CombinepowerfeedanddatalinkviacableforremoteperipheralsInmanycommunicationsystems,remotedevicesareconnectedtomainunitsthroughcableassemblies.Thedataandcontrolcommandsareexchangedbetweeneachremotedeviceandthemainunits.Veryoftenthesedevicesareplacedinlocationswithlimitedpoweraccess.Cameramodulesusedinautomotivesafety(backupcameras)andsecuritysurveillanceapplicationsaregoodexamplesofremotedevices.Themostconvenientwaytodeliverpowertothemisthroughthecableassembly.Thisarticleoutlinesthedifferentmethodstosendpowerthroughacableassembly,anddiscussesanimplementationtocombinebothpoweranddataoverasharedtransmissionmedium.PowerfeedwithcopperwiresManytransmissionstandardshaveincorporatedthepowerdistributioncapabilityinthetransmissionmedium.UniversalSerialBus(USB)isanexampleinwhich5VisdistributedthroughapairofcopperwiresintheUSBcableassembly.ItiswidelyusedforprovidingpowertoremoteperipheralsinPCandconsumerapplications.Usingcopperwiresisthemostcost-effectiveandrobustmethodfordeliveringpowertoremotedevices.Thefigurebelowillustratestheuseofadedicatedpairofcopperwirestoprovidepowertoaremotecamera,whilethecapturedimageisserializedbytheDS90UB901QandsentthroughaseparatetwistedpairtotheDS90UB902Qdeserializeratthemainprocessingunit.OnepairofwiresisusedtotransportthevideodataandcontrolinformationthroughtheHYPERLINK"http://en.wikipedia.org/wiki/FPD-Link"\t"_blank"FPD(FlatPanelDisplayLink)-LinkIIIserializeranddeserialzer(SerDes),whiletheotherpairisusedtocarrypower.PowerfeedwithcoaxialcableSharingasingletransmissionmediumbetweensignalandpowereliminatestheneedforasecondpairofwires.Oftenasecondpairmaybedeemedinconvenient,orcannotbeusedforcertainapplications.Theuseofpowerandsignaloverasharedmediumisnotanewconceptandhasbeenwidelyusedintelevisionsignalamplifierslocatedinroof-topantennas(seefigurebelow).PowerisdeliveredbythesamecoaxialcablethatcarriestheantennasignaltotheTVreceiverlocatedinthehouse.Asillustratedinthefigure,DCpowerisinjectedintothecoaxialcablethroughaninductorL1atthesource,