《智能传感器装调与测试（双语）》课件-25.GNSS 信号遮挡场景

GNSS信号遮挡场景GlobalNavigationSatelliteSystem(GNSS)SignalBlockingScenarios视频1Video1视频2Video2PART01GNSS工作的核心原理和两大前提CorePrincipleandTwoMajorPremisesofGNSSGNSS工作的核心原理CorePrincipleofGNSS智能车的GNSS接收机需同时接收至少4颗卫星的信号，通过测量信号传播时间（TOA）计算车辆与卫星的距离，再结合卫星的精确轨道位置，最终解算出车辆的三维坐标（经度、纬度、高程）。TheGNSSreceiverofanintelligentvehicleneedstoreceivesignalsfromatleast4satellitesatthesametime,calculatethedistancebetweenthevehicleandthesatellitesbymeasuringtheTimeofArrival(TOA),andthencombinetheresultswiththepreciseorbitalpositionsofthesatellitestofinallysolvethethree-dimensionalcoordinates(longitude,latitude,andelevation)ofthevehicle.GNSS接收卫星信号GNSSreceivessatellitesignalsGNSS定位必须满足的两大前提TwoMajorPremisesofGNSS前提一：信号传播路径相对直接，避免异常延迟；前提二：接收机能清晰识别信号特征，区分有效星与干扰；遮挡场景同时破坏这两条，导致定位失效。Premise1:Thesignalpropagationpathisrelativelydirecttoavoidabnormaldelays.Premise2:Thereceivercanclearlyidentifythesignalcharacteristicsanddistinguishbetweeneffectivesignalsandinterferencesignals.Ifthetwopremisesarenotmetinablockingscenario,positioningwillfail.GNSS定位基本框架BasicframeworkofGNSSpositioning-两大前提-TwomajorpremisesPART02隧道阶段性失效链PhasedFailureChaininTunnels进隧道前多径诱发信号受阻BlockingofMultipathInducedSignalsBeforeTheyEntertheTunnel直射波受阻：导航信号（如GPS）需穿透隧道墙体和顶部结构，但混凝土、金属等材料会显著吸收或反射信号，导致强度减弱。Blockingofthedirectwave:Navigationsignals(suchasGPSsignals)needtopenetratethetunnelwallandtopstructure,butmaterialssuchasconcreteandmetalwillsignificantlyabsorborreflectthesignals,weakeningtheirstrength.反射波干扰：隧道入口的封闭环境限制了反射波的传播路径，信号接收质量下降。Interferencewiththereflectedwave:Theclosedenvironmentatthetunnelentrancelimitsthepropagationpathofthereflectedwave,andthesignalreceptionqualityisreduced.-GNSS在隧道内信号受阻-GNSSsignalsareblockedintunnels进隧道前多径诱发信号受阻BlockingofMultipathInducedSignalsBeforeTheyEntertheTunnel多径效应：信号在隧道口可能被墙体、地面等多次反射，导致接收设备接收到多个延迟的信号副本，引发伪距计算偏差。Multipatheffect:Thesignalmaybereflectedmultipletimesbythewallsandthegroundatthetunnelentrance.Asaresult,thereceiverreceivesmultipledelayedsignalcopies,resultinginpseudo-rangecalculationdeviation.精度下降‌：部分信号被遮挡后，设备依赖的卫星信号数量减少，定位精度降低，进一步放大误差

。Decreasedprecision:Aftersomesignalsareblocked,thenumberofsatellitesignalsthatthedevicereliesondecreases,thepositioningprecisiondeclines,andtheerrorisfurtheramplified.-GNSS在隧道内信号受阻-GNSSsignalsareblockedintunnels隧道内信号中断与冻结漂移SignalInterruption,Freezing,andDriftinTunnels隧道内GNSS信号中断

GNSSsignalinterruptionintunnels卫星归零Satellitezeroing全封闭段卫星数归零，无法满足≥4颗定位星座，系统被迫冻结在洞口最后有效坐标。Thenumberofsatellitesinthefullyenclosedsectionreturnstozero,whichcannotmeettherequirementfor4ormorepositioningconstellations.Thesystemisforcedtofreezeatthelastvalidcoordinatesatthetunnelentrance.惯性推算Inertialcalculation若继续惯性推算，每10秒横向累积5–10m误差，一公里隧道可超百米偏移。Iftheinertialcalculationcontinues,thelateralerroraccumulatesby5–10metersevery10seconds,andthedeviationcanexceed100metersinatunnelofonekilometer.表现差异Performancedifference冻结坐标与惯性漂移两种表现，均导致定位丢失，为后续跳变埋下伏笔。Bothfrozencoordinatesandinertialdriftleadtolossofpositioning,layingthegroundworkforsubsequentjumps.出隧道跳变与二次多径风险TunnelJumpandSecondaryMultipathRisks捕获延迟Capturedelays决策误判

Decision-makingmisjudgment驶出隧道时卫星重新捕获需1–3s，期间出口强光与结构产生二次多径，定位点从漂移坐标瞬间跳回真实位置，跳变量10–30m。Ittakes1–3secondstoreacquirethesatellitesignalafterthevehicleleavesthetunnel.Duringthisperiod,thestronglightattheexitandthestructuregeneratesecondarymultipath,andthepositioningpointjumpsbacktothetruepositioninstantlyfromthedriftcoordinateswithajumpof10–30meters.该跳变易被决策层误判为车辆急变道，触发不必要的横向控制干预，出口仍是高风险区。Thisjumpiseasilymisjudgedbythedecision-makinglevelasasuddenlanechangeofthevehicle,triggeringunnecessarylateralcontrolintervention.Therefore,theexitisstillahigh-riskarea.PART03高楼峡谷动态波动失效DynamicFluctuationFailureinHigh-RiseCanyons星座残缺与GDOP恶化引发锯齿漂移SawtoothDriftInducedbyConstellationIncompletenessandGeometricDilutionofPrecision(GDOP)Deterioration峡谷环境卫星数随车辆移动在2–8颗间剧烈波动，多为低仰角星，GDOP由2升至10以上，误差从厘米级扩至米级甚至十米级，直线行驶却呈横向锯齿轨迹，系统难辨主辅路，揭示与隧道阶段性失效本质差异。Inacanyonenvironment,thenumberofsatellitesfluctuatesviolentlybetween2and8asthevehiclemoves;mostofthemarelow-elevationsatellites.GDOPrisesfrom2tomorethan10,andtheerrorexpandsfromcentimeterstometersoreventensofmeters.Whenavehicleisdrivinginastraightline,thesignalshowsahorizontalsawtoothtrajectory,whichmakesitdifficultforthesystemtodistinguishthemainandauxiliaryroads.Thisrevealstheessentialdifferencefromthephasedfailureinthetunnel.卫星信号随车辆移动产生波动Satellitesignalsfluctuatewithvehiclemovement-波动型失效-Fluctuationfailure多径效应引发“信号混淆”SignalConfusionInducedbytheMultipathEffect高楼峡谷的多径效应比隧道更复杂，主要有两种类型：一是“镜面反射”，卫星信号经高楼玻璃幕墙、金属广告牌反射后被接收机接收；二是“绕射传播”，信号绕过高楼棱角后发生波形畸变。Themultipatheffectinhigh-risecanyonsismorecomplexthanthatintunnels.Itisdividedintotwomaintypes.Oneismirrorreflection.Satellitesignalsarereflectedbytheglasscurtainwallsandmetalbillboardsofhigh-risebuildingsandreceivedbythereceiver.Theotherisdiffractionpropagation.Waveformdistortionoccursafterthesignalbypassestheedgesandcornersofhigh-risebuildings.信号混淆Signalconfusion动态遮挡导致“定位中断频发”FrequentPositioningInterruptionsInducedbyDynamicBlocking车辆在高楼峡谷中转弯、变道时，会遭遇“瞬时动态遮挡”,中断虽持续时间短，但对自动驾驶影响极大。Whenavehicleturnsorchangeslanesinhigh-risecanyons,itwillencounterinstantaneousdynamicblocking.Althoughtheinterruptionlastsonlyforashorttime,ithasasignificantimpactonautonomousdriving.车辆转弯变道Vehicleturningandlanechange本讲核心理论回顾ReviewofCoreTheoriesinThisLectureGNSS定位依赖“足量卫星+清晰信号”，而隧道与高楼峡谷通过“遮挡”和“多径”破坏了这两个前提。隧道场景呈现“进洞衰减-洞内丢失-出洞跳变”的阶段性失效；高楼峡谷则表现为“星座残缺-信号混淆-动态中断”的动态波动失效。两种场景的失效本质都是“卫星信号传播异常”，但因环境封闭性、遮挡物特性不同，失效模式存在明显差异。GNSS