broadcast

Introduction

Broadcasting:guǎngbō

English:Radiobroadcasting;Broadcast;Beontheair;Airing

Cantonesepronunciation:gwong2bo3

Broadcastingisthemostcommonformofmultipointdelivery.Itdeliversacopyofthepackettoeachdestinationstation.Itcanbecompletedbythedeliveryofmultiplesinglepackets,oracopyofthepacketcanbedeliveredthroughaseparateconnection,untileachreceiverreceivesacopy.

Anewsdisseminationtoolthattransmitssoundthroughradiowavesorwires.Theprogramthattransmitsprogramsthroughradiowavesiscalledwirelessbroadcast,andtheprogramthattransmitsprogramsthroughwiresiscalledcablebroadcast.

History

Birth

EarlyBroadcasting

OnChristmasEvein1906,FessendenandAlexandreintheUnitedStatesXunsetuparadiostationnearNewYorkandbroadcastforthefirsttimeever.Thecontentofthebroadcastistwojokes,asongandaviolinsolo.Thisradioprogramwasclearlyheardbythepeoplewhohadreceiversscatteredaroundatthattime.

In1908,ForresteroftheUnitedStatesmadeanotherbroadcastontheEiffelTowerinParis,whichwasheardbyallmilitaryradiostationsinthatareaandanengineerfromMarseille.

In1916,ForresterbroadcastednewsaboutthepresidentialelectiononanexperimentalradiostationoftheBronxPressBureau,butatthattimeonlyahandfulofpeoplewereabletolistentotheseearlybroadcasts.

Realbroadcastingwasborninthe1920s.

Theworld’sfirstlicensedradiostation,KDKA,Pittsburgh,USA,officiallystartedbroadcastingonNovember2,1920.

China’sfirstradiostationwasbuiltinJanuary1923andwasfoundedbyOsborneintheUnitedStates.ItisaradiostationbelongingtotheChineseRadioBroadcastingCorporationandfirstbroadcastinShanghai.

In1926,China'sfirstself-runradiostation,HarbinRadio,wasfoundedbyLiuHan.

In1928,theChineseKuomintang'sNorthernExpeditionsucceeded,andthecallsignofthe"ChineseKuomintangCentralExecutiveCommitteeBroadcastingRadioStation"wasestablishedinNanjingasXKM.

In1939,theKuomintangestablishedaforeignbroadcastingstationinChongqing—"VoiceofChina"(VoiceofChina).

InDecember1940,thePeople’sBroadcastingCorporationofChinawasestablished,thepredecessoroftheCentralPeople’sBroadcastingStation-Yan’anXinhuaBroadcastingStation.

Theadvantageofbroadcastingisthatithasawiderangeoftargets,rapidspread,diversefunctions,andstrongappeal;theshortcomingsarefleeting,listeninginorder,nochoice,anddifficultyinlisteningifthelanguageisnotclear.(Thepictureontherightshowsthe6.5-kilowattradiotransmitteroftheAmericanMarconiCompanyin1919)

Development

Duetothewidespreaduseofradiosandpeople’sattentiontohigh-powertransmittersandhigh-sensitivityelectronictubereceptionTheproficientmasteryofcomputerskillshasgraduallymadebroadcastingareality.

In1919,theSovietUnionmadeahigh-powertransmitter,andin1920beganexperimentalbroadcastinginMoscow.

OnJune15,1920,Marconihelda"Radio-Telephone"concertstarringMrs.MelbaintheUnitedKingdom,asfarasParis,Italy,Norway,andevenGreeceCanbeheardclearly.Thisisthebeginningofthebroadcastingbusiness.

OnNovember2,1920,undertheguidanceofConrad,theWestinghouseradiostationKDKAbeganbroadcasting.ThefirstbroadcastprogramwastheHarding-Coxpresidentialelection.Atthattime,thismatterwasasensation.

OnDecember22,1920,theKöniwursthausenradiostationinGermanybroadcastedaconcertofinstrumentalmusicforthefirsttime.

OnNovember14,1922,theLondonZLOradiostationofficiallybeganbroadcastingdailyprogramsintheUnitedKingdom.ThestationwaschangedtotheBritishBroadcastingCorporation,orBBC,in1927.

In1922,theEiffelTowerinFrancealsoofficiallybeganbroadcasting.

Asof1927,therewerealready737radiostationsintheUnitedStates.

Inthisperiod,broadcastingstationshavesprungupinvariouscountries.Atthattime,broadcastinginEuropehadbeenregardedasahugecommunicationtool.Sincethen,thebroadcastingindustryintheworldhascontinuedtodevelop,andaglobalbroadcastingnetworkhasgraduallyformed.

Howtolisten

Terminalreception

Youcanlistentothebroadcastbyreceivingsignalsfromterminaldevicessuchasradios,butyoucanonlylistentoalimitednumberofchannels.

