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COMPARISONOFGEOMETRY-BASEDDOPPLERAMBIGUITYRESOLVERINSQUINTSAR

&

WenchaoLiUniversityofElectronicScienceandTechnologyofChinaANINDIRECTDOPPLERRATEESTIMATIONSCHEMEOFSARINLOW-CONTRASTSCENE

COMPARISONOFGEOMETRY-BASEDDIntroductionSyntheticApertureRadar(SAR)Animportantremotesensingtool.MonostaticSARBistaticSARStripmapSARScanSARSpotlightSARSide-lookingSARSquint-lookingSAR……IntroductionSyntheticApertureIntroductionSquintSARGeometrymodelSquintangleIntroductionSquintSARGeometryIntroductionSquintSARRangeHistory：ThelineartermisrangewalkThequadratictermisrangecurvature

IntroductionSquintSARRangeHiIntroductionDopplercentroid()Dopplerrate()Afterrangewalkcorrection,theazimuthdatacanbemodeledasalinearfrequencymodulated(LFM)signal,SignalmodelIntroductionAfterrangewalkcIntroductionInprinciple,itispossibletocomputeDopplerparameterfrompriorinformationprovidedbyGPS/INS,butmeasurementuncertaintiesontheinformationwilllimittheaccuracy.IntroductionInprinciple,itiIntroductionAnincorrectDopplercentroid

alossofSNR;anincreaseintheazimuthambiguitylevel;ashiftinthelocationofthetarget;…...

IncorrectDopplerrateCorrectDopplerrateAnincorrectDopplerratewouldblurtheimage.IntroductionAnincorrectDopplIntroductionTherefore,DopplerparameterEstimationfromechodataisanessentialprocedureforhighqualitySARprocessingIntroductionTherefore,DopplerDopplercentroidestimation(ResolveDopplercentroidambiguity)DopplercentroidestimationDopplercentroidestimationAsazimuthdataaresampledbypulserepetitionfrequency(PRF),thereisalwaysDopplercentroidambiguity,andthebiggerthesquintangleis,themoreseriousthedopplerambiguitywillbe.Dopplercentroidisusuallyexpressedintwoparts:thebasebandDopplercentroidandDopplerambiguitynumber.DopplercentroidestimationAsDopplercentroidestimationMultiplePRFWavelengthdiversityalgorithm(WDA)Multilookalgorithms(MLCC,MLBF)

Geometry-basedalgorithmsDopplercentroidestimationMuGeometry-basedalgorithmsTherelationshipbetweenDopplercentroidandrangewalkslope,Sincethismethodisbasedonthegeometriccharacteristicsoftherangecompresseddata,itisnamedasageometry-basedDopplerambiguityresolver.ThenDopplercentroidcanbecomputedviaestimatingtherangewalkslope.Geometry-basedalgorithmsTherConventionalRadontransformschemeRadontransform:Awell-knowntoolfordetectingslope.

Itintegratesintensityalongeverypossibledirectionintheimageandmapsthisinformationintoafeaturespace.Itinvolvestwo-dimensionalsearch.Geometry-basedalgorithmsConventionalRadontransformsIterativeschemeTheslopeisseenasasearchingvariable,andentropyisusedtomeasuretherobustnessofsignal.Itutilizesthepriorinformationofplatform,andreplacestheRadontransformwithasimpleintegrationofimageintensityoverazimuth.Geometry-basedalgorithmsIterativeschemeTheslopeissImprovedRadontransformschemeThisschemeutilizespriorinformationofplatform,convertthedataintobinarydata,andconducttwo-stepRadontransform,whichwouldmakeitissparseandreducetheneedtosearchthewholefeaturespace.Geometry-basedalgorithmsImprovedRadontransformschemComparisonsItisobviouslythattheycangivetheaccurateDopplerambiguitynumber.WhilethespeedoftheiterativeschemeandtheimprovedRadontransformschemeismuchfasterthanconventionalRadontransform.ComparisonsItisobviouslythaDopplerrateestimation(Autofocus)DopplerrateestimationParametricMethodMetric-basedAutofocus(Entropy/Contrast)MapDrift(MD)Shiftandcorrelate(SAC)DopplerrateestimationNonparametricMethodProminentPointProcessing(PPP)PhaseGradientAutofocus(PGA)Time-FrequencyAnalysisHighcontrastscene.ParametricMethodDopplerrateLowcontrastsceneLowSNRWithoutprominentpoint

Whatcanwedo?DopplerrateestimationLowcontrastsceneDopplerrateEstimationSchemeAccordingtothefactthatDopplerrateisinverselyproportionaltorange,

ItindicatesthattheDopplerrateinlow-contrastscenecanbeestimatedindirectly.EstimationSchemeAccordingtoEstimationFlowchartDopplerrateinhigh-contrastsceneisestimatedfirstusingRadon-Wignertransform,andthenusingthefactthatDopplerrateisinverselyproportionaltorange,Dopplerrateinlow-contrastsceneisestimatedindirectly.EstimationFlowchartDopplerraResultsHighContrastScene

