicFrequencyStandard(AFS)generatesanominal10.23MHzclocksignal.ThesignalisdistributedbytheFrequencySynthesizerandDistributionUnit(FSDU)tootherpayloadsubsystems.TheNavigationDataUnit(NDU)receivestheuploadednavigation(NAV)datafromtheControlSegment(CS)throughtheTelemetry,Track,andCommand(TT&C)subsystem.TheNavigationBasebandgeneratesthepseudorandomnoise(PRN)rangingcodesandaddstheNAVFigure1.6-1.GPSSISGenerationandTransmission2 .太空段GPS卫星在大约20,200公里（12,550英里）的高度的中地球轨道（MEO）飞行。每颗卫星每天绕地球两圈。GPS星座中的卫星排列成围绕地球的六个等间距轨道平面。每个平面包含四个由基线卫星占用的“插槽”。这种24插槽布置确保用户可以从地球上的几乎任何一点查看至少四颗卫星。太空部队通常飞行超过24颗GPS卫星，以便在基线卫星维修或退役时保持覆盖。额外的卫星可能会提高GPS性能，但不被视为核心星座的一部分。1.6.2GPSControlSegmentTheOperationalControlSystem(OCS)iscomprisedoffourmajorsubsystems:aMasterControStation(MCS1soontobereplacedbyaNewMasterControlStationNMCS),aBackupMasterControlStation(BMCS,sntobereplacedbyanAlternateMasterControlStationAMCS),anetworkoffourgroundantennas(GAs)1andanetworkofglobally-distributedmonitorstations(MSs).AnoverviewoftheOCSisprovidedinFigure1.6-2.Figure 1.6-2. The GPS Operational Control System (OCS)Performance Assess FunctionSatellite Control Function Command Generation Telemetry Processing Upload Generation & Control Check performance against specificationsif failure detectedPositioning&TimingFunction RangingMeasurementProcessing SatelliteStateEstimatiofVPredictjonDataGeneration2011年4月，美国空军成功完成了被称为“可扩展24”配置的GPS星座扩展。27个插槽中的三个被扩展，六颗卫星被重新定位，因此其中三颗额外的卫星成为星座基线的一部分。因此，GPS现在有效地作为星座运行，在世界大部分地区的覆盖范围有所改善。RAIMrequiresafifthsatellite,orbarometricaiding,toperformansistencychecktodetectafaultonasinglesatellite.TheGPSWAASreceivercompliantwithTSO-C145/146alsousesRAIMforinstanceswhentheaugmentationsignalbecomesunavailable.TheWAASreceiveraddsafaultdetection&exclusion(FDE)featurerequiringaminimumof6satellitestodetectandexcludeafaultedsatellite.InsteadofdeclaringGPSSPSserviceunusablewithaRAIMalert,RAIM/FDEexcludesthebadsatelliteandcontinuestoprovideanintegrity-assuredsolutionprovidedthegeometryoftheremainingsatellitesinviewissufficient.TheWAASGEObroadcastalsoprovidesanadditionalrangingsourceforimprovedavailabilityofnavigationservices.WhenaWAASreceiverisusingtherrectionsandintegritymessagesbroadcastbytheGEO,onlyfourGPSorGEOsatellitesareneeded,whichincreasestheavailabilityofserviceversusRAIMorRAIM/FDE.WAAScalculatesintegritydataassociatedwithitsgeneratedcorrectionsattherequiredlevelofintegrityfortheintendedflightoperation.Integritydataisprovidedintheformoferrorboundswhichareusedtocomputetheprotectionlevelstakingallrelevanterrorsourcesintoaccount.TheintegritydataconsistsoftheUserDifferentialRangeError(UDRE)andtheGridIonosphericVerticalError(GIVE).UDREcharacterizestheresidualerrorintheFCandLTC.TheUDREistransmittedwiththeFCmessage.GIVEcharacterizestheresidualerrorintheICfortheestimatedionospheresignaldelayscalculatedforIGPs,definedintheIGPmaskandbroadcastevery5minutes.TheGIVEistransmittedwiththeICmessage.IfusingWAASverticalguidance,theuserreceiverutilizesthisintegritydatatocalculatea"protectioncylinder"asdefinedintheRTCAInc.