Onlinelistening

Nowadays,manyradiostationsprovideInternetlisteningservices,andmanywebsiteshavecollectedthelisteningaddressesoftheseradiostations.UserscanlistentoradioprogramsonlinethroughtheInternet.

Relatedcompanies

JiangsuBroadcastingGroup

AccordingtoasurveyofJiangsuBroadcastingandTelevisionGroup,thegroupachieved5.624billionyuaninrevenueinthefirsthalfoftheyear.,Ayear-on-yearincreaseof1.368billionyuan,anincreaseof32.2%.

Theamountofradioandtelevisionadvertisingreceiptsincreasedby17.22%year-on-year.Amongthem,JiangsuSatelliteTV'sreceiptsincreasedby19.43%year-on-year,andHappyEducationCorporationincreasedby63.38%year-on-year.Emergingbusinessesareadvancingsteadily.Newmediabusinessrevenueincreasedby35.6%year-on-year.

ChinaFilmGroup

AccordingtotheinvestigationofChinaFilmGroup,thegroupopened6newtheatersinthefirsthalfoftheyear,with44screensand7,469seats.Asofthefirsthalfoftheyear,ChinaFilmHoldingshad55cinemaswith361screensand59,040seats.

Accordingtopreliminarystatistics,theoperatingincomeofChinaFilmCorporationinthefirsthalfof2012was2.06billionyuan,ayear-on-yearincreaseof800millionyuan,anincreaseof79.27%,whichwasmuchhigherthanthe41%growthrateofthenationalmovieboxoffice,andtheoveralltotalprofitwasrealized.514millionyuan,anincreaseof120.01%overthesameperiodin2011.

Privatecarradio

Theprofessionalizationofradiofrequencyhasbecomeatrendinthedevelopmentofurbanradiostations.Thefunctionalbreakdownofprofessionalradioisaninevitabletrend,andmobileradioisalsowiththeadventoftheautomobileage.Theinevitabledevelopmenttrendofthedevelopmentofbroadcastingmedia.However,judgingfromthecurrentsituationofprivatecarbroadcasting,itismorelikea"unbrandedarmy",with"all-encompassingbutlooseandfragmentedweaknessesgraduallyrevealed."Therefore,thereisstillalotofroomforexplorationinthefieldofprivatecarbroadcasting,andmatureandclearlypositionedprivatecarbroadcastingneedstobeexploredandtempered.Thefollowingistheauthor'svisionforthedevelopmentofprivatecarbroadcasting.

(1)Reducehomogeneouscompetitionandhighlightthecharacteristicsofprivatecars.

Itisundeniablethatthereareoverlapsandconflictsbetweentrafficbroadcastingandprivatecarbroadcastinginareassuchasaudiences,programs,information,andservices,becausebothservethemobilepopulationandusecarsastheCarrier.

However,asaproductoffurtherprofessionalizationandnarrowbroadcastingofradiostations,privatecarbroadcastinghasmoreconcreteandclearpositioningofitsradiostationandaudiencegroup.Therefore,ifprivatecarbroadcastingwantstofindaplaceofitsowninthepopularbroadcastingeraoftrafficbroadcasting,ithastoworkhardonaudiencepositioning,programcontent,personalitycharacteristics,etc.,toreducethedegreeofhomogeneitywithtrafficbroadcasting,andbecomeaprivatecarowner.Onlybyprovidinghigh-endandcaringservicescanitmeetitsrequirementsandmakeitsowncharacteristicsanduniquepositioning.Atthesametime,accordingtothespecifictimeandspaceofprivatecarownersduringtherushhour,theprogramshouldbemoredetailed,accuratelygraspthelifephilosophyandliferhythmoftheprivatecarowner,reasonablydividethetypeofprogram,andtimelyandappropriateinconsultation,roadconditions,music,lifeandotheraspectsProvideservices.

(2)Findapointofresonancewiththeaudience.

"Thefamilylisteningmodeofradiointheeraofprivatecarsmeanstwomoresignificantchanges:oneistocreateanenvironmentwhererarefamilymembersgatherinaclosedspacetoreceiveinformationtogether,andtwoItistheproportionoffemalelistenersthathasgreatlyincreased.”Therefore,privatecarbroadcastingcantakeinformationthatisconcernedaboutfamilylifeasoneofitsowncharacteristics,focusingonissuesthatafamilycaresabout,suchashousingprices,gasprices,orchildren’seducationissues.Throughthesedetailedandspecificprogramcontent,provideintimateandfragmentedservicesforthefamily-basedaudienceinthecar,sothatfamilymemberscancontinuetopayattentiontotheprivatecarbroadcastintheprocessoflisteninganddiscussing,therebystabilizingtheprivatecarbroadcast.Listentothefeatures.

