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1、CurrentStatusandDevelopingTendencyforHighFrequencyCommunicationsAbstract:Highfrequency(HF)communicationsplayanimportantroleinthefieldoftheircommunicationsbecauseoftheirskywavepropagationcharacteristics.Inthispaper,twoadvancedHFradiosareselectedtointroducethecurrentstat
2、usforHFcommunications.AfteranalyzingthedemandforfutureHFcommunications,thedevelopingtendencyforHFcommunicationstechniquesisalsopresented.Keywords:highfrequency(HF)communications；adaptive；highspeedmodem；anti-jam；network1IntroductionTheshortwavecommunicationsaidthatthehi
3、ghfrequency(HF)correspondence,thefrequencyofusescopeis3~30MHz,mainlyusestheskywaveaftertheionosphericreflection,doesnotneedtoestablishrelaystationthentorealizetheremotecommunication.Simultaneouslybecausetheionizedlayercannotdestroythecharacteristic,theshortwavecommunic
4、ationisoneofthroughoutmilitarycommandimportantmeansthatbutmustobtainamorewidespreadapplication,theshortwavecommunicationalsowaitsforinthefollowingseveralaspectsenhancing:1)Correspondencereliability.Shortwavecommunicationskywavedisseminationbecauseofionizedlayerchangean
5、dmultipathpropagationinfluence,butisextremelyunstable,signalingmulti-diameterphenomenonisserious,retardsinabigway,theDopplershiftisbig,declinesseriously.Simultaneouslytheshortwavechannelisthebandwidththechannelwhichlimits,theradio-frequencyspectrumisbeencrowded,between
6、thechanneldoestoharassseriously,obtainsthereliablecorrespondencequalityhasbeentheshortwavecommunicationpursuegoal.2)Datatransferrate.Thetraditionshortwavecommunicationriseswithdifficultyasubstantialclauseisdatatransferrateisverylow(doesnotsurpass600bit/s).Ininformation
7、izedwarthemilitarycorrespondencetransmission'sinformation,hasdevelopedfromthesimpledirectionordertosuchastheradarsoundingdata,thecomputedresult,thehighspeedimagefacsimileandsoonsomerequeststhedatatopassonthespeedhighinformation.1)Antijammingability.Becausetheshortwavec
8、ommunicationisunderthewarconditiondirectortheonlyreliableway,rateshortwavedisturbanceequipmentdevelopsalongwiththedis
