资源描述：
《Quadrature_signals》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、DSPTrainingDSPClassQUADRATURESIGNALS:COMPLEX,BUTNOTCOMPLICATEDbyRichardLyonsIntroductionQuadraturesignalsarebasedonthenotionofcomplexnumbersandperhapsnoothertopiccausesmoreheartachefornewcomerstoDSPthanthesenumbersandtheirstrangeterminologyofj-operator,complex,imaginary,re
2、al,andorthogonal.Ifyou'realittleunsureofthephysicalmeaningofcomplexnumbersandthej=-1operator,don'tfeelbadbecauseyou'reingoodcompany.WhyevenKarlGauss,onetheworld'sgreatestmathematicians,calledthej-operatorthe"shadowofshadows".Herewe'llshinesomelightonthatshadowsoyou'llnever
3、havetocalltheQuadraturePsychicHotlineforhelp.Quadraturesignalprocessingisusedinmanyfieldsofscienceandengineering,andquadraturesignalsarenecessarytodescribetheprocessingandimplementationthattakesplaceinmoderndigitalcommunicationssystems.Inthistutorialwe'llreviewthefundament
4、alsofcomplexnumbersandgetcomfortablewithhowthey'reusedtorepresentquadraturesignals.Nextweexaminethenotionofnegativefrequencyasitrelatestoquadraturesignalalgebraicnotation,andlearntospeakthelanguageofquadratureprocessing.Inaddition,we'llusethree-dimensionaltimeandfrequency-
5、domainplotstogivesomephysicalmeaningtoquadraturesignals.Thistutorialconcludeswithabrieflookathowaquadraturesignalcanbegeneratedbymeansofquadrature-sampling.WhyCareAboutQuadratureSignals?Quadraturesignalformats,alsocalledcomplexsignals,areusedinmanydigitalsignalprocessingap
6、plicationssuchas:-digitalcommunicationssystems,-radarsystems,-timedifferenceofarrivalprocessinginradiodirectionfindingschemes-coherentpulsemeasurementsystems,-antennabeamformingapplications,-singlesidebandmodulators,-etc.Theseapplicationsfallinthegeneralcategoryknownasquad
7、ratureprocessing,andtheyprovideadditionalprocessingpowerthroughthecoherentmeasurementofthephaseofsinusoidalsignals.Aquadraturesignalisatwo-dimensionalsignalwhosevalueatsomeinstantintimecanbespecifiedbyasinglecomplexnumberhavingtwoparts;whatwecalltherealpartandtheimaginaryp
8、art.(Thewordsrealandimaginary,althoughtraditional,areunfortunatebecausetheirofmeaningsino