(formerlyRadioTechnicalCommissionforAeronautics)MinimumOperationalPerformanceStandard(MOPS)(RTCA/DO-229),incorporatedbyreference,inTSO-C145146.AsimplifieddepictionisshowninFigure1.7-2.TheuserreceiverappliesthevariousWAASrectionsdescribedaboveandcalculatesauserpositionusingtheWAAScorrectedrangeandephemerisdata.Then,theuserreceiverappliestheUDRE,GIVE(andothererrorcharacteristicsforresidualtropospheredelayandreceivererrors)valuestocalculateVPLandHPL.Theseprotectionlimitscanbeenvisionedasdefiningaprotectioncylinder,depictedasthedarkcylinderinFigure1.7-2.VerticalandHorizontalAlertLimitCylindCrarcdefinedbythephaseofflightProtection level cylinder: VPL and HPL are computed by the user's receiver from error bounds calculated by WAAS (UDRE and GIVE).Theaircraft'scalculatedpositionbasedontheWAAScorrectionsisthecenterofthecylinder.Theaircraft'struepositionFigure1.7-2WAASIntegrityProtectionCylinderThisprotectioncylinder,centeredontheuser'scalculatedpositionoftheaircraft,representstheuncertaintyofthatcalculatedposition.Theuser'sreceivercalculatesandcomparestheVPLandHPLagainsttheVerticalAlertLimit(VAL)andHorizontalalertLimit(HAL)values,respectively.ThesealertlimitshavevaluesthatarefixedforeachflightoperationandcanbethoughtofasdefiningtheclearalertlimitcylinderinFigure1.7-2.Thealertlimitcylinderiscenteredontheaircraft,sWAAScalculatedposition,justastheprotectionlevelcylinder.Normally,theaircraft'struepositioniswithinthedarkprotectionlevelcylinder.IftheWAASintegritydataresultsinaprotectionlevelcylinderthatistoolargetobecontainedwithinthealertlimitcylinderforaparticularflightoperation,theuserreceiverwillindicatetothepilotthattheoperationisnotavailable.Forexample,ifthealertlimitforLPVisexceeded,thereceiverwillnotifythepilotthatLPVisnolongeravailable.ItislikelyinthisscenariothattheLateralNavigation(LNAV)alertlimit,whichismuchlarger,willnotbeexceededandthereforethereceiverindicationofLNAVoperationwouldstillbeavailable.HazardouslyMisleadingInformation(HMI)existswhentheuser,spositionerrorexceedstheprotectionlevelsforaperiodlongerthanthetime-to-alert(TTA).Iftheprotectioncylinderistoosmall,itwillnotenclosetheaircraft'strueposition.Thisisanunderboundndition.WhentheunderboundnditionpersistsforlongerthantheTTA,thiseventisthe洌f77掰underboundnditioncannotbedetectedbythereceiversotheWAASintegrityAlgorithmsareGPS星座是新旧卫星的混合体。下表总结了当前和未来几代全球定位系统卫星的特点，包括第二组(第二代，“高级”)、第二组(“补给”)、第二层M(“现代化”)、第二组(“后续”)、第三类和第三国际定位系统(“后续”)。O67126操作操作操作操作操作- 所有块IIF信号- L4 (L1C)上的第1个民用 号了解更多，- 增强信号的可靠性. 