ITU-T J.11 (11 1988)(英) Hypothetical reference cir

INTERNATIONALTELECOMMUNICATIONUNION)454*TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU4%,%6)3)/.!.$3/5.$42!.3-)33)/.(90/4(%4)#!,2%&%2%.#%#)2#5)43&/23/5.$02/'2!--%42!.3-)33)/.3)454Recommendation*(ExtractfromtheLUEOOK)NOTES1ITU-TRecommendationJ.11waspublishedinFascicleIII.6oftheBlueBook.ThisfileisanextractfromtheBlueBook.WhilethepresentationandlayoutofthetextmightbeslightlydifferentfromtheBlueBookversion,thecontentsofthefileareidenticaltotheBlueBookversionandcopyrightconditionsremainunchanged(seebelow).2InthisRecommendation,theexpression“Administration”isusedforconcisenesstoindicatebothatelecommunicationadministrationandarecognizedoperatingagency.ITU1988,1993Allrightsreserved.Nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromtheITU.FascicleIII.6-Rec.J.111RecommendationJ.11FascicleIII.6-Rec.J.11HYPOTHETICALREFERENCECIRCUITSFORSOUND-PROGRAMMETRANSMISSIONS1),2),3)(Geneva,1972;amendedatGeneva,1976,andatMelbourne,1988)Terrestrialsystemsandsystemsinthefixed-satelliteserviceTheCCITT,considering(a)thatthereisaneedtodefineahypotheticalreferencecircuittoenabledesignperformancestandardstobeset;(b)thatthehypotheticalreferencecircuitshouldallowthedifferenttypesofsound-programmecircuitstobecomparedonacommonbasis,unanimouslyrecommends(1)thatthemainfeaturesofthehypotheticalreferencecircuitforsound-programmetransmissionsoveraterrestrialsystem(showninaFigure1/J.11),whichmaybeprovidedbyeitherradioorcable,shouldbe:-theoveralllengthbetweenaudiopoints(BandC)is2500km,-twointermediateaudiopoints(MandM’)whichdividethecircuitintothreesectionsofequallengths,-thethreesectionswhicharelinedupindividuallyandtheninter-connectedwithoutanyformofoveralladjustmentorcorrection;(2)thatthemainfeaturesofthehypotheticalreferencecircuitforsound-programmetransmissionsoverasysteminthefixed-satelliteservice(showninFigure2/J.11)shouldbe:-onelink:earthstation–satellite–earthstation,-onepairofmodulationanddemodulationequipmentsfortranslationfrombasebandtoradiofrequency,andfromradiofrequencytobaseband,respectively._______________1)ThisRecommendationcorrespondstoCCIRRecommendation502.2)ThehypotheticalreferencecircuitsdefinedinthisRecommendationshouldapplyforbothanalogueanddigitalsystems.3)FormaintenancepurposestheremaybeaneedtodefineothercircuitsofwhichanillustrationisshowninAnnexAofthisRecommendation.2FascicleIII.6-Rec.J.11ANNEXA(toRecommendationJ.11)Illustrationofaninternationalsound-programmeconnectionFigureA-1/J.11illustratesatypicalinternationalsound-programmeconnectioninwhich:-pointA,tobeconsideredasthesendingendoftheinternationalsound-programmeconnection,maybethepointatwhichtheprogrammeoriginates(studiooroutsidelocation);-pointD,tobeconsideredasthereceivingendoftheinternationalsound-programmeconnection,maybeaprogramme-mixingorrecordingcentreorabroadcastingstation;-thelocalsound-programmecircuitABconnectspointAtothesendingterminalstation,pointB,oftheinternationalsound-programmecircuitBC;-thelocalsound-programmecircuitCDconnectspointC,thereceivingterminalstationoftheinternationalsound-programmecircuitBCtothepointD.Thehypotheticalreferencecircuitmustnotbeconsideredidenticaltoanyofthesound-programmecircuitsillustratedaboveortothosedefinedformaintenancepurposesin[1].However,someofthesecircuitsmaydisplaythesamestructureasthehypotheticalreferencecircuit.Suchtypesofcircuitsare:-aninternationalsound-programmeconnectioncomprisingthreeaudiosections;-asinglesound-programmecircuitmadeupofthreeaudiosections.Inthiscase,theperformancestandardssetforthehypotheticalreferencecircuitmaybeappliedtothesecircuits.FascicleIII.6-Rec.J.113Reference[1]Maintenance;internationalsound-programmeandtelevisiontransmissioncircuits.RecommendationsoftheNSeries.FascicleIV.3.