简介:RadarSystemEngineering¥DaleR.Billetter(RaytheonCompany,Massachusetts.USA)WHATISRADARSYSTEMENGINEERING?Anorganizationdesiredto...
简介:Ubiquitousradarisanewradarsystemthatprovidescontinuousanduninterruptedmultifunctioncapabilitywithinacoveragevolume.Continuouscoveragefromclose-in'pop-up'targetsincluttertolong-rangetargetsimpactsselectionofwaveformparameters.Thecoherentprocessinginterval(CPI)mustbelongenoughtoachieveacertainsignal-to-noiseratio(SNR)thatensurestheefficiencyofdetection.TheconditionofdetectioninthecaseoflowSNRisanalyzed,andthreedifferentcasesthatwouldoccurduringintegrationarediscussedandamethodtodeterminetheCPIispresented.ThesimulationresultsshowthattargetsdetectionwithSNRaslowas-26dBintheexperimentalsystemcanpossiblydeterminetheCPI.
简介:PrologtotheSectiononRadarSystemEngineering¥//IntheEnglishlanguagewehaveanexpressionthatsaysitispossible"tolosesightofthefores...
简介:714SDDOPPLERWEATHERRADARSYSTEM¥GeRunsheng(葛润生),ZhangPeiyuan(张沛源)andPengHong(彭红)714SDDOPPLERWEATHERRADARSYSTEMGeRunsheng(葛润生),...
简介:Duetothegoodperformanceoftrackinglowelevationtargetascomparedtomicrowaveandthesuperiorityinpenetratingsmoke,dust,fog,anddrysnowascomparedtoinfrared,aKuandKadualbandexperimentalradarwasdesignedanddeveloped.ThisKuandKadualbandexperimentalradarisanarnplitute-comparisonmonopulsetrackingandguidingradar.Theconstitutionandparametersofthisradarisdescribedinparagraph2.Paragraph3dealswithtwoexperimentsfortestingthetrackingperformancesagainstlowelevationtarget,andgivestheimportantresults.BothKuandKabandhavehightrackingprecisionwhentheytrackhighelevationtargets,whileKabandhasmuchbettertrackingperformancethanKubandwhentheytracklowelevationtargets.Kabandcantrackahelicopter,whoseradarcrosssectionisabout6squaremeters,at40m,20m,10m,andeven5mabovesea.Kubandcanonlytrackthesamehelicopterat160mandhigherabovesea.
简介:Themainfunctionofelectronicsupportmeasuresystemistodetectthreatingsignalsinordertotakecountermeasuresagainstthem.Toaccomplishthisobjective,aprocessofassociatingeachinterleavedpulsewithitsemittermustbedone.Thisprocessistermedsortingorde-interleaving.Anovelpointsymmetrybasedradarsorting(PSBRS)algorithmisaddressed.Inordertodealwithallkindsofradarsignals,thesymmetrymeasuredistanceisusedtoclusterpulsesinsteadoftheconventionalEuclideandistance.Thereferencepointsofthesymmetricalclustersareinitializedbythealternativefuzzyc-means(AFCM)algorithmtoamelioratetheeffectsofnoiseandthefalsesorting.Besides,thedensityfiltering(DF)algorithmisproposedtodiscardthenoisepulsesorclutter.Theperformanceofthealgorithmisevaluatedundertheeffectsofnoiseandmissingpulses.IthasbeenobservedthatthePSBRSalgorithmcancopewithalargenumberofnoisepulsesanditiscompletelyindependentofmissingpulses.Finally,PSBRSiscomparedwithsomebenchmarkalgorithms,andthesimulationresultsrevealthefeasibilityandefficiencyofthealgorithm.
简介:PreliminaryresultsofthewindvelocityestimationusingtheMaximumEntropyMethod(MEM)toMUradarobservationdatasetsarepresented.ThecomparisonoftheresultsfromtheperiodogrammethodandtheMEMshowsthattheMEMestimationisreliable,andhashigheraccuracy,resolutionanddetectabilitythantheestimationfromperiodogrammethod.ThehighaccuracypowerspectrumobtainedbytheMEMisveryusefultostudyingtheatmosphericturbulencestructure.However.theMEMneedsthelongercomputingtimeforobtainingthehighaccuracyspectrum.Particularly,theestimationofMEMwillbringseriousdevia-tionatlowersignal-to-noiseratio.
简介:Adopting'simultaneoustransmitting,simultaneousreceiving'operationalscheme,instantaneouspolarizationradar(IPR)canmeasuretargetpolarizationscatteringmatrix(PSM)usingonlyoncetargetechoesintwoorthogonalpolarizationchannels.Firstly,signalmodelandsignalprocessareadvancedundernarrowbandcondition.Secondly,measurementperformancesoftwotypicalIPRwaveformsareanalyzedindetail.Atlast,fieldexperimentsarecarriedoutusingX-bandIPRsystemdesignedbyNationalUniversityofDefenseTechnology(NUDT),China.Comparedwithresultsobtainedbyalternativepolarizationmeasurementscheme,followingresultscanbeobtained:thedifferenceofrelativeamplitudemeasurementresultsissmallerthan2dBandthatofrelativephasemeasurementresultsissmallerthan10?,verifyingthevalidityofinstantaneouspolarizationmeasurementscheme.
