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1、Ann.Geophysicae18,1242±124732000)óEGS±Springer-Verlag2000Groundcluttercancellationinincoherentradars:solutionsforEISCATSvalbardradar123T.Turunen,J.Markkanen,A.P.vanEyken1EISCATScienti?cAssociation,SE-98123Kiruna,Sweden2EISCATScienti?cAssociation,FIN-99600Sodankylaè,Finl
2、and3EISCATScienti?cAssociation,N-9171Longyearbyen,NorwayReceived:24January2000/Revised:5July2000/Accepted:6July2000Abstract.Incoherentscatterradarsmeasureionospherepowerfulandsensitivesystemsmustbedeployedtoparametersusingmodi?edThomsonscatterfromfreeensureuseablereturn
3、s.Incoherentscatterradarstypi-electronsinthetarget3seee.g.Hagfors,1997).ThecallyuseVHFandUHFfrequenciesthroughseveralintegratedcrosssectionoftheionosphericscatterersisMFinstrumentsalsoexist.extremelysmallandthemeasurementscaneasilybeToobtainadequatespatialandspectralres
4、olution,disturbedbysignalsreturnedbyunwantedtargets.on-oamplitudemodulation,binaryphasemodulation,Groundcluttersignals,enteringviatheantennasidefrequencymodulation,andcombinationsofthesearelobes,canrendermeasurementsatthenearesttargetusedinthetransmittedpulses.Targetban
5、dwidthsvaryrangestotallyimpossible.TheEISCATSvalbardRadarfromhundredsofHertztosometensofkiloHertzand3ESR),whichstartedmeasurementsin1996,suersfrommodulationbandwidthsfromaboutonekiloHertztoseveregroundclutterandtheionospherecannotbehundredsofkiloHertz.Together,thesedict
6、atethemeasuredinanysimplemanneratrangeslessthanaboutreceivingbandwidth,noisebandwidthandsampling120±150km,dependingonthemodulationemployed.Ifintervalsrequired.Insomespecialapplicationsmuchthetargetandcluttersignalshavedierent,andclearlyhigherbandwidthsmustbeaccommodated
7、.Receptionidenti?able,propertiesthen,inprinciple,thereareanddatasamplingusuallystart300±500microsecondsalwayswaystoeliminatetheclutter.Inincoherentaftertheendoftransmittedpulse,forthosemodulationsscattermeasurements,dierencesinthecoherencetimestobeusedatthelowestrangeso
8、fthetarget.Theupperofthewantedandunwantedsignalscanbeusedforlimitofthepossiblereceptionwindowissetbythepointcl