Withtheadventoftheeraofprivatecars,moreandmorewomenarebeginningtomasterthesteeringwheel,whichisinsharpcontrasttothesituationwhereprofessionaldriversaremostlymen.Therefore,privatecarbroadcastingcanbeconsideredfromtheperspectiveoffemaleprivatecarowners,increasefemaletopicsandcontentappropriately,andincreasetheloyaltyandexpectationoffemaleprivatecaraudiencesforprivatecarbroadcasting.

Inaddition,mostoftheprivatecarbroadcastaudiencesareprofessionalworkers,andthedepressionofurbanpeopleonthewaytoandfromgetoffworkisoftennotvented.Accordingtoasurveyof2,750peopleconductedbytheChinaYouthDailySocialSurveyCenter,83.1%ofwhite-collarrespondentsadmittedthattheyhavevaryingdegreesof"off-getoffworksilence."Therefore,privatecarbroadcastingshouldpayattentiontothecatharsisoftheaudience,findtheresonancebetweenthebroadcastingandtheowneroftheprivatecar,andrelievethepressureandrelaxthemindoftheaudience.

(3)Guaranteeprogramqualityandstabilizebrandeffect.

"Thecharacteristicsoftheaudiencegroupofprivatecarbroadcastsareverysignificant:thistypeofbroadcastaudiencesarefirstlyeducated,havealargedemandforinformationconsumption,andaretheleadersandmajorconsumersofsocialculture;Itisbecauseofstrongerconsumptionpower,moreattentiontomid-to-high-endconsumergoods,andstrongerabilitytointerveneandown.”Privatecarownersusuallypursueahigherleveloflife,andthispartoftheaudiencepaysattentiontothequalityoflife.Therefore,inordertomeetthequalityrequirementsandpsychologicalneedsofprivatecarownersandlisteners,privatecarbroadcastingneedstobesophisticated.Nowadays,therearemoreandmoreofflineactivitiesonbroadcastingfrequencies,whichhasbecomeanotheroperatingchannelforbroadcastingstations.Privatecarbroadcastingisgearedtowardsmid-to-high-endprivatecarowners,andwiththesupportoftheautomobileindustry,thereisenoughspaceandstrengthtoestablishabrandandformabrandeffect.Therefore,closelinkagewithrelatedindustriesisconducivetotheformationofauniquebrandeffectforprivatecarbroadcasting.

Transmissionprinciple

Whenbroadcastingaprogram,thesoundisfirstconvertedintoanaudioelectricsignalthroughamicrophone,andthenamplifiedbyahigh-frequencysignal(carrier).Atthistime,thehigh-frequencycarrierAcertainparameterofthesignalchangesaccordinglywiththeaudiosignal,sothattheaudiosignalwewanttotransmitiscontainedinthehigh-frequencycarriersignal.Thehigh-frequencysignalisamplified,andthenthehigh-frequencycurrentflowsthroughtheantennatoformaradiowavedirectionExternaltransmission,thepropagationspeedofradiowavesis3×10^8m/s.Thisradiowaveisreceivedbytheradioantenna,thenamplifiedanddemodulated,restoredtoaudioelectricalsignals,andsenttothespeakervoicecoil,causingthepaperconetorespondaccordingly.Vibrationcanrestoresound,whichistheprocessofacoustic-electricalconversionandtransmission-electric-acousticconversion.

Thefrequencyofmediumwave(high-frequencycarrierfrequency)isspecifiedas525-1605kHz(thousandcycles).

Thefrequencyrangeofshortwaveis3500-18000kHz.

TheinternationalstandardfrequencybandofFMistheveryhighfrequencybandof88-108MHZ.

Radio

Introductiontotheprinciple

Thehigh-frequencysignalreceivedbytheantennapassesthroughtheinputcircuitandtheradio’slocaloscillationfrequency(itsfrequencyishigherthanthatoftheexternalhigh-frequencysignalAfixedintermediatefrequency,thenationalintermediatefrequencystandardstipulatesas465KHZ)issentintothefrequencyconversiontubetomix-frequencyconversion,andanewfrequencyisgeneratedintheloadloop(frequencyselection)ofthefrequencyconversionstage,thatis,theintermediatefrequencygeneratedbythedifferencefrequency(internshipFigure3-2,B)),theintermediatefrequencyonlychangesthefrequencyofthecarrier,theoriginalaudioenvelopedoesnotchange,theintermediatefrequencysignalcanbebetteramplified,theintermediatefrequencysignalisdetectedandthehighfrequencysignalisfilteredout(inpracticeFigure3-2atD).Afterlow-amplificationandpoweramplification,thespeakerispushedtoproducesound.

Thismachineworks

C1andB1formtheantennainputloop.VT1,B2,B1,andCformthefrequencyconversionstage.VT1isafrequencyconversiontube.TheprimarycoilandCformavariablefrequencyload.C1andB2formthelocaloscillatorcircuit,C6istheoscillationcouplingcircuit,VT2andVT3formtheintermediatefrequencyamplifiercircuit,2AP9isthedetectioncircuit,R9isthevolumepotentiometer(withpowerswitch),andC16isthehigh-frequencycouplingcapacitor.