确性和完整性- 无选择性可用性 了解更多，- 15年设计寿命- IIIF:激光反射器对 和救援有效载荷- 面向民用用户的Ll频率上的粗略采集(C/A)代码- 为军事用户提供LI和L2频率上的精确P(Y)码- 7.5年设计寿命- 1990-1997年推出- 最后一个在2019年退役- 1.1上的C/A代码- 1.I和L2上的P(Y)代码- 板载时钟监控- 7.5年设计寿命- 19972004年推出- 所有遗留信号- 1.2(L2C)上的第二个民用信号了解更多- 新的军用M代码信号增强了抗卡纸性- 灵活的军事信号功率水平- 7.5年设计寿命- 20052009年推出所有BlockIIR-M信号1.3癖(L5)上的第5个民用信号了解更多，先进的原子钟提高精度、信号强度和质量12年设计寿命20102016年推出TheGPSWAASarchitectureandoperationalenvironmentareshowninFigure1.7-3.ThespacesegmentconsistsoftheGPSandGEOsatellites.TheGPSnstellationnominallynsistsof24satelliteslocatedinorbitalslotsdistributedin6differentorbitalplanes(anaverageofapproximately8-10satellitesareinviewtoauseratanytime).TheGPSSPSPSntainsampletedescriptionoftheGPSconstellation.EachGPSsatellitetransmitssignalsontwofrequenciesthatareusedbyWAAS.TheLink1(GPSL1)1575.42MHzCoarseAcquisition(CA)codedsignalcontainstheorbitalandtimingparametersthatareceiverrequirestocalculatetheuser'sposition.TheL2signalisthe1227.60MHzP(Y)codedsignal.Currently,theWAASuserreceiverreceivesonlytheL1signal.Figure1.7-3WAASArchitectureandOperationalEnvironmentFigure 1.7-4 shows the WAAS data processing path. WAAS receives the GPS satellite signals and processes the GPS satellite data to determine the corrections and integrity data for each satellite. The resultant correction and integrity data for each GPS satellite is referred to as the WAAS message. The WAAS message is uplinked to the GEO satellites for broadcast on the GPS L1 frequency. The user receives the signal with a unique GEO satellite pseudo-random noise (PRN) number coding on the SIS. The user receiver extracts the various corrections and integrity data for the GPS and GEO satellites to calculate an accurate position and associated protection level(s). WAAS also controls the timing of the GEO satellite signal and generates the GEO satellite navigation message data (GEO satellite position and clock) that enables use of the GEO satellites as an additional GPS-Iike ranging source.GreenUndSouth KoraC«p« CAnaveral orid* Bahrain UrufuayX Alternate Master Control Station . AFSCN Remote Tracking Station NGAMonitor StationUnited KingdomSChrieVr AFB Co4or.do “. a re 一 New Himpibire "F器然人 * USN0Wwh1nft0HGuam Kw*jletnAustralia Z>l>ndMasterControlStationGroundAntennaAirForceMonitorStation3.控制段GPS控制部分由全球地面设施网络组成，这些设施跟踪GPS卫星，监控其传输，执行分析并向星座发送命令和数据。目前的操作控制段(OCS)包括一个主控制站，一个备用主控制站，11个指挥和控制天线以及16个监控站点。GPS星座提供了始终如一的高性能，这要归功于其运营商的不懈努力美国空军第2太空作战中队(2S0PS)和位于科罗拉多州施里弗太空部队基地的空军预备役第19太空作战中队(19S0PS)的男女。2S0PS和19SOPS(绰号"二十一点团队”)共同保持GPS卫星24/7全天候飞行，为数十亿民用和军用用户提供持续可用性和高精度。2008年完成的“传统精度改进计划”将全球定位系统业务控制部分的监测站数量从6个增加到10个。这使在GPS卫星轨道上收集的数据量增加了两倍，使GPS星座广播信息的准确性提高了15%至20%。1.-An的努力增加了10个由国家地理空间情报局(NGA)拥有和运营的GPS监测站。NGA最初部署这些站点是为了帮助它定义GPS使用的地球参考框架.