简介:Recently,alotofdigitalsubscriberloopsystems(DSL)andhighratedigitalsubscriberloopsystems(HDSL)havebeendeployedindigitalsubscriberaccessnetworks.DataechocancellerisextensivelyusedintheDSLandHDSLsystemstorealizefullduplextransmissionontwistedcable.Insuchsystems,2B1Qlinecodeisadopted.Therefore,symbolrateisdecreasedanddigitaltransmissionsystemsgetlongerreach.Inthispaper,aperformanceevaluationmethodoftheechocancellerisproposedbasedonanautocorrelationmatrixof2B1Qlinecode.Usingthismethod,theformulaofratioofdatasignaltoechoresidualsignalisobtained.Accordingtotheformula,theratioofdatasignaltoechonoisedependsonFIRfiltertap,convergencefactor,adaptivealgorithmandthecorrelationmatrixofthelinecode.Computersimulationiscarriedouttoverifytheoreticalanalysis.Thesimulationresultscoincidedwiththetheoreticalformulaintheprocessestimatingtheratioofsignaltonoise.
简介:不知不觉中,明基的Joybook已经更新到了第二代。在明基BenQ品牌发布两周年之际,明基推出了全新系列笔记本,除了新型号Joybook6000以外,还有Joybook8000的升级版Joybook8100,Joybook5000系列的升级版Joybook5100。这次我们给大家介绍的就是Joybook5100.Joybook5100在Joybook5000基础上做了不少改进,Joybook5100整体给人感觉没有Joybook5000那么跳,不像Joybook5000那样曲线玲珑,Joybook5100的线条比较平滑,走的是中性化路线,这样更易让大众接受。