VT4andVT5arepre-lowfrequencyamplifierstages,andVT6andVT7formaClassBpush-pullpoweramplifier.R16,C21,andC17arepowerwavecircuits.R1,R2,R3,R4,R5,R6,R7,R12,R10,R11,R13,R17,R18aretheDCbiasresistorsofeachstage.

Installation

①Analyzethecircuitofthewholemachine,andbefamiliarwiththeinstallationpositionofthecomponentsontheprintedboard.

②Weldingandinstallationofcomponents(thequalityofcomponentsshouldbecheckedduringinstallation).

③Checkthecircuit,andcheckthefollowingcontentsagainsttheinstalledradioandthecircuitschematicdiagram.

a.Checkwhetherthemodels,installationpositionsandpinsofalllevelsoftransistorsarecorrect.

b.Checktheinstallationsequenceofeachlevelinthemiddleandtheweek,andwhethertheleadwiresoftheprimaryandsecondarystagesarecorrect.

c.Checkwhetherthepositiveandnegativeleadsoftheelectrolyticcapacitorareconnectedcorrectly.

d.Whethertheprimaryandsecondaryinstallationpositionsofthemagneticantennacoilswoundinsectionsarecorrect.

e.UseananalogmultimetertomeasuretheresistanceofthewholemachineintheR×100range,connecttheredtestleadtothenegativeleadofthepowersupply,andconnecttheblacktestleadtothepositiveleadofthepowersupply.Themeasuredresistancevalueofthewholemachineshouldbegreaterthan500ohms.

Aftertheabovechecksarecorrect,the4.5voltpowersupplycanbeconnected.

Debuggingofsuperheterodyneradio.Newlyinstalledradio.Itmustbeadjustedtomeettherequirementsofperformanceindicators.Theadjustmentsinclude:adjustingtheoperatingpointsofalllevelsoftransistors,adjustingtheintermediatefrequency,adjustingthecoverage(ie,adjustingthescale)andadjusting(adjustingthefrequencytracking,thatis,thesensitivity).

Adjustmentcontent

①Adjustthestaticoperatingpoint:theroleofeachtransistorisdifferent,andtheoperatingpointatwhichitislocatedisdifferent.Machineoscillationstops)Whenthereisnoexternalsignal,thevoltageontheemitterresistanceofeachtransistorismeasuredseparately.AdjustR1,R4,R12,R17,andR18tomakethevoltageofVT1levelbe-0.5~0.7V.ThevoltageonR6ofVT2levelis-0.5～0.7V.ThevoltageonR7ofVT3is-0.25~0.4V,thevoltageonR14ofVT5is-0.7~0.9V,andthetotalcollectorcurrentofVT6andVT7is2~6mA.

②Adjusttheintermediatefrequency:Thepurposeistoadjusttheresonancefrequencyofthethreeintermediatefrequencytransformers(intermediatefrequencytuningcircuit)toafixedintermediatefrequencyof465KHZ.Sincetheusedintermediatefrequencyisnew,thegeneralmanufacturerhasadjusteditto465KHZ.Therefore,whendebugging,whenreceivingacertainradiostation,useanon-inductivescrewdrivertoadjustthemid-peripheralmagneticcore.Theadjustmentsequenceisfromthelatterstagetothepreviousstage,thatis,adjustBz3firstandthenBz2untiltheloudestspeaker.

③Frequencyadjustmentcoverage(tuningthefrequencyrangeoftheradio535-1605kHz):adjustadial,sothatthedouble-connectedvariablecapacitorsareallscrewedinandout.Thepointersareonthedial530-1630thousand.Turnthedouble-connectedvariablecapacitortoalignthepointertothe640-thousand-cyclescale(CentralPeople’sBroadcastingStation)ontheweeklyline.Useanon-inductivescrewdrivertoturnthecoreoftheoscillatingcoiltolistentothe640-thousand-cycleradiobroadcastwithamoderatesound.Thevariablecapacitormakesthepointeralignnearthe1500thousand-cyclescale.Adjustthefine-tuningcapacitorC3oftheoscillatingcircuittolistentoradiobroadcastsinthevicinityof1500thousandcycles,andadjustthehigh-endandlow-endrepeatedlyseveraltimes.