WithProminentPoint

Timefrequencyanalysis

RadontransformLowContrastScene

WithoutProminentPointTimefrequencyanalysis

RadontransformResultsHighContrastSceneConclusions

Thegeometry-basedschemecanbeusedtoresolveDopplerambiguityofSARwithlargemigration.ThespeedofimprovedRadontransformschemeandtheiterativeschemeisabouttentimesfasterthanconventionalRadontransformscheme.AnindirectestimationschemeofDopplerrateforlowcontrastsceneisdeveloped.Theindirectschemeiseffective,anditcanreducecomputationtimegreatly.ConclusionsThegeometry-baseThankyouforyourlistening!Thankyouforyourlistening!COMPARISONOFGEOMETRY-BASEDDOPPLERAMBIGUITYRESOLVERINSQUINTSAR

&

WenchaoLiUniversityofElectronicScienceandTechnologyofChinaANINDIRECTDOPPLERRATEESTIMATIONSCHEMEOFSARINLOW-CONTRASTSCENE

COMPARISONOFGEOMETRY-BASEDDIntroductionSyntheticApertureRadar(SAR)Animportantremotesensingtool.MonostaticSARBistaticSARStripmapSARScanSARSpotlightSARSide-lookingSARSquint-lookingSAR……IntroductionSyntheticApertureIntroductionSquintSARGeometrymodelSquintangleIntroductionSquintSARGeometryIntroductionSquintSARRangeHistory：ThelineartermisrangewalkThequadratictermisrangecurvature

IntroductionSquintSARRangeHiIntroductionDopplercentroid()Dopplerrate()Afterrangewalkcorrection,theazimuthdatacanbemodeledasalinearfrequencymodulated(LFM)signal,SignalmodelIntroductionAfterrangewalkcIntroductionInprinciple,itispossibletocomputeDopplerparameterfrompriorinformationprovidedbyGPS/INS,butmeasurementuncertaintiesontheinformationwilllimittheaccuracy.IntroductionInprinciple,itiIntroductionAnincorrectDopplercentroid

alossofSNR;anincreaseintheazimuthambiguitylevel;ashiftinthelocationofthetarget;…...

IncorrectDopplerrateCorrectDopplerrateAnincorrectDopplerratewouldblurtheimage.IntroductionAnincorrectDopplIntroductionTherefore,DopplerparameterEstimationfromechodataisanessentialprocedureforhighqualitySARprocessingIntroductionTherefore,DopplerDopplercentroidestimation(ResolveDopplercentroidambiguity)DopplercentroidestimationDopplercentroidestimationAsazimuthdataaresampledbypulserepetitionfrequency(PRF),thereisalwaysDopplercentroidambiguity,andthebiggerthesquintangleis,themoreseriousthedopplerambiguitywillbe.Dopplercentroidisusuallyexpressedintwoparts:thebasebandDopplercentroidandDopplerambiguitynumber.DopplercentroidestimationAsDopplercentroidestimationMultiplePRFWavelengthdiversityalgorithm(WDA)Multilookalgorithms(MLCC,MLBF)

Geometry-basedalgorithmsDopplercentroidestimationMuGeometry-basedalgorithmsTherelationshipbetweenDopplercentroidandrangewalkslope,Sincethismethodisbasedonthegeometriccharacteristicsoftherangecompresseddata,itisnamedasageometry-basedDopplerambiguityresolver.ThenDopplercentroidcanbecomputedviaestimatingtherangewalkslope.Geometry-basedalgorithmsTherConventionalRadontransformschemeRadontransform:Awell-knowntoolfordetectingslope.

Itintegratesintensityalongeverypossibledirectionintheimageandmapsthisinformationintoafeaturespace.Itinvolvestwo-dimensionalsearch.Geometry-basedalgorithmsConventionalRadontransformsIterativeschemeTheslopeisseenasasearchingvariable,andentropyisusedtomeasuretherobustnessofsignal.Itutilizesthepriorinformationofplatform,andreplacestheRadontransformwithasimpleintegrationofimageintensityoverazimuth.Geometry-basedalgorithmsIterativeschemeTheslopeissImprovedRadontransformschemeThisschemeutilizespriorinformationofplatform,convertthedataintobinarydata,andconducttwo-stepRadontransform,whichwouldmakeitissparseandreducetheneedtosearchthewholefeaturespace.Geometry-basedalgorithmsImprovedRadontransformschemComparisonsItisobviouslythattheycangivetheaccurateDopplerambiguitynumber.WhilethespeedoftheiterativeschemeandtheimprovedRadontransformschemeismuchfasterthanconventionalRadontransform.ComparisonsItisobviouslythaDopplerrateestimation(Autofocus)DopplerrateestimationParametricMethodMetric-basedAutofocus(Entropy/Contrast)MapDrift(MD)Shiftandcorrelate(SAC)DopplerrateestimationNonparametricMethodProminentPointProcessing(PPP)PhaseGradientAutofocus(PGA)Time-FrequencyAnalysisHighcontrastscene.ParametricMethodDopplerrateLowcontrastsceneLowSNRWithoutprominentpoint

Whatcanwedo?DopplerrateestimationLowcontrastsceneDopplerrateEstimationSchemeAccordingtothefactthatDopplerrateisinverselyproportionaltorange,

ItindicatesthattheDopplerrateinlow-contrastscenecanbee

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