ITU-T G.728 Annex J (09 1999) (英) Variable bit-r

INTERNATIONALTELECOMMUNICATIONUNIONG.728TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITUAnnexJ(09/99)SERIESG:TRANSMISSIONSYSTEMSANDMEDIA,DIGITALSYSTEMSANDNETWORKSDigitaltransmissionsystems–Terminalequipments–CodingofanaloguesignalsbymethodsotherthanPCMCodingofspeechat16kbit/susinglow-delaycodeexcitedlinearpredictionAnnexJ:Variablebit-rateoperationofLD-CELPmainlyforvoiceband-dataapplicationsinDCMEITU-TRecommendationG.728–AnnexJ(PreviouslyCCITTRecommendation)ITU-TG-SERIESRECOMMENDATIONSTRANSMISSIONSYSTEMSANDMEDIA,DIGITALSYSTEMSANDNETWORKSForfurtherdetails,pleaserefertoITU-TListofRecommendations.INTERNATIONALTELEPHONECONNECTIONSANDCIRCUITSG.100–G.199INTERNATIONALANALOGUECARRIERSYSTEMGENERALCHARACTERISTICSCOMMONTOALLANALOGUECARRIER-TRANSMISSIONSYSTEMSG.200–G.299INDIVIDUALCHARACTERISTICSOFINTERNATIONALCARRIERTELEPHONESYSTEMSONMETALLICLINESG.300–G.399GENERALCHARACTERISTICSOFINTERNATIONALCARRIERTELEPHONESYSTEMSONRADIO-RELAYORSATELLITELINKSANDINTERCONNECTIONWITHMETALLICLINESG.400–G.449COORDINATIONOFRADIOTELEPHONYANDLINETELEPHONYG.450–G.499TESTINGEQUIPMENTSTRANSMISSIONMEDIACHARACTERISTICSDIGITALTRANSMISSIONSYSTEMSTERMINALEQUIPMENTSG.700–G.799GeneralG.700–G.709CodingofanaloguesignalsbypulsecodemodulationG.710–G.719CodingofanaloguesignalsbymethodsotherthanPCMG.720–G.729PrincipalcharacteristicsofprimarymultiplexequipmentG.730–G.739PrincipalcharacteristicsofsecondordermultiplexequipmentG.740–G.749PrincipalcharacteristicsofhigherordermultiplexequipmentG.750–G.759PrincipalcharacteristicsoftranscoderanddigitalmultiplicationequipmentG.760–G.769Operations,administrationandmaintenancefeaturesoftransmissionequipmentG.770–G.779PrincipalcharacteristicsofmultiplexingequipmentforthesynchronousdigitalhierarchyG.780–G.789OtherterminalequipmentG.790–G.799DIGITALNETWORKSG.800–G.899DIGITALSECTIONSANDDIGITALLINESYSTEMG.900–G.999RecommendationG.728/AnnexJ(09/99)iITU-TRECOMMENDATIONG.728CODINGOFSPEECHAT16kbit/sUSINGLOW-DELAYCODEEXCITEDLINEARPREDICTIONANNEXJVariablebit-rateoperationofLD-CELPmainlyforvoiceband-dataapplicationsinDCMESummaryAnnexJtoRecommendationG.728definesa40kbit/sextensionoptimizedforvoicebanddatasignalsoftheexistingAnnexG/G.728–16kbit/sfixedpointspecification.ThemaindifferencebetweenthecodecdescribedherebyandthecodecdescribedinAnnexG/G.728istheapplicationofaTrellis-CodedQuantization(TCQ)approachtocodebooksearch.TheTCQapproachreplacestheanalysis-by-synthesisapproachtocodebooksearchofRecommendationG.728onlyinvoicebanddata(VBD)mode.ThebackwardadaptationofthepredictorachievedinVBDmodeisalmostidenticaltothebackwardadaptationachievedinspeechmode(RecommendationG.728).Additionally,thesameadaptationcycleisusedforbothspeechmode(RecommendationG.728)andVBDmode.Inspeechmode,the40kbit/srevertstotheLD-CELPofRecommendationG.728.ThisannexincludesanelectronicattachementcontainingtestvectorsforimplementationverificationofAnnexJ/G.728.SourceAnnexJtoRecommendationG.728,waspreparedbyITU-TStudyGroup16(1997-2000)andwasapprovedundertheWTSCResolutionNo.1procedureon30September1999.iiRecommendationG.728/AnnexJ(09/99)FOREWORDITU(InternationalTelecommunicationUnion)istheUnitedNationsSpecializedAgencyinthefieldoftelecommunications.TheITUTelecommunicationStandardizationSector(ITU-T)isapermanentorganoftheITU.TheITU-Tisresponsibleforstudyingtechnical,operatingandtariffquestionsandissuingRecommendationsonthemwithaviewtostandardizingtelecommunicationsonaworldwidebasis.TheWorldTelecommunicationStandardizationConference(WTSC),whichmeetseveryfouryears,establishesthetopicsforstudybytheITU-TStudyGroupswhich,intheirturn,produceRecommendationsonthesetopics.TheapprovalofRecommendationsbytheMembersoftheITU-TiscoveredbytheprocedurelaiddowninWTSCResolutionNo.1.InsomeareasofinformationtechnologywhichfallwithinITU-T’spurview,thenecessarystandardsarepreparedonacollaborativebasiswithISOandIEC.NOTEInthisRecommendationthetermrecognizedoperatingagency(ROA)includesanyindividual,company,corporationorgovernmentalorganizationthatoperatesapubliccorrespondenceservice.ThetermsAdministration,ROAandpubliccorrespondencearedefinedintheConstitutionoftheITU(Geneva,1992).INTELLECTUALPROPERTYRIGHTSTheITUdrawsattentiontothepossibilitythatthepracticeorimplementationofthisRecommendationmayinvolvetheuseofaclaimedIntellectualPropertyRight.TheITUtakesnopositionconcerningtheevidence,validityorapplicabilityofclaimedIntellectualPropertyRights,whetherassertedbyITUmembersorothersoutsideoftheRecommendationdevelopmentprocess.AsofthedateofapprovalofthisRecommendation,theITUhadnotreceivednoticeofintellectualproperty,protectedbypatents,whichmayberequiredtoimplementthisRecommendation.However,implementorsarecautionedthatthismaynotrepresentthelatestinformationandarethereforestronglyurgedtoconsulttheTSBpatentdatabase.
ITU2000Allrightsreserved.Nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromtheITU.RecommendationG.728/AnnexJ(09/99)iiiCONTENTSPageJ.1Scope........................................................