④Thepurposeofunifiedtuning(adjustingfrequencytracking)istomaketheoscillationfrequencyofthismachineinthereceivingfrequencyrange(mediumband535～1650kHz)and465KHzhigherthanthefrequencyoftheexternalsignal,thatis,theoscillationfrequencyrangeofthismachineis1000kHz～2070kHz.Therefore,C1andC2double-connectedvariablecapacitorswiththesamecapacitanceareusedforsynchronousadjustment.Usuallytrackingisperformedatthreepointsintheselectedfrequencyrange,namely,three-pointunifiedadjustment.Inordertoachieveagoodthree-trackinginthemachineTheoscillatingcircuitisconnectedinserieswithapaddingcapacitorCandatrimmingcompensationcapacitorCinparallel,andacompensationtrimmingcapacitorCisconnectedinparallelintheinputcircuit.Forspecificadjustments,theinputcircuitcompensationcapacitorCzisadjustedtomakethevolumeloudest.

Themid-rangeadjuststolistentothebroadcastnear1000KHZ,sothatthesoundistheloudest.Atthistime,adjusttheCfilmontheflowerfilminthedouble-connectedcapacitormovingfilm,andswitchthefilmdistance.Iftheinputisreducedwhenthepatternismoved,themiddleendisnotdetuned,andthepatternisreturnedtotheoriginalposition.Iftheinputisincreased,thesidelaceneedstobecompensatedbyturning,andthecapacityofthepaddingcapacitorcanalsobechanged..

Programrecording

Broadcastingroom

Boeingacousticallyprocessed,dedicatedtobroadcastingandrecordingbroadcastprogramsRoom.Thebroadcastingroomisrequiredtohavebettersoundinsulationconditionsandnecessaryanti-vibrationfacilitiestopreventsolid-bornesoundtransmission.Indoorceilingsandwallsshouldbeequippedwithavarietyofdifferentsound-absorbingmaterialsanddiffusersinaccordancewiththerequiredreverberationtimeanddiffusesoundfieldindicators.

Accordingtodifferentpurposes,theareaof​​thestudiocanbedividedinto15to80squaremeters.Theareaof​​thelanguagestudioisgenerallylessthan30squaremeters,andthereverberationtimeis0.4to0.5seconds.Theartbroadcastingroomhasalargearea,anddifferentareasanddifferentreverberationtimesaredesignedaccordingtothenumberofactorsandthenatureoftheprogram.Inastudiothatusesthepost-processingtechnologyofmulti-channelrecording,inordertoincreasetheseparationcapacitybetweeneachchannelandpreservetheroomforpost-processing,itisrequiredtosetupfacilitieswithstrongsoundabsorptionandstrongdiffusion.Thereverberationtimeiscontrolledwithin0.5to1second,whichhasnothingtodowiththenumberofactorsandthenatureoftheprogram.

Reverberationroom

Aspecialroomforrecordingwithlongreverberationtimeanddiffusesoundfield.Intheprocessofrecordingorrecordingcopying,inordertoimprovethesoundeffect,itisnecessarytousethereverberationroomtoartificiallyincreasethereverberationorcreatetheechointhesound.Thereverberationtimeisrequiredtobe3to5secondsorlonger.Thesounddiffusivityofthereverberationroomshouldbegood,andpropersoundinsulationandvibrationisolationshouldbedone.Anactivesound-absorbingstructurecanbesetupindoorstochangethereverberationtime.

Broadcastinglevel

Broadcastingisdividedintolayer2broadcastingandlayer3broadcasting.

Layer2broadcast,alsocalledhardwarebroadcast,isusedtosenddatatoallnodesintheLAN,andusuallydoesnotcrosstheboundary(router)oftheLANunlessitbecomesaunicast.ThebroadcastdestinationaddressisanIPaddresswithall1sinbinaryorallFsinhexadecimal(255.255.255.255).

Broadcast(layer3)isusedtosenddatatoallnodesinthisnetwork.Layer3broadcastingalsosupportsflat,old-fashionedbroadcasting.Broadcastinformationreferstoinformationforthepurposeofallhostsinacertainbroadcastdomain.Thesearecalledwebcasts,andtheyareallthehostbitsareON.

Adataframeorpacketistransmittedtoeachnodeonthelocalnetworksegment(definedbythebroadcastdomain)isbroadcast;duetothedesignofthenetworktopologyandconnectionproblems,orotherreasons,thebroadcastiswithinthenetworksegmentAlargeamountofcopyinganddisseminationofdataframesleadtoadecreaseinnetworkperformanceandevennetworkparalysis.Thisisthebroadcaststorm.

Infact,broadcaststormsmostlyoccurinlocalareanetworksconnectedbyhubsthatarepronetoringconnections.Ifroutersandswitchesareused,becausetheroutersandswitchesaretree-connected,itcaneffectivelypreventbroadcaststorms.Theproduction.

