1.Meaning
Inelectronics,amultiplexer(multiplexerormux)canselectasignalfrommultipleanalogordigitalinputsignalsandforwardittoDifferentselectedsignalsareoutputtothesameoutputline.
Multiplexingtechnologymayfollowoneofthefollowingprinciples,suchas:TDM,FDM,CDMorWDM.Multiplexingtechnologyisalsoappliedtosoftwareoperations,suchas:simultaneoustransmissionofmulti-threadedinformationstreamstoequipmentorprograms.
2.Significance
Thepurposeofusingamultiplexeristomakefulluseofthecapacityofthecommunicationchannelandgreatlyreducethecostofthesystem.Forexample,forapairoftelephonelines,itscommunicationfrequencybandisgenerallyabove100kHz,andthefrequencybandofeachtelephonesignalisgenerallylimitedtobelow4kHz.Atthistime,thecapacityofthechannelisfargreaterthantheinformationtransmissionvolumeofaphone.
Usingamultiplexer,multiplechannelsofdatainformationcanshareonechannel.Whenthedatastreamonthemultiplexedlineiscontinuous,thissharingmethodcanachievegoodresults.Obviously,thisismoreeconomicalthanusingacommunicationlineforeachterminal.Multiplexersarealwaysusedinpairs.Onecontinuousterminal,theothernearthehost,itsfunctionistoseparatethereceivedcompositedatastreamaccordingtothechannel,andsendthemtothecorrespondingoutputline,soitiscalledademultiplexer.
3.Principle
Themultiplexeristhedataselector,whichisusedtomultiplexthedataofNinputchannelstooneoutputchannel.ThemultiplexerisThereareveryimportantapplicationsindigitalsystems.Theimplementationstructureofthe4-choose1multiplexerisshowninthefigure:
TherearefourchannelsofdataC0toC3inthefigure,whichareselectedfromthefourchannelsofdatabyselectingthecontrolsignalsS2andS1(addresscode)Onewayofdataissenttotheoutputterminalz.
Thetruthtableofthedataselectorisshowninthetable: