ETSI EN 300 961 V8.1.1 (2000-11)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Digital cellular telecommunications system (Phase 2+) (GSM); Full rate speech; Transcoding (GSM 06.10 version 8.1.1 Release 1999)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:EN 300 961 Version 8.1.1SIST EN 300 961 V8.1.1:2003en01-december-2003SIST EN 300 961 V8.1.1:2003SLOVENSKI
STANDARD



SIST EN 300 961 V8.1.1:2003



ETSIEN300961V8.1.1(2000-11)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);Fullratespeech;Transcoding(GSM06.10version8.1.1Release1999)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)2(GSM06.10version8.1.1Release1999)ReferenceREN/SMG-110610Q8R1KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)ETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:+33492944200Fax:+33493654716SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88ImportantnoticeIndividualcopiesofthepresentdocumentcanbedownloadedfrom:http://www.etsi.orgThepresentdocumentmaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.Usersofthepresentdocumentshouldbeawarethatthedocumentmaybesubjecttorevisionorchangeofstatus.InformationonthecurrentstatusofthisandotherETSIdocumentsisavailableathttp://www.etsi.org/tb/status/Ifyoufinderrorsinthepresentdocument,sendyourcommentto:editor@etsi.frCopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)3(GSM06.10version8.1.1Release1999)ContentsIntellectualPropertyRights.6Foreword.61Scope.81.1References.81.1.1Abbreviations.91.2Outlinedescription.91.3Functionaldescriptionofaudioparts.91.4PCMFormatconversion.101.5PrinciplesoftheRPE-LTPencoder.101.6PrinciplesoftheRPE-LTPdecoder.111.7Sequenceandsubjectiveimportanceofencodedparameters.112Transmissioncharacteristics.142.1Performancecharacteristicsoftheanalogue/digitalinterfaces.142.2Transcoderdelay.143FunctionaldescriptionoftheRPE-LTPcodec.143.1FunctionaldescriptionoftheRPE-LTPencoder.143.1.1Offsetcompensation.153.1.2Pre-emphasis.153.1.3Segmentation.153.1.4Autocorrelation.163.1.5SchurRecursion.163.1.6TransformationofreflectioncoefficientstoLog.-AreaRatios.163.1.7QuantizationandcodingofLog.-AreaRatios.163.1.8DecodingofthequantizedLog.-AreaRatios.173.1.9InterpolationofLog.-AreaRatios.173.1.10TransformationofLog.-AreaRatiosintoreflectioncoefficients.173.1.11Shorttermanalysisfiltering.173.1.12Sub-segmentation.183.1.13CalculationoftheLTPparameters.183.1.14Coding/DecodingoftheLTPlags.183.1.15Coding/DecodingoftheLTPgains.193.1.16Longtermanalysisfiltering.193.1.17Longtermsynthesisfiltering.193.1.18WeightingFilter.203.1.19AdaptivesampleratedecimationbyRPEgridselection.203.1.20APCMquantizationoftheselectedRPEsequence.203.1.21APCMinversequantization.213.1.22RPEgridpositioning.223.2Decoder.223.2.1RPEdecodingclause.223.2.2LongTermPredictionclause.223.2.3Shorttermsynthesisfilteringclause.223.2.4Post-processing.224Codechoming.264.1Functionaldescription.264.2Definitions.264.3Encoderhoming.274.4Decoderhoming.274.5Encoderhomestate.284.6Decoderhomestate.285ComputationaldetailsoftheRPE-LTPcodec.285.1Datarepresentationandarithmeticoperations.285.2FixedpointimplementationoftheRPE-LTPcoder.30SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)4(GSM06.10version8.1.1Release1999)5.2.0Scalingoftheinputvariable.315.2.1Downscalingoftheinputsignal.315.2.2Offsetcompensation.315.2.3Pre-emphasis.315.2.4Autocorrelation.325.2.5Computationofthereflectioncoefficients.325.2.6TransformationofreflectioncoefficientstoLog.-AreaRatios.335.2.7QuantizationandcodingoftheLog.-AreaRatios.345.2.8DecodingofthecodedLog.-AreaRatios.345.2.9Computationofthequantizedreflectioncoefficients.345.2.9.1InterpolationoftheLARpp[1.8]togettheLARp[1.8].345.2.9.2Computationoftherp[1.8]fromtheinterpolatedLARp[1.8].355.2.10Shorttermanalysisfiltering.355.2.11CalculationoftheLTPparameters.365.2.12Longtermanalysisfiltering.375.2.13Weightingfilter.375.2.14RPEgridselection.385.2.15APCMquantizationoftheselectedRPEsequence.385.2.16APCMinversequantization.395.2.17RPEgridpositioning.395.2.18Updateofthereconstructedshorttermresidualsignaldp[-120.