Butonthebackbonenetwork,themainroleoftherouterisrouting.Therouteronthebackbonenetworkmustknowthepathtoalllower-layernetworks.Thisrequiresmaintainingahugeroutingtableandreactingasquicklyaspossibletochangesintheconnectionstate.Thefailureoftherouterwillcauseseriousinformationtransmissionproblems.Insidethecampusnetwork,themainfunctionofroutersistoseparatesubnets.Withthecontinuousexpansionofthenetworkscale,thelocalareanetworkhasevolvedintoacampusnetworkcomposedofmultiplesubnetsconnectedbyhigh-speedbackbonesandrouters.Eachsubnetislogicallyindependent,andtherouteristheonlydevicethatcanseparatethem.Itisresponsibleforpacketforwardingandbroadcastisolationbetweenthesubnets,andtherouterontheborderisresponsiblefortheconnectionwiththeuppernetwork.

RadioDevelopment

In1895,MarconiofItalyandPopovofRussiasimultaneouslyinventedradiowaves.

OnMarch28,1899,Marconisuccessfullysentthefirsttelegram(fromEnglandtoFrance).

OnDecember25,1906,Fanston’sMassachusettsexperimentalstationbroadcastforthefirsttime.Fromtheperspectiveofbroadcastengineeringtechnicalstandards,broadcastingwasborn.Itwasoriginallyanentertainmenttool.

OnAugust31,1920,the8MExperimentalStationinDetroit,USAbroadcastednewsabouttheinitialvictoryoftheGovernorofMichigan.(Theearliestbroadcastnews)

OnOctober27,1920,theKDKAradiostationinPittsburgh,USAwasformallyestablishedasthefirstradiostationwithlegaloperatingrights.Itsbroadcastingmarkstheofficialbirthofthebroadcastingindustry.

OnJanuary24,1923,thefirstradiostationoftheUnitedStatesinChinawasofficiallylaunched,thecallsignwasECO,anditwasthefirstradiostationinChina.

OnDecember30,1940,Yan'anXinhuaBroadcastingStationstartedbroadcasting,callsignXNCR.ThefirstradiostationfoundedbytheCommunistPartyofChina.

Broadcastingadvantages

Auditoryinformation

Broadcastingistransmittedbysound.Thecharmofsoundisthatitnotonlyspreadsinformation,butalsoincorporatestheknowledgeofthespreadingpartyintotheinformation,soastohelpandguidepeopleinunderstandingandreceivingtheinformation.Thehost’sstyleofhostingtheprogramandhisgraspoftheprogramcangreatlyenhancetheappealoftheprogram.Theirre-creationandimprovementofmanuscriptscanhaveagreatimpactontheaudience'sunderstanding,understanding,andacceptanceofinformation.

Withsoundasthecharacteristicofcommunication,itscharmisthat,regardlessoftheageoftheaudience,thelevelofeducation,broadcastingissuitableforallpeople.Broadcastingalsohasmobilityandportability.Peoplecaneasilylearnthelatestinformationfromthebroadcastanytime,anywhere.

Costeconomy

Whetheritisitsownoperatingcostortheaudience'sreceivingcost,thevariousexpensesofbroadcastingarethelowestandthemosteconomical.

Fromtheaudience'spointofview,broadcastingisthecheapestmediumforobtaininginformation.Thishasnothingtodowithpeople'sincreasingconsumptionlevel,becauseeveniftheconsumptionlevelishigh,peoplestillhopetogetthegreatestreturnwiththeleastinvestment.Nowandforaperiodoftimeinthefuture,duetovariousconditions,notallfamiliescanhavecomputers,andnotallpeoplecanhavecomputersonalloccasions.Instead,buyasmallsemiconductororuseothermeanstolistentothebroadcast.,Itisveryeasy.

Fromtheperspectiveofthebroadcaster,thecostofinterviews,production,andtransmissionofradioprogramsisrelativelylowcomparedtoothermedia.Forexample,atelephonecansolvetheproblemofinterviewsandtransmissionofradioprograms,ande-mailsareincreasinglyusedbyradioreportersforinterviews.Althoughthesemethodscannotreplaceface-to-faceinterviews,theycansavevaluabletime,improveworkefficiency,andreducethemanpower,material,andfinancialresourcescausedbyremoteacquisitionofprograms.Ofcourse,thesemethodscanalsobeusedbyothermedia,butwhatbroadcastingusesthesemethodstoobtainisitsuniquewayofexpression-sound.

Fastspeed

Firstofall,thepropagationspeedofbroadcastingisfast.Speed​​isamajoradvantageoftheInternet.Forgeneralinformationprocessing,theInternetisfasterthanbroadcasting.However,formajoreventsandimportantnews,thebroadcastingspeedisfasterthantheInternet.Inotherwords,thespeedofnewsdisseminationofsomethingthatisfollowedbybroadcastreporterscanbealmostequaltothespeedoftheevent.

