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1、CurrentStatusandDevelopingTendencyforHighFrequencyCommunicationsAbstract:Highfrequency(HF)communicationsplayanimportantroleinthefieldoftheircommunicationsbecauseoftheirskywavepropagationcharacteristics.Inthispaper,twoadvancedHFradiosareselectedtointroducethecurrentstatusforHFcommunicatio
2、ns.AfteranalyzingthedemandforfutureHFcommunications,thedevelopingtendencyforHFcommunicationstechniquesisalsopresented.Keywords:highfrequency(HF)communications；adaptive；highspeedmodem；anti-jam；network1IntroductionTheshortwavecommunicationsaidthatthehighfrequency(HF)correspondence,thefrequ
3、encyofusescopeis3~30MHz,mainlyusestheskywaveaftertheionosphericreflection,doesnotneedtoestablishrelaystationthentorealizetheremotecommunication.Simultaneouslybecausetheionizedlayercannotdestroythecharacteristic,theshortwavecommunicationisoneofthroughoutmilitarycommandimportantmeansthatbu
4、tmustobtainamorewidespreadapplication,theshortwavecommunicationalsowaitsforinthefollowingseveralaspectsenhancing:1)Correspondencereliability.Shortwavecommunicationskywavedisseminationbecauseofionizedlayerchangeandmultipathpropagationinfluence,butisextremelyunstable,signalingmulti-diamete
5、rphenomenonisserious,retardsinabigway,theDopplershiftisbig,declinesseriously.Simultaneouslytheshortwavechannelisthebandwidththechannelwhichlimits,theradio-frequencyspectrumisbeencrowded,betweenthechanneldoestoharassseriously,obtainsthereliablecorrespondencequalityhasbeentheshortwavecommu
6、nicationpursuegoal.2)Datatransferrate.Thetraditionshortwavecommunicationriseswithdifficultyasubstantialclauseisdatatransferrateisverylow(doesnotsurpass600bit/s).Ininformationizedwarthemilitarycorrespondencetransmission'sinformation,hasdevelopedfromthesimpledirectionordertosuchastheradars
7、oundingdata,thecomputedresult,thehighspeedimagefacsimileandsoonsomerequeststhedatatopassonthespeedhighinformation.1)Antijammingability.Becausetheshortwavecommunicationisunderthewarconditiondirectortheonlyreliableway,rateshortwavedisturbanceequipmentdevelopsalongwiththedis
