GNSS信號(hào)遮擋場(chǎng)景GlobalNavigationSatelliteSystem(GNSS)SignalBlockingScenarios視頻1Video1視頻2Video2PART01GNSS工作的核心原理和兩大前提CorePrincipleandTwoMajorPremisesofGNSSGNSS工作的核心原理CorePrincipleofGNSS智能車的GNSS接收機(jī)需同時(shí)接收至少4顆衛(wèi)星的信號(hào)，通過測(cè)量信號(hào)傳播時(shí)間（TOA）計(jì)算車輛與衛(wèi)星的距離，再結(jié)合衛(wèi)星的精確軌道位置，最終解算出車輛的三維坐標(biāo)（經(jīng)度、緯度、高程）。TheGNSSreceiverofanintelligentvehicleneedstoreceivesignalsfromatleast4satellitesatthesametime,calculatethedistancebetweenthevehicleandthesatellitesbymeasuringtheTimeofArrival(TOA),andthencombinetheresultswiththepreciseorbitalpositionsofthesatellitestofinallysolvethethree-dimensionalcoordinates(longitude,latitude,andelevation)ofthevehicle.GNSS接收衛(wèi)星信號(hào)GNSSreceivessatellitesignalsGNSS定位必須滿足的兩大前提TwoMajorPremisesofGNSS前提一：信號(hào)傳播路徑相對(duì)直接，避免異常延遲；前提二：接收機(jī)能清晰識(shí)別信號(hào)特征，區(qū)分有效星與干擾；遮擋場(chǎng)景同時(shí)破壞這兩條，導(dǎo)致定位失效。Premise1:Thesignalpropagationpathisrelativelydirecttoavoidabnormaldelays.Premise2:Thereceivercanclearlyidentifythesignalcharacteristicsanddistinguishbetweeneffectivesignalsandinterferencesignals.Ifthetwopremisesarenotmetinablockingscenario,positioningwillfail.GNSS定位基本框架BasicframeworkofGNSSpositioning-兩大前提-TwomajorpremisesPART02隧道階段性失效鏈PhasedFailureChaininTunnels進(jìn)隧道前多徑誘發(fā)信號(hào)受阻BlockingofMultipathInducedSignalsBeforeTheyEntertheTunnel直射波受阻：導(dǎo)航信號(hào)（如GPS）需穿透隧道墻體和頂部結(jié)構(gòu)，但混凝土、金屬等材料會(huì)顯著吸收或反射信號(hào)，導(dǎo)致強(qiáng)度減弱。Blockingofthedirectwave:Navigationsignals(suchasGPSsignals)needtopenetratethetunnelwallandtopstructure,butmaterialssuchasconcreteandmetalwillsignificantlyabsorborreflectthesignals,weakeningtheirstrength.反射波干擾：隧道入口的封閉環(huán)境限制了反射波的傳播路徑，信號(hào)接收質(zhì)量下降。Interferencewiththereflectedwave:Theclosedenvironmentatthetunnelentrancelimitsthepropagationpathofthereflectedwave,andthesignalreceptionqualityisreduced.-GNSS在隧道內(nèi)信號(hào)受阻-GNSSsignalsareblockedintunnels進(jìn)隧道前多徑誘發(fā)信號(hào)受阻BlockingofMultipathInducedSignalsBeforeTheyEntertheTunnel多徑效應(yīng)：信號(hào)在隧道口可能被墻體、地面等多次反射，導(dǎo)致接收設(shè)備接收到多個(gè)延遲的信號(hào)副本，引發(fā)偽距計(jì)算偏差。Multipatheffect:Thesignalmaybereflectedmultipletimesbythewallsandthegroundatthetunnelentrance.Asaresult,thereceiverreceivesmultipledelayedsignalcopies,resultinginpseudo-rangecalculationdeviation.精度下降?：部分信號(hào)被遮擋后，設(shè)備依賴的衛(wèi)星信號(hào)數(shù)量減少，定位精度降低，進(jìn)一步放大誤差

。Decreasedprecision:Aftersomesignalsareblocked,thenumberofsatellitesignalsthatthedevicereliesondecreases,thepositioningprecisiondeclines,andtheerrorisfurtheramplified.-GNSS在隧道內(nèi)信號(hào)受阻-GNSSsignalsareblockedintunnels隧道內(nèi)信號(hào)中斷與凍結(jié)漂移SignalInterruption,Freezing,andDriftinTunnels隧道內(nèi)GNSS信號(hào)中斷

GNSSsignalinterruptionintunnels衛(wèi)星歸零Satellitezeroing全封閉段衛(wèi)星數(shù)歸零，無法滿足≥4顆定位星座，系統(tǒng)被迫凍結(jié)在洞口最后有效坐標(biāo)。Thenumberofsatellitesinthefullyenclosedsectionreturnstozero,whichcannotmeettherequirementfor4ormorepositioningconstellations.Thesystemisforcedtofreezeatthelastvalidcoordinatesatthetunnelentrance.慣性推算Inertialcalculation若繼續(xù)慣性推算，每10秒橫向累積5–10m誤差，一公里隧道可超百米偏移。Iftheinertialcalculationcontinues,thelateralerroraccumulatesby5–10metersevery10seconds,andthedeviationcanexceed100metersinatunnelofonekilometer.表現(xiàn)差異Performancedifference凍結(jié)坐標(biāo)與慣性漂移兩種表現(xiàn)，均導(dǎo)致定位丟失，為后續(xù)跳變埋下伏筆。Bothfrozencoordinatesandinertialdriftleadtolossofpositioning,layingthegroundworkforsubsequentjumps.出隧道跳變與二次多徑風(fēng)險(xiǎn)TunnelJumpandSecondaryMultipathRisks捕獲延遲Capturedelays決策誤判

