ITU G.165:1993
ITU G.165:1993 Echo Cancellers
Table of Contents
1General2Definitionsrelatingtoechocancellers
2.1Echocanceller
2.2Echoloss(AECHO)
2.3Puredelay(tr)
2.4(Near-end)echopathorenddelay(td)
2.5Cancellation(ACANC)
2.6Residualecholevel(LRES)
2.7Nonlinearprocessor(NLP)
2.8Nonlinearprocessingloss(ANLP)
2.9Returnedecholevel(LRET)
2.10Combinedloss(ACOM)
2.11Convergence
2.12Convergencetime
2.13Leaktime
3Characteristicsofechocancellers
3.1General
3.2Purpose,operationandenvironment
3.3Externalenabling/disabling
3.4Testsandrequirementsforperformancewithinputs
signalsappliedtothesendandreceivepaths
4Characteristicsofanechocancellertonedisabler
4.1General
4.2Disablercharacteristics
4.3Guardbandcharacteristics
4.4Holding-bandcharacteristics
4.5Operatetime
4.6Falseoperationduetospeechcurrents
4.7Falseoperationduetodatasignals
4.8Releasetime
4.9Otherconsiderations
5Nonlinearprocessorsforuseinechocancellers
5.1Scope
5.2Generalprinciplesandguidelines
AnnexAEchocancellerswithoutnonlinearprocessing
AnnexBDescriptionofanechocancellerreferencetone
disabler
B.1General
B.2Disablercharacteristics
B.3Guardbandcharacteristics
B.4Holding-bandcharacteristics
B.5Operatetime
B.6Falseoperationduetospeechcurrents
B.7Falseoperationduetodatasignals
B.8Releasetime
AnnexCDescriptionofareferencenonlinearprocessor
C.1General
C.2Suppressionthreshold(TSUP)
C.3Staticcharacteristicsofactivationcontrol
C.4Dynamiccharacteristicsofactivationcontrol
C.5Frequencylimitsofcontrolpaths
C.6Testing