简介:AnewSuboptimalMaximumLikelihoodEstimation(SMLE)algorithmbasedonfull-derampmodelanditsimplementationinsatellite-borneradaraltimeterarepresented,withemphasisontheinfluenceofboththereturnfluctuationandthereceivernoiseonheightandslopeestimationprecision.Someconclusionsareobtainedandverifiedbycomputersimulation.
简介:Anoptimizationmethodisbasedtodesignasnowfallestimatemethodbyradarforoperationalsnowwarning,anderrorestimationisanalyzedthroughacaseofheavysnowonMarch4,2007.Threemodifiedschemesaredevelopedforerrorscausedbytemperaturechanges,snowflaketerminalvelocity,thedistancefromtheradarandcalculationmethods.Duetotheimprovements,thecorrelationcoefficientbetweentheestimatedsnowfallandtheobservationis0.66(exceedingthe99%confidencelevel),theaveragerelativeerrorisreducedto48.74%,andthemethodisabletoestimateweaksnowfallof0.3mm/handheavysnowfallabove5mm/h.Thecorrelationcoefficientis0.82betweentheestimatedsnowfallfromthestations50to100kmfromtheradarandtheobservation.Theimprovedeffectisweakwhentheinfluenceofthesnowflaketerminalvelocityisconsideredinthosethreeimprovementprograms,whichmayberelatedtotheuniformecho.Theradarestimateofsnow,whichisclassifiedbythedistancebetweenthesampleandtheradar,hasthemostobviouseffect:itcannotonlyincreasethedegreeofsimilarity,butalsoreducetheoverestimateandtheundervaluationoftheerrorcausedbythedistancebetweenthesampleandtheradar.Theimprovedalgorithmfurtherimprovestheaccuracyoftheestimate.Theaveragerelativeerrorsare31%and27%fortheheavysnowfallof1.6to2.5mm/handabove2.6mm/h,respectively,buttheradaroverestimatesthesnowfallunder1.5mm/handunderestimatesthesnowfallabove2.6mm/h.Radarechomaynotbesensitivetotheintensityofsnowfall,andtheconsistencyshownbytheerrorcanbeexploitedtoreviseandimprovetheestimationaccuracyofsnowforecastintheoperationalwork.
简介:3-D雷达反射率数据向对流规模在数据吸收为使用变得日益重要数字天气预言以及下一代降水评价。典型地,从多重雷达的反射率数据客观地被分析并且mosaiced到地区性的3-D上在被吸收进模型以前的笛卡儿的格子。与多雷达观察的马赛克联系的科学问题之一是所有观察的同步。后来,雷达数据很快通常被更新(∼every510min),由假设暴风雨在窗口以内是稳定的在一个时间窗口以内联合多重radar'观察在当前的多雷达马赛克技术是普通的。假设为慢发展降水系统成立很好,要不是快发展对流暴风雨,这个假设可以被违背,在不同时间的雷达观察的马赛克可以导致不精密的暴风雨结构描写。这研究用追踪算法的多尺度的暴风雨在多重雷达数据分析在暴风雨结构上调查同步的影响。
简介:Windshearreflectsthatthewindfieldisnotuniform,whichisoneoftheprimaryfactorswhichmaketheretrievalofthewindfielddifficult.Basedonvolumevelocityprocess(VVP)windfieldretrievaltechnique,theintensityofwindshearisidentifiedinthispaper.Afteranalyzingthetraditionaltechniquesthatrelyonthedifferenceofradialvelocitytoidentifywindshear,afixeddifferenceamongradialvelocitiesthatmaycausefalseidentificationinauniformwindfieldwasfound.Becauseofthenon-uniformityinwindshearareas,thedifferenceofretrievedresultsbetweensurroundinganalysisvolumescanbeusedasameasurementtoshowhowstrongthewindshearis.AccordingtotheanalysisofasevereconvectiveweatherprocessthatoccurredinGuangzhou,itcanbefoundthattheareasofwindshearappearedwiththestrengthsignificantlylargerthaninotherregionsandthemagnitudegenerallylargerthan4.5m/(s·km).Besides,bycomparingthevariationofwindshearstrengthduringtheconvection,itcanbefoundthatnewcellswillbemorelikelytogeneratewhenthestrengthisabove3.0m/(s·km).Therefore,theanalysisofstrongwindshear'smovementanddevelopmentishelpfultoforecastingsevereconvections.
简介:Featurereductionisakeyprocessinpatternrecognition.Thispaperdealswiththefeaturereductionmethodsforatime-shiftinvariantfeature,powerspectrum,inRadarAutomaticTargetRecognition(RATR)usingHigh-ResolutionRangeProfiles(HRRPs).Severalexistingfeaturereductionmethodsinpatternrecognitionareanalyzed,andaweightedfeaturereductionmethodbasedonFisher'sDiscriminantRatio(FDR)isproposedinthispaper.AccordingtothecharacteristicsofradarHRRPtargetrecognition,thisproposedmethodsearchestheoptimalweightvectorforpowerspectraofHRRPsbymeansofaniterativealgorithm,andthusreducesfeaturedimensionality.Comparedwiththemethodofusingrawpowerspectraandsomeexistingfeaturereductionmethods,theweightedfeaturereductionmethodcannotonlyreducefeaturedimensionality,butalsoimproverecognitionperformancewithlowcomputationcomplexity.Intherecognitionexperimentsbasedonmeasureddata,theproposedmethodisrobusttodifferenttestdataandachievesgoodrecognitionresults.