外文翻译----30mhz-3000mhz 地面数字音频广播系统技术规范

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1、附录一、英文原文Specificationof30-3000MHzTerrestrialDigitalAudioBroadcastingSystemTheprincipalmethodofuseraccesstotheservicecomponentscarriedintheMultiplexisbyselectingaservice.Severalservicesmaybeaccessiblewithinoneensemble,andeachservicecontainsoneormoreservic

2、ecomponents.However,dedicatedDABdataterminalsmaysearchforandselecttheUserApplication(s)theyareabletoprocessautomaticallyorafteruserselection.Theessentialservicecomponentofaserviceiscalledtheprimaryservicecomponent.Normallythiswouldcarrytheaudio(programme

3、servicecomponent),butdataservicecomponentscanbeprimaryaswell.Allotherservicecomponentsareoptionalandarecalledsecondaryservicecomponents.Thesub-channelorganizationdefinesthepositionandsizeofthesub-channelsintheCIFandtheerrorprotectionemployed.ItiscodedinE

4、xtensions1and14ofFIGtype0.Upto64sub-channelsmaybeaddressedinamultiplexusingasub-channelIdentifierwhichtakesvalues0to63.Thevaluesarenotrelatedtothesub-channelpositionintheMSC.Theserviceorganizationdefinestheservicesandservicecomponentscarriedintheensemble

5、.ItiscodedintheExtensions2,3,4and8ofFIGtype0.EachserviceshallbeidentifiedbyaServiceIdentifierwhich,whenusedinconjunctionwithanExtendedCountryCode,isuniqueworld-wide.Eachservicecomponentshallbeuniquelyidentifiedwithintheensemble.Whenaservicecomponentistra

6、nsportedintheMSCinStreammode,thebasicserviceorganizationinformationiscodedinFIG0/2.Servicecomponents,carriedinthePacketmode,requireadditionalsignallingofthesub-channelandpacketaddress.Extension3isusedforthispurpose.Also,whenservicecomponentsarescrambled,

7、theConditionalAccessOrganizationfieldissignalledinExtension3,fordatainpacketmode,andinExtension4fordatacarriedinthestreammodeorintheFIC.TheExtension8providesinformationtolinktogethertheservicecomponentdescriptionthatisvalidwithintheensembletoaservicecomp

8、onentdescriptionthatisvalidinotherensembles.TheensembleinformationcontainsSIandcontrolmechanismswhicharecommontoallservicescontainedintheensemble.ItisspecificallyusedtoprovideanalarmflagandCIFcounter(24msincrements)forusew