ITU-T G.168Digital network echo cancellers

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1、EnhancedITU-TG.168EchoCancellationThisdocumentdescribesthethird-partyG.168extendedechocanceller(EC)usedinCiscogatewayswithCiscoIOSRelease12.2(13)ZH.TheextendedECusestheCiscovoicedigitalsignalprocessor(DSP)codebase(DSPWare).TheEnhancedITU-TG.168EchoCancellationfeatu

2、reprovidesanalternativetothedefaultCisco-proprietaryG.165EC.ThenewextendedECprovidesimprovedperformancefortrunkinggatewayapplicationsandprovidesaconfigurabletaillengththatsupportsupto64msofechocancellation.TheextendedECoffersthefollowingimprovementsovertheCiscodefa

3、ultEC:•ComplieswiththeITU-TG.168(2000)standardinadditiontomaintainingsupportfortheoldITU-TG.165standard.•Increasestheconfigurabletaillengthfromamaximumof32mstoamaximumof64ms.NoteTonedetectionandechodisablingareperformedoutsidetheECautomaticallyintheDSPfirmware.Cisc

4、oIOSsoftwaresupportsthefollowingimprovementswiththeextendedEC:•Configurationandreportingofextendedechopathcapacity•Configurationandreportingofworst-caseechoreturnloss(ERL)•Testmodesupportformanuallyfreezing,thawing,andclearingtheECh-register•Reportingofstatisticsfo

5、rlocationofthelargestreflector•ReportingoftheinternalstateoftheECThisfeatureprovidesthefollowingadditionalbenefits:•Nochangestoplatform—ImprovesplatformfunctionalitybyupdatingtheECmodulethroughaDSPWareupgradeandaCiscoIOSsoftwareupgrade•Enablinganddisablingofnonline

6、arprocessor—Enablesanddisablesnonlinearprocessor(NLP)spectrallymatchedcomfortnoise•Echoreturnloss(ERL)configuration—Canbesettothreevalues:0dB,3dB,and6dB•ExpansionofEchoCancellerCapacity—ECcapacityisexpandedto64msTable1containsspecifichigh-complexityandmedium-comple

7、xitysupportlistedbyplatform.Forhardwaresupportdocumentation,refertolinksprovidedinthe“RelatedDocuments”sectiononpage61.CiscoIOSRelease12.2(13)Tand12.2(13)ZH1EnhancedITU-TG.168EchoCancellationFeatureSpecificationsforEnhancedITU-TG.168EchoCancellationFeatureHistoryRe

8、leaseModification12.2(13)TThisfeaturewasintroduced.12.2(13)ZHThisfeaturereplacestheCiscoG.165ECwiththeextendedG.168ECasdefaultontheCisco1700serie