Decision-makingmisjudgment駛出隧道時(shí)衛(wèi)星重新捕獲需1–3s，期間出口強(qiáng)光與結(jié)構(gòu)產(chǎn)生二次多徑，定位點(diǎn)從漂移坐標(biāo)瞬間跳回真實(shí)位置，跳變量10–30m。Ittakes1–3secondstoreacquirethesatellitesignalafterthevehicleleavesthetunnel.Duringthisperiod,thestronglightattheexitandthestructuregeneratesecondarymultipath,andthepositioningpointjumpsbacktothetruepositioninstantlyfromthedriftcoordinateswithajumpof10–30meters.該跳變易被決策層誤判為車輛急變道，觸發(fā)不必要的橫向控制干預(yù)，出口仍是高風(fēng)險(xiǎn)區(qū)。Thisjumpiseasilymisjudgedbythedecision-makinglevelasasuddenlanechangeofthevehicle,triggeringunnecessarylateralcontrolintervention.Therefore,theexitisstillahigh-riskarea.PART03高樓峽谷動(dòng)態(tài)波動(dòng)失效DynamicFluctuationFailureinHigh-RiseCanyons星座殘缺與GDOP惡化引發(fā)鋸齒漂移SawtoothDriftInducedbyConstellationIncompletenessandGeometricDilutionofPrecision(GDOP)Deterioration峽谷環(huán)境衛(wèi)星數(shù)隨車輛移動(dòng)在2–8顆間劇烈波動(dòng)，多為低仰角星，GDOP由2升至10以上，誤差從厘米級(jí)擴(kuò)至米級(jí)甚至十米級(jí)，直線行駛卻呈橫向鋸齒軌跡，系統(tǒng)難辨主輔路，揭示與隧道階段性失效本質(zhì)差異。Inacanyonenvironment,thenumberofsatellitesfluctuatesviolentlybetween2and8asthevehiclemoves;mostofthemarelow-elevationsatellites.GDOPrisesfrom2tomorethan10,andtheerrorexpandsfromcentimeterstometersoreventensofmeters.Whenavehicleisdrivinginastraightline,thesignalshowsahorizontalsawtoothtrajectory,whichmakesitdifficultforthesystemtodistinguishthemainandauxiliaryroads.Thisrevealstheessentialdifferencefromthephasedfailureinthetunnel.衛(wèi)星信號(hào)隨車輛移動(dòng)產(chǎn)生波動(dòng)Satellitesignalsfluctuatewithvehiclemovement-波動(dòng)型失效-Fluctuationfailure多徑效應(yīng)引發(fā)“信號(hào)混淆”SignalConfusionInducedbytheMultipathEffect高樓峽谷的多徑效應(yīng)比隧道更復(fù)雜，主要有兩種類型：一是“鏡面反射”，衛(wèi)星信號(hào)經(jīng)高樓玻璃幕墻、金屬廣告牌反射后被接收機(jī)接收；二是“繞射傳播”，信號(hào)繞過高樓棱角后發(fā)生波形畸變。Themultipatheffectinhigh-risecanyonsismorecomplexthanthatintunnels.Itisdividedintotwomaintypes.Oneismirrorreflection.Satellitesignalsarereflectedbytheglasscurtainwallsandmetalbillboardsofhigh-risebuildingsandreceivedbythereceiver.Theotherisdiffractionpropagation.Waveformdistortionoccursafterthesignalbypassestheedgesandcornersofhigh-risebuildings.信號(hào)混淆Signalconfusion動(dòng)態(tài)遮擋導(dǎo)致“定位中斷頻發(fā)”FrequentPositioningInterruptionsInducedbyDynamicBlocking車輛在高樓峽谷中轉(zhuǎn)彎、變道時(shí)，會(huì)遭遇“瞬時(shí)動(dòng)態(tài)遮擋”,中斷雖持續(xù)時(shí)間短，但對(duì)自動(dòng)駕駛影響極大。Whenavehicleturnsorchangeslanesinhigh-risecanyons,itwillencounterinstantaneousdynamicblocking.Althoughtheinterruptionlastsonlyforashorttime,ithasasignificantimpactonautonomousdriving.車輛轉(zhuǎn)彎變道Vehicleturningandlanechange本講核心理論回顧ReviewofCoreTheoriesinThisLectureGNSS定位依賴“足量衛(wèi)星+清晰信號(hào)”，而隧道與高樓峽谷通過“遮擋”和“多徑”破壞了這兩個(gè)前提。隧道場(chǎng)景呈現(xiàn)“進(jìn)洞衰減-洞內(nèi)丟失-出洞跳變”的階段性失效；高樓峽谷則表現(xiàn)為“星座殘缺-信號(hào)混淆-動(dòng)態(tài)中斷”的動(dòng)態(tài)波動(dòng)失效。兩種場(chǎng)景的失效本質(zhì)都是“衛(wèi)星信號(hào)傳播異?！?，但因環(huán)境封閉性、遮擋物特性不同，失效模式存在明顯差異。GNSS