Spars frequency transmit and receive waveform design

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1、I.INTRODUCTIONUltra-widebandwidth(UWB)syntheticapertureSparseFrequencyTransmitandradars(SARs)appliedtofoliagepenetration(FOPEN)operateusuallyintheVHFandUHFbandstoReceiveWaveformDesignreduceattenuationduetovegetation[1].ThisRFregioncontainsnumerousassignedbandswithstrongemitters.Also,therearebandst

2、hatcannotberadiatedinto,suchasthosededicatedfornavigation.Frequencyfilteringofeitherthetransmitorreceivewaveformorbothleadstoincreasedrangesidelobes.MICHAELJ.LINDENFELDScienceApplicationsInternationalCorp.Previousinvestigationshaveconcentratedoninterferencesuppressioninthereceiver.Fornarrowbandint

3、erference,frequency,amplitude,andphaseofmultiplepuretonesareestimatedandAcomputationallyefficientalgorithmderivescomplexdigitalsubtracted[2—6].Receive-onlyprocessingduringtransmitandreceiveultra-widebandradarandcommunicationeveryotherpulsemaybeusedtoestimatenoisetowaveformswithexcellentarbitraryfr

4、equencybandsuppressionsubtractonthesucceedingpulsewhenthetransmitterisoperating[6],althoughthepulserepetitionandrangesidelobeminimization.Thetransmitwaveformfrequency(PRF)isreduced.However,forwidebandminimizesascalarfunctionpenalizingweightedspectralenergyinterference,correlationtimesmaybecomparab

5、leinarbitraryfrequencybands.Nearconstantpowerresultsfromtothepulserepetitioninterval.Also,somepuretoneanotherpenaltyfunctionfordeviationsfromconstantpower,orestimationalgorithmsareiterative[2,4,5]andmanyconstantpowerisenforcedbyaphase-onlyformulation.Next,tensoftonesormoremayrequiresubtraction.Ale

6、astaleastsquaressolutionforthereceivewaveformminimizesameansquare(LMS)algorithmestimatesincomingweightedsumofsuppressedbandspectralenergyandrangeinterferenceforsubtraction[7—9].sidelobes(forpulseandcontinuouswaveoperation),withaAnotheralgorithmapproachisnotchfiltering,mainloberesponseconstraint.Bo

7、thwaveformsarecalculatedbywhichdoesnotdependonaccurateinterferenceiterativealgorithmswhoseupdatesrequireonlylinearorderincoherentwaveformestimates.Anonadaptivememoryandcomputation,permittingquickcalculationoflong