corrodedadsl宽带

12220WorldTradeDriveSanDiego,California92128TEL:8586748199FAX:8583858003www.
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A(12/09)BackgroundWhileADSLtechnologyprovidesthecapabilitytobringtheInternetintoasubscriber'shomeorofficeoverexistingtelephonewiring,thereisanissuewiththereliabilityofdry(noDCcurrentflow)ADSLandHomePNAconnections.
OxidationCreatesUnreliableDataConnectionsInnormaltelephoneinstallations,anoffhookDCcurrentof20-50mAflowsfromthecentraloffice48Vlinecircuitthroughallofthewiringandjackstothephone(seeFigure1).
Whenthevariousconnectorsandwiringsplicesinthephonecircuitageandcorrode,theycanproduceanopencircuit.
Withnormaltelephoneusage,the48Vfeedvoltagefromthecentralofficeisabletobreakdowntheoxidesandresealtheopenconnections.
Inthisway,thetraditionalphonecircuitcontinuestooperatesatisfactorily.
Unfortunately,theadditionofADSLandHPNconnectionswillnotbeasreliablebecausethereisnoDCloopcurrentflowinginthisportionofthecircuittocleanthejackandplugcontacts.
Inaddition,theexistingwalljacksmayalreadybeagingandcorroded.
ThewipingactionofinstallinganewRJ11cordfortheADSLorHPNconnectioncansometimescleantheoxidefromtheexistingwalljackcontacts,butitmaytakeseveralinsertionstoadequatelycleantheconnectionandtheeffectwillonlybetemporaryatbest.
Thesur-roundingenvironmentswillre-oxidetheconnectionovertime,especiallywhenthejacksarelocatedinhighhumidityareassuchasoutsidewallswithairdraftsand/orgluedpaneling(theoutgassingofconstructionmaterialscanacceleratetheagingprocess).
Astheconnectionscontinuetocorrode,thetransmissionwillbecomenoisyandintermittent,andwilleventuallyfailcompletely.
SolutiontoMaintainingaReliableADSL/HPNConnectionThereisasimplesolutiontothereliabilityproblemthatisneithercostlynordifficult,anditdoesnotrequirenewjackwiring.
Thesolutioncanbeimplementedinoneoftwoways.
.
.
1.
Co-locatetheADSLorHPNmodemconnectionwithatelephonedeviceconnectionsuchasaphone,answeringmachineorfaxmachine.
Themorefrequentlythistelephonedeviceisused,themorereliabletheconnectionwillremain.
a.
Installaduallineadapter(oramicrofilterwithaconvenienceADSL/HPNjack)intotheexistinginsidewalljack(seeFigure1).
Makesuretheduallineadapterorfilterhasatleast50micro-inchesofgoldplatingover100microinchesofnickelinsurelonglife.
Caution:adaptersfromsomedistributorsmayonlyhave5microinchesofgoldflash,whichwillallowearlyfailures.
b.
UsealinecordwithRJ11plugsthathaveaminimum50microinchesofgoldplating.
Thiscordshouldalsobeasinglepairtwisted(notflat)inordertominimizecrosstalkandRFI.
Notethatwhilethetraditional4-conductor,flatcordsmaybesuitableforvoicebandfrequenciesandtelephones,a14-foot4-conductor,flatcordsmaybesuitableforvoicebandfrequenciesandtelephones,a14-foot4-conductorflatcordhasonly3dBofcrosstalklossintheupperHPNbandbetweenLine1andLine2.
c.
ThemanufactureroftheADSLorHPNmodemmustalsoprovidetheminimum50microinchesofgoldplatingontheRJ11jacksintheirmodems.
HPN/ADSLConnectionReliabilityConsiderationsPulseTECHTIP#101www.
pulseeng.
com/excelsus2EX140.
A(12/09)HPN/ADSLConnectionReliabilityConsiderationsPulseTECHTIP#101SolutiontoMaintainingaReliableADSL/HPNConnection(continued)2.
ForADSLorHPNmodemsthathaveapass-throughRJ11telephonejack,connectatelephone,answeringmachine,orfaxmachinetothisjack.
Themorefrequentlythistelephonedeviceisused,themorereliabletheconnectionwillremain.
a.
Installaninlinemicrolterinbetweenthepass-throughjackandthetelephonedevice.
b.
UseasinglepairtwistedlinecordfromthewalljacktothemodeminordertominimizecrosstalkandRFI.
ConclusionTelephone-lineloopcurrentmaintainsareliableconnectiontotelephones,faxmachinesandansweringmachinesthroughtheexistingwalljacks.
Gold-platedcontactsontheco-locateddualjackadapter(orontheconveniencejackofthemicrolter)maintainreliabilityforthedryADSL/HPNmodemportionofthecircuit.
Thecostincreasetospecifyaminimum50microinchesofgoldplatingonallplugsandjacksinthedrycircuitisminimalwhencomparedtotheoverallincreaseinreliability.
AllExcelsusRJ11lters,adaptersandcordshave50microinchesofgoldover100microinchesofnickel.
12220WorldTradeDriveSanDiego,California92128TEL:8586748199FAX:8583858003www.
pulseeng.
com/excelsus3EX140.
A(12/09)HPN/ADSLConnectionReliabilityConsiderationsPulseTECHTIP#101Figure1:ReliabilityConsiderations50MICROINCHGOLDPLATINGONALLDRYWIDEBANDCONNECTIONSPROVIDESTHEMOSTRELIABLEDSLORHPNCONNECTIONSpecificationssubjecttochangewithoutnotice.
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12220WorldTradeDrive,SanDiego,CA92128USADirect:8586748100,Fax:8583858003www.
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