PABX

PABXPrivateAutomaticBranchExchange电话通信系统基本构成:1.终端设备2.传输中继3.路由（交换设备）电话通信的基本原理:发送端将声音转变为电信号,并通过传输线送到接收端,接收端将电信号复原为声音电话机通话电路原理听话电路原理送话放大器由交换机的恒流源直接供电，在恒流原供电方式下，三极管的输出特性曲线将变的非常密集，这时MIC若有话音输入，则将引起极射电压(Vce)的显著变化，这个变化的电压在恒流原端被取出并传输到接听的对方。送话电路原理WhytelephonyneedPABX?IftherewasnoPABX,theconnectionbetweenfourtelephonyisasbelow:Whatif100telephony?Itneeds4950交换原理：TDM时分复用技术电话接续基本流程交换机A中继线交换机B用户线用户线入中继出中继交换机：实现任意两个用户之间通话中继：延伸任意两个通话用户之间的距离信令：对用户通话过程进行控制回铃音信令用户线信令始呼（摘机）拨号音拨号信令复原（挂机）选择信令（路由信令）占用信令应答信令通话后向拆线信令前向拆线信令拆线证实信令局间信令振铃信令应答（摘机）复原（挂机）用户线信令TLU76:TrunkLineUnit.•WHP-EPABXinterfaceswithWHP-BPABXsystemviaaredundantE1link.•PrimaryE1trunklinkisviasub-sefiberopticalcable.•IncaseofFiberopticaltransmissionfailure,PABXsystemwillautomaticallyswitchovertomicrowavebackupE1trunklink.TMU/12:TimingandMultipartyUnitTMUisusedfordigitalgenerationandreceptionoftonesaswellasprovidingconferencefunctionality.ELU33:ExtensionLineUnit,Digital.Itprovides32digitaltelephoneextensions.LPU5:LIMProcessorUnit.•EachLPUcontainsaprocessorsystembuiltaroundtwocommercialmicroprocessor.•A32bitprocessorusedastheLIM’smainprocessorwhilea16bitprocessorisusedasthecommunicationprocessorwhosetaskistoadministerthedirectcommunicationswiththecontrolcircuitsoftheswitchwiththetelephonydevices.DSU:DistributedSwitchUnit.EachoftheDistributionswitchunitsperformserial/parallelconversionofPCMsignalstoandfromthedeviceboards.LSU:LIMSwitchUnit.Itcontainsspeechandcontrolmemoriesfromtimeswitch,andamicroprocessorthatcontrolsinternalfunctionsoftheswitch.Itmaintainscontactwiththecommunicationprocessor.NIU:NetworkInterface.IPLU:IPtelephonyboard.TheswitchportsIPLUwillconnecttowouldbethe9thportoffirstswitchoneachplatform.ALU2:AlarmBoardTLU75:TrunkLineunit,analogue.ThiscardisprovidedforthepurposeofinterfacingtoINMARSATFleet77system.PABXinterfaceswithPAAsystemvia2-wire.Bydialingtheaccesscodeofthischannel,theextensioncanaccesstoPAAsystem.PABXinterfaceunitinsidePAArackstoresthevoicemessagefromPABXextensionandreplaysitafterapredefineddelaytobothAandBsubsystemsofPAAsimultaneously.TLU80:TrunkLineunit,E&M.AvayaEricssonMAX-OneEricssonMAX-OneEricssonMAX-OneEricssonMAX-OneEricssonMAX-OneEricssonMAX-OneIPLUCOPPSTNWHPAWHPBWHPCWHPDWHPEWHPFFPSOE1E1E16xE1E1E1E1E1E1Point-to-PointRadioLinktoWHP-BPoint-to-PointRadioLinktoWHP-BPoint-to-PointRadioLinktoWHP-BPoint-to-PointRadioLinktoWHP-BPoint-to-PointRadioLinktoWHP-BPoint-to-PointRadioLinktoWHP-B6xPoint-to-PointRadioLinkstoallotherfacilitiesBohaiPhaseIIPABXNetworkAvayaE1MingzhuFPSOWillbemovedat2009RouterPlanAllcallsbetweenfacilitiesexceptWHPAshouldberoutedtodestinationdirectlybyIPLU,don’tneedtogothroughWHPB’sPABX.CallbetweenfacilitiesCallonshore,PlatformAandM1.FirstroutingpathAllonshorecallofeachfacilityincludecallingtoWHPAandMshouldberoutedtoWHPB’sPABXbyIPLU,thengooutsidebyE1trunktoCiscorouter.WHP-B’sPABXhasmicrowavelinktoWHPA’sPABX(Avaya).OncetheE1trunktoCiscorouterofWHPBisfailure,allonshorecallwillgotoWHPA’sPABXbymicrowave.2.SecondroutingpathOnceWHPB’sPABXisfailure,allonshorecallofeachfacilityincludecallingtoWHPAandMingzhuFPSOshouldberoutedtoWHPC’sPABXbyIPLU,thengooutsidebyE1trunktoCiscorouter.