《cisco教材》ppt课件

《cisco教材》ppt课件

ID:40007352

大小:1.92 MB

页数:55页

时间:2019-07-17

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1、CableSolutionsTrainingProgramForUniversalBroadbandRouterandCableModemVisualizingaDOCSISoverHFCNetwork<100ChannelsHeadendCOAXTapDropNodeHubHubNodeNodeCableModemPCNodeNodeNodeNodeNodeHubBroadbandRouteruBR7246TotalNetworkManagementPSTNInternetCNNHBOESPNFNNNodeDOWNSTREAM

2、88-880MHzUPSTREAM5-42MHzAccessinfrastructureServiceProviderCustomerPremisesPOTSISP1ISP2WirelessSONET/ATMBackboneCompACompBISDNServices:InternetAccessOn-lineService TelecommutingCableHead-EndCableHDSLADSLVDSLFanoutShelfNewAccessService5SimpleLabTopologyuBR7223USDSIFRF

3、UpconvertorDiplexFilteruBR904Legend:DownstreamUpstreamBi-directional10BaseTHubDHCP/DNS/TOD/TFTPServerTelnetConnectionConsoleConnectionATTATTHiLoADCBATTATTATTVariableAttenuater303063RepeatforB,C,DtoUSports1,2,3Module2CATVandRFTechnologyOverviewTermsCATV-CommunityAnten

4、naTVNTSC-NationalTelevisionSystemsCommittee:U.S.TVtechnicalstandard,namedaftertheorganizationthatcreateditin1941.Usesa6MHzwidemodulatedsignalPAL-PhaseAlternatingLine.TheTVsystemusedinmostofEuropeandmanyotherplaces,inwhichthecolorcarrierphasedefinitionchangesinalterna

5、tescanlines.Utilizesan8MHzwidemodulatedsignalSECAM-TVsystemusedinFranceandsomeformerSovietbloccountries.Utilizesan8MHzwidemodulatedSignal.SpectrumReuse-CATV’smostfundamentalconceptisspectrumreuse.Historically,theover-the-airspectrumhasbeenassignedtomanyotherpurposes.

6、MuchofitisthereforenotavailableforthecarriageofTV.Theresultisaninadequatesupplyofspectrumtoserveviewersneeds.Cablecanreusespectrumthatissealedinitsaluminumtubes.CoaxialCable-TheprincipalphysicalmediaoverwhichCATVsystemsarebuilt.ThemaindrawbackofCoaxCableisit’srelativ

7、elyhighloss.Coaxsignallossisafunctionofitsdiameter,dielectricconstruction,temperature,andoperatingfrequency(f)TermsCarrier-to-Noise-C/N(alsoCNR):ThedifferenceinamplitudebetweenthedesiredRFcarrierandthenoiseinthatportionofthespectrumSignal-to-Noise-S/N(alsoSNR):Simila

8、rtoC/NbutrelatestoaBaseBandsignalIngressNoise-Over-the-airsignalsthatareinadvertentlycoupledintothenominallyclosedcoaxialcabledistr

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