無源毫米波實時成像理論與關(guān)鍵技術(shù)課件

NonlinearRangeCellMigration(RCM)CompensationMethodforSpaceborne/AirborneForward-LookingBistaticSAR

ZheLiu,JianyuYang,XiaolingZhangSchoolofElectronicEngineering,UniversityofElectronicScienceandTechnologyofChina,Chengdu,611731,ChinaPresentationby

ZheLiuNonlinearRangeCellMiOutlineIntroductiontotheSA-FBSARanditsnonlinearRMCNonlinearRCMcompensationmethodSimulationresultsConclusionsandfurtherworkOutlineIntroductiontotheSA-Introduction－WhatisSA-FBSARSpaceborne/AirborneForward-LookingBistaticSAR(SA-FBSAR)Platforms:TransmitterandreceiverofSA-FBSARarelowearthorbit(LEO)satellite

andaircraft,respectively.WorkingModes:Transmitterantennaworksinside-lookingorsquint-lookingmode;receiverantennainforward-lookingmode.Targetimagingscene:Targetsceneisalongthereceiver’sforward-lookingdirectiontransmitterreceiverImagingsceneIntroduction－WhatisSA-FBSARSIntroduction－EmergenceofSA-FBSARMonostaticSARBistatic/MultistaticSAR(B/MSAR)SpaceborneB/MSARAirborneB/MSARS-AB/MSARCommu.satelliteBroadcastsatelliteRadarsatelliteDiversityoftargetinformationHighimmunitytoattacksLowcostWidecoverage,highSNRPlatformflexibilityPowersavingwidebandrepeatedobservationSA-BSARwithradarsatelliteSA-FBSARattractivepotentialforaircraftlandingandnavigationIntroduction－EmergenceofSA-FIntroduction－EmergenceofSA-FBSARInNov.2009,FGAN(GermanAerospaceCenter)launchedthefirstexperimenttotestthefeasibilityofSA-FBSAR.Fig.1ImagingresultofthefirstSA-FBSARfeasibilityexperimentin2009Introduction－EmergenceofSA-FIntroduction－ChallengesofSA-FBSARimaging

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DramaticgeometricdifferenceSatelliteheight：500-800kmAircraftheight：1-5km

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EssentialvelocitydifferenceSatellitevelocity：7.4-7.6km/sAircraftvelocity：100m/s

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DifferentworkingmodeSatellite:side-lookingAircraft:forward-lookingIntroduction－ChallengesofSA-Introduction－ChallengesofSA-FBSARimaging

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Dramaticgeometricdifference

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Essentialvelocitydifference

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DifferentworkingmodeRangecellmigration(RCM)featuresare:Varywiththetarget’srangeandazimuthlocationexhibitssignificantnonlinearitywithtarget’srangelocationSeveredistortionandnonlinearmisregistrationwilloccur,ifsuchRCMisnotproperlycompensatedIntroduction－ChallengesofSA-Introduction－effectofnonlinearRCMonimagingresultsFig2.Imagingresultofpointtargets(a)originalpointscatterers(b)withoutRCMcompensationIntroduction－effectofnonlinexy(a)originalareatarget(b)WithoutRCMCIntroduction－effectofnonlinearRCMonimagingresultsFig3.Imagingresultofareatargetsxy(a)originalareatarget(b)Introduction－OurworkPurpose:findanonlineartwo-dimensionalRCMcompensationmethodforSA-FBSARinfrequencydomainMainidea:SetupSA-FBSARresponsespectrummodelDeducenonlinearRCManalyticformulaProposeSA-FBSARnonlinearRCMcompensationmethodIntroduction－OurworkPurpose:NonlinearRCMCompensationforSA-FBSAR

－systemgeometricmodelFig.4SA-FBSARsystemgeometryNonlinearRCMCompensationfor.

OriginofnonlinearRCM.OriginofnonlinearRCMNonlinearRCMCompensationforSA-FBSAR

－systemsignalspectrummodelNonlinearRCMCompensationforNonlinearRCMCompensationforSA-FBSAR

－nonlinearRCManalyticformulaNonlinearRCMCompensationforNonlinearRCMCompensationforSA-FBSAR

－nonlinearRCManalyticalformulaNonlinearRCMCompensationforNonlinearRCMCompensationforSA-FBSAR

－nonlinearRCMcompensationmethodFig.5flowchartofnonlinearRCMcompensationmethodforSA-FBSAR,NonlinearRCMCompensationforSimulation－ParametersParametersTransmitterReceiverHeight(km)5143velocity(m/s)7600100azimuthbeamwidth(degree)0.332.9maximumsteeringangle(degree)0.7515depressionangle(degree)3768beamvelocity(m/s)2100700integrationduration(s)0.43pulsewidth(μs)2centralfrequencyoftransmittingsignal(GHz)9.65bandwidthoftransmittingsignal(MHz)60pulserepetitionfrequency(Hz)2500Simulation－ParametersParametSimulation－Pointscatterers(a)originalpointscatterers(b)withoutRCMcompensation(d)withtheproposedmethod(c)withRCMCMethodinRef[1]Ref[1]:X.Qiu,D.HuandC.Ding,IEEEGeosci.RemoteSens.Lett.,4,735-739,2008.

Fig.6Imagingresultsof15pointscattersSimulation－Pointscatterers(Simulation－Pointscatterers(a)errorinrangeposition(b)errorinazimuthpositionSimulation－Pointscatterers(Simulation－areatargetxyFig.7Imagingresultsofareatarget(a)originalareatarget(b)WithoutRCMC(c)WiththeproposedRCMcompensationSimulation－areatargetxyFig.Fig.8two-dimensionalresolutionperformance(a)Contourofidealresolutioncell’sarea(unit:m2)(b)targetlocatedat(500,100)(c)targetlocatedat(0,0)Fig.8two-dimensionalresolutiSimulationFromtheabovesimulationresults,wecouldfindthat:

UncompensatedRCMcoulddeteriorateimagingresultseverely,causenonlineardistortion

RCMcompensationmethoddesignedforotherFBSARsystemcouldnotcompensatethenonlinearRCM,thuscouldnotbeappliedtoSA-FBSAR.

TheproposedRCMcompensationmethodcouldeffectivelycompensatethenonlinearRCMinSA-FBSAR,and