Thepopularityofmobilephoneshasgreatlyimprovedthetimelinessofbroadcastprograms.Atthesceneofanewsevent,broadcastreportersonlyneedtohaveaphone,theycanwatchsixdirections,listentoalldirections,observe,interview,think,andverballybroadcast,andsendthesignaldirectlytothelivebroadcastroomtokeeptrackoftheprogressofthenewsevent.Reporttotheaudienceinrealtime;atthesametime,itcanalsomakethevarioussoundsonthescene,suchastheconversationofthecharactersandthenaturalsound,directlygotothesky.Broadcastingcanalsobebroadcastlive,andlistenerscanlearnabouttheprogressofnewseventsinrealtime.

Broadcastingdisadvantages

1.Poorretention.Thetransmissioneffectisfleeting,theearsarenotkept,thestorageofinformationispoor,anditisdifficulttoinquireandrecord.

2.Poorselectivity.Lineartransmissionmode,thatis,thebroadcastcontentisarrangedinchronologicalorder.Theaudienceisrestrictedbytheorderoftheprogramandcanonlypassivelyaccepttheestablishedcontent.

3.Thebroadcasthasonlysound,withouttextandimages,andtheaudience'sattentiontothebroadcastinformationiseasilydistracted.

Webcast

Overview

Webcastshouldbesaidtobeakindofnetworkstreamingmedia.ItbuildsabroadcastserverontheInternetsite,runsspecificsoftwareandthenWhentheprogramsarespreadout,weconnecttothesesitesbyinstallingandrunningthebroadcastreceivingsoftwareonourcomputers,andthenwecaneasilylistentothebroadcastprogramsandreadthebroadcastinformation.

Advantages

Today,withtherapiddevelopmentofbroadbandnetworktechnology,networkbroadcastingisrelativelyeasytoimplement,andequipmentinvestmentisrelativelysmall.Ithasinherentadvantages.Mediaallovertheworldarecompetingtodevelopnetworkbroadcasting.Injustafewyearsofdevelopment,accordingtoincompletestatistics,therearenowmorethan3,400Internetvideobroadcastingwebsitesintheworld,andmorethan3,600audiobroadcastingwebsitesusingtheRealPlayersystem;morethan6000newvideo/audioprogramsarebroadcasteveryweek,2300hoursTheaboveon-demandprograms.Fromtheperspectiveofforeignbroadcastcontent,about60%ofaudio/videobroadcastwebsitesbroadcastsinglethematiccontent,andabout40%ofaudio/videobroadcastwebsitesbroadcastcomprehensivecontent.InChina,GuangdongPearlRiverEconomicBroadcastingStationtooktheleadinopeningonlinereal-timebroadcastingonDecember15,1996.CCTVconductedlivebroadcastsonthe"SpringFestivalGala"in2001and2002.

Method

Webcasthastwomainbroadcastforms:livebroadcastandon-demandbroadcast:

ALivebroadcast(Live):Itismainlyusedforreal-timereportsofmajorevents.Itistheonlinetransmissionformoftheprogramsactuallybroadcastbytheradioortelevisionstation.Itsadvantagesarethatitistime-sensitive,vividandpractical,anduserscanobtaininformationinthefirsttime.

BOn-demandAudio/Video:On-demandistomakeprogramsintosegmentsaccordingtothecontent.Youcanselectyourfavoritesegmentsaccordingtothetitleorcategorytolistentoandwatch.Thistypeofplaybackhastheadvantageofsavingresources,andismoreselectiveandtargeted.

Developmenttrend

The21stcenturyisthecenturyoftheInternet.Inthelastfewyearsofthe20thcentury,assoonastheInternetlandedinChina,itemergedasapowerfulmedia,witharapiddevelopmentmomentumandextensivesocialinfluence.InMay1998,theUnitedNationsInformationCommitteeformallyproposedthattheInternethasbecomethefourthmediaafternewspapers,radio,andtelevision.Fromthenon,theInternethasanequalmassmediastatuswiththethreetraditionalmediaofradio,television,andnewspapers.Bytheyear2000,mediawithacertaindegreeofinfluenceinthecountryhad"touchedtheInternet"oneafteranother,sothatthisyearwascalledthe"InternetYear"ofnewsmedia.

Theuseofthethreemajortechnologiesintheinformationage:digitaltechnology,networktechnology,andsatellitetechnologyinthemediahasenabledbroadcastmediatobecomethebiggestbeneficiary,anditalsoenablesbroadcasttoachieve"widespread"inthetruesense.

Ifbroadcastingwantstogetridofthedisadvantagedsituationoftoday’sweakmedia,andseekbigdevelopment,it’sobviouslynotpossibletomakesmallnoises,makepartialadjustments,talkaboutprogramsontheprogram,andjustbroadcastthatbroadcastingisobviouslynotfeasible;anddigitaltechnology,Networktechnologyandsatellitetechnologyprovidesufficienttechnicalsupportforbroadcastingtoundergoaradicaltransformation.Nowadays,broadcastinghasundergonecomprehensivereformsintheaspectsofinterviewing,editing,transmission,production,broadcasting,listening,storage,etc.Thetimeisripeandtheconditionsareready.Moreover,someradiostationsthatareattheforefrontofbroadcastingreformhavemadesuccessfuldemonstrations..