-1].405.3FixedpointimplementationoftheRPE-LTPdecoder.405.3.1RPEdecodingclause.405.3.2Longtermsynthesisfiltering.405.3.3Computationofthedecodedreflectioncoefficients.415.3.4Shorttermsynthesisfilteringclause.415.3.5De-emphasisfiltering.425.3.6Upscalingoftheoutputsignal.425.3.7Truncationoftheoutputvariable.425.4TablesusedinthefixedpointimplementationoftheRPE-LTPcoderanddecoder.436Digitaltestsequences.446.1Inputandoutputsignals.446.2Configurationfortheapplicationofthetestsequences.446.2.1Configuration1(encoderonly).456.2.2Configuration2(decoderonly).456.3Testsequences.466.3.1Testsequencesforconfiguration1.466.3.2Testsequencesforconfiguration2.466.3.3AdditionalTestsequencesforCodecHoming.506.3.3.1Codechomingframes.506.3.3.2Sequenceforanextensivetestofthedecoderhoming.506.3.3.3Sequencesforfindingthe20msframingoftheGSMfullratespeechencoder.506.3.3.4Formatsandsizesofthesynchronizationsequences.51AnnexA(informative):Codecperformance.53A.1PerformanceoftheRPE-LTP.53A.1.1Introduction.53A.1.2Speechperformance.53A.1.2.1Singleencoding.53A.1.2.2Speechperformancewheninterconnectedwithcodingsystemsonananaloguebasis.54A.1.2.2.1Performancewith32kbit/sADPCM(G.721,supersededbyG.726).54A.1.2.2.2PerformancewithanotherRPE-LTPcodec.54A.1.2.2.3PerformancewithencodingotherthanRPE-LTPand32kbit/sADPCM(G.721,supersededbyG.726).54A.1.3Non-speechperformance.55A.1.3.1Performancewithsinglesinewaves.55A.1.3.2PerformancewithDTMFtones.55A.1.3.3Performancewithinformationtones.55A.1.3.4Performancewithvoice-banddata.55A.1.4Delay.55A.1.5Bibliography.57SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)5(GSM06.10version8.1.1Release1999)A.2Subjectiverelevanceofthespeechcoderoutputbits.57A.3Formatfortestsequencedistribution.59A.3.1Typeoffilesprovided.59A.3.2Fileformatdescription.60AnnexB(informative):Testsequencedisks.62AnnexC(informative):ChangeRequestHistory.63History.64SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)6(GSM06.10version8.1.1Release1999)IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinETSISR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinETSISR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbyETSITechnicalCommitteeSpecialMobileGroup(SMG).Thepresentdocumentspecifiesthefullratespeechtranscodingwithinthedigitalcellulartelecommunicationssystem.NOTE:ThepresentdocumentisareproductionofrecommendationT/L/03/11"13kbit/sRegularPulseExcitation-LongTermPrediction-LinearPredictiveCoderforuseinthedigitalcellulartelecommunicationssystem".Archiveen_300961v080101p0.ZIPwhichaccompaniesthepresentdocument,containstestsequences,asdescribedinclause6andannexA.3.Thearchivecontainsthefollowing:Disk1.zipAnnexB:TestsequencesfortheGSMFullRatespeechcodec;TestsequencesSEQ01.xxxtoSEQ05.xxx.(Disk1.zipcontainsLHAcompressedfiles.)Disk2.zipAnnexB:TestsequencesfortheGSMFullRatespeechcodecwithhomingframes;TestsequencesSEQ01H.*toSEQ02H.*.Disk3.zipAnnexB:TestsequencesfortheGSMFullRatespeechcodecwithhomingframes;TestsequencesSEQ03H.*toSYNC159.COD.Disk4.zipAnnexB:8bitA-lawtestsequencesfortheGSMFullRatespeechcodecwithandwithouthomingframes(Disk4.zipcontainsself-extractingfiles).Disk5.zipAnnexB:8bitµ-lawtestsequencesfortheGSMFullRatespeechcodecwithandwithouthomingframes(Disk5.zipcontainsself-extractingfiles).SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)7(GSM06.10version8.1.1Release1999)ThecontentsofthepresentdocumentissubjecttocontinuingworkwithinSMGandmaychangefollowingformalSMGapproval.ShouldSMGmodifythecontentsofthepresentdocumentitwillbere-releasedwithanidentifyingchangeofreleasedateandanincreaseinversionnumberasfollows:Version8.x.ywhere:8indicatesRelease1999ofGSMPhase2+.xtheseconddigitisincrementedforallchangesofsubstance,i.e.technicalenhancements,corrections,updates,etc.ythethirddigitisincrementedwheneditorialonlychangeshavebeenincorporatedinthespecification.NationaltranspositiondatesDateofadoptionofthisEN:24November2000DateoflatestannouncementofthisEN(doa):28February2001DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):31August2001DateofwithdrawalofanyconflictingNationalStandard(dow):31August2001SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)8(GSM06.10version8.1.1Release1999)1ScopeThetranscodingprocedurespecifiedinthepresentdocumentisapplicableforthefull-rateTrafficChannel(TCH)inthedigitalcellulartelecommunicationssystem.Theuseofthistranscodingschemeforotherapplicationshasnotbeenconsidered.InGSM06.01,areferenceconfigurationforthespeechtransmissionchainofthedigitalcellulartelecommunicationssystemisshown.Accordingtothisreferenceconfiguration,thespeechencodertakesitsinputasa13bituniformPCMsignaleitherfromtheaudiopartofthemobilestationoronthenetworkside,fromthePSTNviaan8bit/A-orµ-law(PCS1900)to13bituniformPCMconversion.TheencodedspeechattheoutputofthespeechencoderisdeliveredtoachannelencoderunitwhichisspecifiedinGSM05.03.Inthereceivedirection,theinverseoperationstakeplace.Thepresentdocumentdescribesthedetailedmappingbetweeninputblocksof160speechsamplesin13bituniformPCMformattoencodedblocksof260bitsandfromencodedblocksof260bitstooutputblocksof160reconstructedspeechsamples.Thesamplingrateis8000sample/sleadingtoanaveragebitratefortheencodedbitstreamof13kbit/s.Thecodingschemeistheso-calledRegularPulseExcitation-LongTermprediction-LinearPredictiveCoder,here-afterreferredtoasRPE-LTP.ThepresentdocumentalsospecifiestheconversionbetweenA-andµ-law(PCS1900)PCMand13bituniformPCM.Performancerequirementsfortheaudioinputandoutputpartsareincludedonlytotheextentthattheyaffectthetranscoderperformance.Thepresentdocumentalsodescribesthecodecdowntothebitlevel,thusenablingtheverificationofcompliancetothepresentdocumenttoahighdegreeofconfidencebyuseofasetofdigitaltestsequences.Thesetestsequencesaredescribedandarecontainedinarchiveen_300961v080101p0.ZIPwhichaccompaniesthepresentdocument.1.1ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,thelatestversionapplies.• Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.• ForthisRelease1999document,referencestoGSMdocumentsareforRelease1999versions(version8.x.y).[1]GSM01.04:"Digitalcellulartelecommunicationssystem(Phase2+);Abbreviationsandacronyms".[2]GSM05.03:"Digitalcellulartelecommunicationssystem(Phase2+);Channelcoding".[3]GSM06.01:"Digitalcellulartelecommunicationssystem(Phase2+);Fullratespeech;Processingfunctions".[4]GSM11.10:"Digitalcellulartelecommunicationssystem(Phase2+);MobileStation(MS)conformityspecification".[5]ETS300085:"IntegratedServicesDigitalNetwork(ISDN);3,1kHztelephonyteleservice;Attachmentrequirementsforhandsetterminals(CandidateNET33)".[6]ITU-TRecommendationG.711:"Pulsecodemodulation(PCM)ofvoicefrequencies".[7]ITU-TRecommendationG.712:"Transmissionperformancecharacteristicsofpulsecodemodulation".SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)9(GSM06.10version8.1.1Release1999)[8]ITU-TRecommendationG.726:"40,32,24,16kbit/sadaptivedifferentialpulsecodemodulation(ADPCM)".[9]ITU-TRecommendationQ.35:"Technicalcharacteristicsoftonesforthetelephoneservice".[10]ITU-TRecommendationV.21:"300bitspersecondduplexmodemstandardizedforuseinthegeneralswitchedtelephonenetwork".[11]ITU-TRecommendationV.23:"600/1200-bandmodemstandardizedforuseinthegeneralswitchedtelephonenetwork".[12]GSM06.32:"Digitalcellulartelecommunicationssystem(Phase2+);VoiceActivityDetector(VAD)".1.1.1AbbreviationsAbbreviationsusedinthepresentdocumentarelistedinGSM01.04.1.2OutlinedescriptionThepresentdocumentisstructuredasfollows:Subclause1.3containsafunctionaldescriptionoftheaudiopartsincludingtheA/DandD/Afunctions.Subclause1.4describestheconversionbetween13bituniformand8bitA-lawsamples.Subclauses1.5and1.6presentasimplifieddescriptionoftheprinciplesoftheRPE-LTPencodinganddecodingprocessrespectively.Inclause1.7,thesequenceandsubjectiveimportanceofencodedparametersaregiven.Clause2dealswiththetransmissioncharacteristicsoftheaudiopartsthatarerelevantfortheperformanceoftheRPE-LTPcodec.SometransmissioncharacteristicsoftheRPE-LTPcodecarealsospecifiedinclause2.Clause3presentsthefunctionaldescriptionoftheRPE-LTPcodinganddecodingprocedures,whereasclause4describesthecomputationaldetailsofthealgorithm.ProceduresfortheverificationofthecorrectfunctioningoftheRPE-LTParedescribedinclause5.PerformanceandnetworkaspectsoftheRPE-LTPcodecarecontainedinannexA.1.3FunctionaldescriptionofaudiopartsTheanalogue-to-digitalanddigital-to-analogueconversionwillinprinciplecomprisethefollowingelements:1)Analoguetouniformdigital:-microphone;-inputleveladjustmentdevice;-inputanti-aliasingfilter;-sample-holddevicesamplingat8kHz;-analogue-to-uniformdigitalconversionto13bitsrepresentation.Theuniformformatshallberepresentedintwo'scomplement.2)Uniformdigitaltoanalogue:-conversionfrom13bit/8kHzuniformPCMtoanalogue;-aholddevice;-reconstructionfilterincludingx/sinxcorrection;-outputleveladjustmentdevice;SIST EN 300 961 V8.1.1:2003



ETSIETSIEN300961V8.1.1(2000-11)10(GSM06.10version8.1.1Release1999)-earphoneorloudspeaker.Intheterminalequipment,theA/Dfunctionmaybeachievedeither:-bydirectconversionto13bituniformPCMformat;-orbyconversionto8bit/A-orµ-law(PCS1900)compandedformat,basedonastandardA-orµ-law(PCS1900)codec/filteraccordingtoITU-TRecommendationG.711/714,followedbythe8-bitto13-bitconversionaccordingtotheprocedurespecifiedinclause1.4.FortheD/Aoperation,theinverseoperationstakeplace.InthelattercaseitshouldbenotedthatthespecificationsinITU-TrecommendationG.714(supersededbyG.712)areconcernedwithPCMequipmentlocatedinthecentralpartsofthenetwork.Whenusedintheterminalequipment,thepresentdocumentdoesnotonitsownensuresufficientout-of-bandattenuation.Thespecificationofout-of-bandsignalsisdefinedinclause2betweentheacousticsignalandthedigitalinterfacetotakeintoaccountthatthefilteringintheterminalcanbeachievedbothbyelectronicandacousticaldesign.1.4PCMFormatconversionTheconversionbetween8bitA-orµ-law(PCS1900)compandedformatandthe13-bituniformformatshallbeasdefinedinITU-TRecommendationG.721(supersededbyG.726),clause4.2.1,sub-blockEXPANDandclause4.2.7,sub-blockCOMPRESS.TheparameterLAW=1shouldbeusedforA-lawandLAW=0shouldbeusedforµ-law(PCS1900).1.5PrinciplesoftheRPE-LTPencoderAsimplifiedblockdiagramoftheRPE-LTPencoderisshowninfigure1.1.Inthisdiagramthecodingandquantizationfunctionsarenotshownexplicitly.Theinputspeechframe,consistingof160signalsamples(uniform13bitPCMsamples),isfirstpre-processedtoproduceanoffset-freesignal,whichisthensubjectedtoafirstorderpre-emphasisfilter.The160samplesobtainedarethenanalysedtodeterminethecoefficientsfortheshorttermanalysisfilter(LPCanalysis).Theseparametersarethenusedforthefilteringofthesame160samples.Theresultis160samplesoftheshorttermresidualsignal.Thefilterparameters,termedreflectioncoefficients,aretransformedtolog.arearatios,LARs,beforetransmission.Forthefollowingoperations,thespeechframeisdividedinto4sub-frameswith40samplesoftheshorttermresidualsignalineach.Eachsub-frameisprocessedblockwisebythesubsequentfunctionalelements.Beforetheprocessingofeachsub-blockof40shorttermresidualsamples,theparametersofthelongtermanalysisfilter,theLTPlagandtheLTPgain,areestimatedandupdatedintheLTPanalysisblock,onthebasisofthecurrentsub-blockofthepresentandastoredsequenceofthe120previousreconstructedshorttermresidualsamples.Ablockof40longtermresidualsignalsamplesisobtainedbysubtracting40estimatesoftheshorttermresidualsignalfromtheshorttermresidualsignalitself.Theresultingblockof40longtermresidualsamplesisfedtotheRegularPulseExcitationanalysiswhichperformsthebasiccompressionfunctionofthealgorithm.AsaresultoftheRPE-analysis,theblockof40inputlongtermresidualsamplesarerepresentedbyoneof4candidatesub-sequencesof13pulseseach.ThesubsequenceselectedisidentifiedbytheRPEgridposition(M).The13RPEpulsesareencodedusingAdaptivePulseCodeModulation(APCM)withestimationofthesub-blockamplitudewhich
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