控制段耗监控站跟踪GPS卫星经过头顶主控站-提供GPS星座的命令和控制地面天线-向卫星发送命令、导航数据上 传和处理器程序加载- 收集导航信号、距离/载波测 量值和大气数据- 将观测结果馈送到主控制站- 利用先进的GPS接收器- 通过16个站点提供全球覆 盖：6个来自空军，10个来自NGA，- 使用全球监测站数据计算卫星 的精确位置- 生成导航消息以上传到卫星- 监控卫星广播和系统完整性， 以确保星座的健康和准确性- 执行卫星维护和异常解决，包 括重新定位卫星以保持最圭星 座- 目前使用单独的系统(AEP， 和LADC) 来控制运行和非 运行卫星- 由完全可操作的备用主控制站 提供支持- 收集遥测数据- 通过S波段进行通信并执行S 波段测距，以提供异常分辨率 和早期轨道支持- 由4个专用GPS地面天线和7 个空军卫星控制网络(AFSCN)远程跟踪站组成4.控制段现代化作为GPS现代化计划的一部分,空军多年来不断升级GPS控制部分。地面升级对于指挥和控制较新的GPS卫星以及加强网络安全是必要的。4.1. 持续升级OCX：下一代操作控制系统二氧化碳：全球定位系统In应急行动MCEU：M代码早期使用4.2.过去的升级AEP：架构演进计划1.ADO：发射/早期轨道、异常解决和处置操作1.-AII：传统精度改进计划TheportionofthesurfaceoftheEarthwhichisvisiblefromasatellite'sorbitallocationisknownasthesatellites"footprint".SeeFigureA.3-1.Thefootprintofeachsatelliteoccupyingaslotinthebaselinee×pandable24-slotconstellationcoversapproximately38%oftheEarth'ssurface.Theuseofartificialmaskangleswillreducethesatellite'seffectiveftprint.Witha5-degreemaskangle,asatellite'seffectiveftprintisreducedtoslightlymorethanone-thirdoftheEarth'ssurface(33.9%).Thenear-EarthregionextendingfromthesurfaceoftheEarthuptoanaltitudeof3,000kmabovethesurfaceoftheEarthisalsoknownasthe"terrestrialservicevolume*.SeeFigureA.3-2.统宓二斤流FigureA.3-2.IllustrationofTerrestrialServiceVolumeFigure A.4-1. UERE Graceful DegradationWhenthesatellitesarebeinguploadedonaroutinebasis,theSPSSISaccuracystandardswhichapplyareforthenormaloperationsmode.Duringnormaloperations,eachsatelliteintheconstellationisuploadedatleastonceperday.Additional(ntingency)uploadsmaybenecessaryforcertainsatellitesasdescribedinthefollowingsection.Thenormaloperationsmodeisshownatthefarleft-handsideofFigureA.4-1.TheSPSSISindicateswhenthesatelliteisinthenormaloperationsmodebywayoftheCA-designalLNAVdatastreamfitintervalflags-9E-%g6)山HWnQllllllllllll.O2468101214161820222426AgeofData(AOD),hoursNottoscaleFigureA.4-2a.UEREasaFunctionofAOD,One-Upload-Per-DayScenarioAge of Data (AOD), hoursNo*统立才而FigureA.4-2b.UEREasaFunctionofA0D,Three-Uploads-Per-DayScenarioFigureA.4-3.StatisticalSPSSISUREasaFunctionofAOD,One-Upload-Per-DayScenarioUploadUploadUploadnoeu2u2s)山Hn20/ > Time,24 hoursNottoscaleFigureA.4-4.InstantaneousSPSSISUREasaFunctionofTimeNote:1. TheinstantaneousUREcanbepositiveornegativeasshowninFigureA.4-4.ThestatisticalUREisalwaysunsigned(illustratedaspositive)asshowninFiguresA.4-1throughA.4-3.InFigureA.4-4,theuploadsareshownasourringatapproximately00:42,08:28,16:29,and23:57.EachuploadischaracterizedbytheinstantaneousSPSSISUREresettingtonearzeroasaresultofthesatellitestartingtobroadcastthefreshNAVmessagewhichhasjustbeenuploaded.ThetransitionfromthestaleoldNAVmessagedatatothefreshnewNAVmessagedataisknownasan"uploadcutover*.Inadditiontothelargediscontinui'手痂cutovers,FigureA.4-4alsoshowsmuchsmallerdiscontinuitiesoccurring-atthe2-hour5.下一代操作控制系统下一代操作控制系统(OCX)是GPS控制领域的未来版本。OCX将指挥所有现代化和传统GPS卫星，管理所有民用和军用导航信号，并为下一代GPS操作提供改进的网络安全和弹性。