Thesoundqualityofdigitalaudiobroadcastingisaspureasacompactdisc,makingtheentertainmentfunctionofbroadcastingmoreperfect;anddigitalaudiobroadcastinghasstronganti-interferenceability,andthereisnonoisewhenlisteningonthemove,whichisinlinewiththenewfeaturesofpeoplelisteningonthemove.need.Inradiointerviews,editing,production,andbroadcast,digitaltoolsandequipmentcontinuetoappear.InMarch2000,theWorldWideSatellite"AsiaStar"wassuccessfullylaunched.Thecoverageareaof​​onebeamofAsiaStaris140millionkilometers,whichcancoverallofChina.PeoplewithinthescopeoftheWorldWideSatelliteServicecanlistentothebroadcastdirectlyfromthesatellitewithonlyasmallreceiver.The"widespread"ofbroadcastingisnolongeradifficulttask.

Networktechnologyhasopenedupanewtransmissionmethodforbroadcasting-networkbroadcasting,whichhasbuiltasolidplatform.Theconvergenceofbroadcastingandnetworkhasbecomeatrend.

BroadcastingontheInternethasexpandedthescopeoftransmission,andhasalsomadeupfortheinherentdefectsofbroadcasting:lineartransmission,fleeting,unabletosave,unabletoretrieve,andunabletoseetext.NetworkbroadcastingintegratestheadvantagesoftheInternetandaudiobroadcasting,sothatbroadcastingprogramscanbesaved,written,on-demand,retrievedanddownloadedatwill,andtheamountofinformationisgreatlyincreased.Withthedevelopmentofbroadcastingtechnology,networkbroadcastingwilltrulyhighlightthecharacteristicsofpersonalizedservices,providespecificservicesforspecificaudiences,andachieveinteractivityandinteractivebroadcastingwithaudiences.

Overseasdevelopment

Broadcastinghasachievedremarkableresults.Therealizationofthestrategicgoaloffocusingonfrequencymodulation,mediumwaveandshortwaveasasupplementisamajorchangeinthehistoryofourinternationalbroadcasting.InternationalRadiohasadded8newfull-frequencydirectlandingprojectsintheUnitedStates,Canada,Libya,Cambodiaandothercountries,andthereare19full-frequencyradiostationsabroad.Forthefirsttime,theentirefrequencywasimplementedinakeycityintheUnitedStates.Added149hoursofair-to-airbroadcasteveryday,andthetotalcumulativeair-to-airtimereaches700.5hoursperday.

NewChina’sEnglishbroadcastingwasbornduringthewaryears.Foralongperiodoftime,mycountry’sEnglish-languageelectronicmediaismainlybasedontheEnglish-languagechannelofChinaInternationalBroadcastingStation,anddominatesmycountry’sexternalbroadcasting,becominganimportantexternalcommunicationwindowformycountry.Asoftheendof2010,ChinaRadioInternationalwasabletobroadcast2,471hoursofprogramsin61languages​​everyday,coveringmorethan200countriesandregionsaroundtheworld.In2010,itreceived3millionlettersande-mailsfromlistenersfrom161countriesandregions,and3165listenerclubsallovertheworld.ChinaRadioInternationaliscurrentlynotonlyoneofmycountry'slargestoverseasaudiencesandthemostinfluentialpublicityunits,italsoranksamongthetopinternationalradiostationsintheworldintermsofbroadcastlanguage,broadcasttime,transmissionpowerandlisteners'letters.

Definition

Broadcast(original:broadcast)meansthatwhenthepacketistransmittedonacomputernetwork,thedestinationaddressisatransmissionmethodforalldevicesinthenetwork.Infact,the"alldevices"mentionedherearealsolimitedtoarangecalled"broadcastdomain".

Notallcomputernetworkssupportbroadcasting.Forexample,X.25networksandframerelaydonotsupportbroadcasting,andthereisnobroadcasting"intheentireInternet".IPv6alsodoesnotsupportbroadcasting,andthecorrespondingfunctionofbroadcastingisreplacedbymulticast.

Usually,broadcastsarerestrictedtolocalareanetworks,suchasEthernetortokenringnetworks.Becausetheimpactofbroadcastinginthelocalareanetworkismuchsmallerthaninthewideareanetwork.

Broadcastaddress

• EthernetandIPv4networksbothuseall1addressestorepresentbroadcast,respectivelyff:ff:ff:ff:ff:ffand255.255.255.255.

• TokenRingnetworksuseaspecialvalueintheIEEE802.2controldomaintorepresentbroadcast.

Usebroadcastprotocol

• ARP

• DHCP

• NTP(NetworkTimeProtocol)

• Routingdaemon