Recently,alotofdigitalsubscriberloopsystems(DSL)andhighratedigitalsubscriberloopsystems(HDSL)havebeendeployedindigitalsubscriberaccessnetworks.DataechocancellerisextensivelyusedintheDSLandHDSLsystemstorealizefullduplextransmissionontwistedcable.Insuchsystems,2B1Qlinecodeisadopted.Therefore,symbolrateisdecreasedanddigitaltransmissionsystemsgetlongerreach.Inthispaper,aperformanceevaluationmethodoftheechocancellerisproposedbasedonanautocorrelationmatrixof2B1Qlinecode.Usingthismethod,theformulaofratioofdatasignaltoechoresidualsignalisobtained.Accordingtotheformula,theratioofdatasignaltoechonoisedependsonFIRfiltertap,convergencefactor,adaptivealgorithmandthecorrelationmatrixofthelinecode.Computersimulationiscarriedouttoverifytheoreticalanalysis.Thesimulationresultscoincidedwiththetheoreticalformulaintheprocessestimatingtheratioofsignaltonoise.
