ITU-T J.27 (06 1990)(英) Signals for the alignment…

INTERNATIONALTELECOMMUNICATIONUNION)454*EX#-44 TELECOMMUNICATION(06/90)STANDARDIZATIONSECTOROFITU4%,%6)3)/.!.$3/5.$42!.3-)33)/.3)'.!,3&/24(%!,)'.-%.4/&).4%2.!4)/.!,3/5.$02/'2!--%#/..%#4)/.3)454Recommendation*(FormerlyRecommendationITU-RCMTT.661)FOREWORDTheITUTelecommunicationStandardizationSector(ITU-T)isapermanentorganoftheInternationalTelecom-municationUnion.TheITU-Tisresponsibleforstudyingtechnical,operatingandtariffquestionsandissuingRecommendationsonthemwithaviewtostandardizingtelecommunicationsonaworldwidebasis.TheWorldTelecommunicationStandardizationConference(WTSC),whichmeetseveryfouryears,establishedthetopicsforstudybytheITU-TStudyGroupswhich,intheirturn,produceRecommendationsonthesetopics.ITU-TRecommendationJ.27(formerlyRecommendationITU-RCMTT.661)waselaboratedbytheformerITU-RStudyGroupCMTT.SeeNote1below.___________________NOTES1AsaconsequenceofareformprocesswithintheInternationalTelecommunicationUnion(ITU),theCCITTceasedtoexistasof28February1993.Initsplace,theITUTelecommunicationStandardizationSector(ITU-T)wascreatedasof1March1993.Similarly,inthisreformprocess,theCCIRandtheIFRBhavebeenreplacedbytheRadiocommunicationSector(ITU-R).ConformingtoajointdecisionbytheWorldTelecommunicationStandardizationConference(Helsinki,March1993)andtheRadiocommunicationAssembly(Geneva,November1993),theITU-RStudyGroupCMTTwastransferredtoITU-TasStudyGroup9,exceptforthesatellitenewsgathering(SNG)studyareawhichwastransferredtoITU-RStudyGroup4.2InthisRecommendation,theexpression“Administration”isusedforconcisenesstoindicatebothatelecommunicationadministrationandarecognizedoperatingagency.ITU1990Allrightsreserved.Nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromtheITU.RecommendationJ.27(06/90)1RecommendationJ.271)RecommendationJ.27(06/90)SIGNALSFORTHEALIGNMENTOFINTERNATIONALSOUND-PROGRAMMECONNECTIONS(1986;revised1990)TheCCIR,CONSIDERING(a)thatRecommendation645definesthreetestsignalstobeusedoninternationalsound-programmeconnections;(b)thatnolevelinformationcanbederivedfromasingle-leveltestsignalconcerningitsrelationshiptothelevelsdefinedinRecommendation645;(c)thatmanyimpairmentsininternationalprogrammeexchangescanbetracedtomisinterpretationsofthesingle-leveltestsignals;(d)thatthetestsignalsinRecommendation645couldbeusedtoalignsound-programmecommentaryconnectionsontheswitchedtelephonenetworkwhichcannotaccommodatehighlevelsinusoidaltestsignals,UNANIMOUSLYRECOMMENDSthatinternationalsound-programmeconnectionsshouldbeidentifiedandalignedusingthedefinitionsin§1,thetestsignalformatin§2andthemeasurementmethodsin§3ofthisRecommendation.1.Definitions1.1SourceidentificationAnannouncementshouldbeusedtoidentifytheoriginatingpointofthetestsignalsandshouldbepreferablyasshortaspossible.Itissuggestedthatsuchanannouncementcontainatleastthefollowinginformation:–nameoforiginatingorganization,–location,–country.Thesound-programmesignalshouldbecontrolledbythesendingbroadcastersothattheamplitudesofthepeaksonlyrarelyexceedthepeakamplitudeofthepermittedmaximum(sine-wavetest)signal.1.2Testsignalandleveldefinitions1.2.1Alignmentsignal(AS)Sine-wavesignalat1kHz2)atalevelof0dBm0s,whichisusedtoaligntheinternationalsound-programmeconnection.1.2.2Measurementsignal(MS)Sine-wavesignalat1kHz2)atalevel12dBbelowthealignmentsignallevel,whichshouldbeusedforlong-termmeasurementsandmeasurementsatallfrequencies.1.2.3Permittedmaximumsignal(PMS)Sine-wavesignalat1kHz2),9dBabovethealignmentsignallevel,equivalenttothepermittedmaximumprogramme-signallevel._______________1)FormerlyRecommendationITU-RCMTT.661.2)Thisfrequencyisnominal,and1020HzrecommendedbyCCITTRecommendationO.33maybeused.2RecommendationJ.27(06/90)2.Testsignalformat2.1Athree-levelsinusoidaltestsignalatareferencefrequencyof1kHz3)shouldbeusedtocheckthealignmentofinternationalsound-programmeconnections.ThesethreelevelsshouldbecombinedwiththesourceidentificationandberepeatedcyclicallyasspecifiedintheformatshowninFig.1formonophonicandstereophonicconnections.d01-scFIGURE1/661-1...[D01]_______________3)Thisfrequencyisnominal,and1020HzrecommendedbyCCITTRecommendationO.33maybeused.RecommendationJ.27(06/90)32.2Thesetestsignalsshouldnotbeconnecteddirectlytotheswitchedtelephonenetworkasexcessivechannelloadingorcrosstalkintootherchannelsmaybeproduced.2.3Someorganizationsmaynothaveautomaticallygeneratedtestlevelsasdefinedin§2.1.Inthesecases,thealignmentlevelof0dBm0sat1kHz(seeNote)shouldbeusedforthealignmentofinternationalsound-programmeconnections.Note–Thisfrequencyisnominal,and1020HzrecommendedbyCCITTRecommendationO.33maybeused.3.MeasurementmethodsThefundamentalconceptofthetestsignalsdefinedinthisRecommendationistoprovideorganizationswithaccurateandwell-definedlevels[Thiele,1984].Theselevelsareintendedtoproviderapididentificationoflevelerrorsaswellastoallowoperationalpersonnelsufficienttimetomakethenecessaryleveladjustmentsattheappropriatepointsintheinternationalsound-programmeconnec