它将包括：1）主控制站和备用主控制站2）专用监测站3）地面天线4）GPS系统模拟器和5）标准化的空间训练器。6）0CX开发遵循渐进式方法。BIOCko是发射和控制系统（LCS）,旨在控制发射和早期轨道（LEO）操作以及所有GPSIn卫星的在轨检查。OCXBIOCkO是OCXBk）Ckl的子集，为Block1提供硬件、软件和网络安全基础。第1组涉及控制所有遗留卫星和民用信号（LlC/A）、军事信号（LlP（Y）、L2P（Y）以及GPSln卫星和现代化民用信号（L2C）和航空飞行安全信号（L5）的操作能力。此外，Block1将具备控制现代化军事信号（LlM和L2M（M代码）和全球兼容信号（LlC）的基本作战能力。它还完全满足信息保障/网络防御要求。BIOCk2提供先进的作战能力，以控制现代化军事信号（LlM和L2M（M代码）的高级功能。区块2将与区块1同时交付。BIOCk3F将升级OCX,使其具有与GPSnIF空间段和军事GPS用户设备（MGUE）增量2功能同步的新功能。OCXBlock3F需要发射和操作指挥和控制GPSIIIF太空飞行器。thereisasignificantamountofoverlapbetweenthecivilmonitoringrequirementsandthoseofgeneralinterest.ThisisillustratedinFigure1-1.Figure1-1-PartitioningofMonitoringRequirementsThispartitioningofrequirementsmayhavepracticalimplications.Inthecurrent"U.S.Space-BasedPositioning,Navigation,andTimingPolicy,itisnotedthat".civilsignalperformancemonitoring.willhefundedbytheagencyoragenciesrequiringthoseservicesorcapabilities,includingout-yearprocurementandoperationscostsTherefore,fundingforthedevelopmentandoperationofmonitoringcapabilitiesmayfallunderthejurisdictionofdifferentorganizationsdependingonwhethertherequirementisrelatedtoaparticularusercommunit-r统兜把桢tobeofgeneralimportance.s,107eulUJHn Sno8usussNottoscaleFigure A.4-5b. Instantaneous PPS SIS URRE as a Function of Time3esE c山Ban SnoeUPHleJSU-Figure A.4-5c. Instantaneous PPS SIS URRRE as a Function Ofm?系统技才交流oesZoesZEurHan soc2c2c-FigureA.4-5a.InstantaneousPPSSISUREasaFunctionofTimeAsdescribedearlierinthisSection,theGPSUEREbudgetsandthePPSSISaccuracystandardsvaryasafunctionoftheparticularPPSSIScomponentsandasafunctionoftheelapsedtimesinceupload.TheUEREbudgetsandSISaccuracystandardsdonotvaryasafunctionofthespatialuIookangles"relativetotheNavstarsatellites.TheUEREbudgetsandaccuracystandardsapplyequallyateverypointwithinthesatellite'scoveragefootprint.Inreality,however,thePPSSISUREdoesvarysignificantlyacrosseachsatellite'scoverage.Thesourceofthisspatialdependencyareerrorsinthesatelliteorbit.Satelliteorbiterrorsareprimarilyduetoeither:(a)unpredictablesatelliteaccelerations,or(b)inaccurateephemerisdatauploads.ThedistinctionbetweenthesesourcesofsatelliteorbiterrorsismanifestedintheUEREbudgetsofTablesA.4-1throughA.4-4.Unpredictablesatelliteaccelerationsaresatellitespecific,andtheSpaceSegmenthasaUEREbudgetallocationfortheminTablesA.4-1throughA.4-4.Inaccurateephemerisdatauploadsareduetoamixofestimation/predictionerrorspluscurvefitlimitations,andtheControlSegmenthasUEREbudgetallocationsforeachoftheminTablesA.4-1throughA.4-4.Therearealsosecondarycausesofsatelliteorbiterrors,suchasmis-orietationoftheleverarmfromthesatellitecenterofmasstothebroadcastantennaphasecenter.ThesesecondarycausesofsatelliteorbiterrorsarealsointheUEREbudgetsofTablesA.4-1throughA.4-4undertheuothersegmenterrors'1linesfortheS