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1英文原文：AutomaticmeterreadingsystemThepresentinventionrelatestoautomaticmeterreading.Moreparticularly,thepresentinventionrelatestoanautomatedsystemforremotelymonitoringapluralityofutilitymetersoncommandfromahostserverviaanRFoutboundbroadcast.BACKGROUNDOFTHEINVENTIONHistorically,metersmeasuringelectricalenergy,waterflow,gasusage,andthelikehaveusedmeasurementdevices,whichmechanicallymonitorthesubscriber'susageanddisplayareadingoftheusageatthemeteritself.Consequently,thereadingofthesemetershasrequiredthathumanmeterreadersphysicallygotothesiteofthemeterandmanuallydocumentthereadings.Clearly,thisapproachreliesveryheavilyonhumaninterventionand,thus,isverycostly,time-consuming,andpronetohumanerror.Asthenumberofmetersinatypicalutility'sserviceregionhasincreased,insomecasesintothemillions,humanmeterreadinghasbecomeprohibitiveintermsoftimeandmoney.Inresponse,varioussensingdeviceshavebeendevelopedtoautomaticallyreadutilitymetersandstorethemeterdataelectronically.Thesesensingdevices,usuallyoptical,magnetic,orphotoelectricinnature,arecoupledtothemetertorecordthemeterdata.Additionally,themetershavebeenequippedwithradiofrequency(RF)transceiversandcontroldeviceswhichenablethemeterstotransmitmeterdataoveranRFlinkwhenrequestedtodoso.Hand-helddeviceshavebeendevelopedwhichincludeRFtransceiversdesignedtointerfacewiththemeters'RFtransceivers.Thesehand-helddevicesenablethehumanmeterreadertosimplywalkbythemeter'slocation,transmitareadingrequestoveranRFlinkfromthehand-helddevicetothemeter'sreceivingdevice,waitforaresponsefromthemeter'ssensingandtransmittingdevice,andthenrecord,manuallyorelectronically,themeterdata.Similarly,meterreadingdeviceshavebeendevelopedfordrive-byreadingsystems.UtilityvansareequippedwithRFtransceiverssimilartothosedescribedinthehand-heldexampleabove.Thehumanmeterreaderdrivesbythesubscriber'slocation,withanautomatedreadingsystemintheutilityvan.Again,themetersarecommandedtoreportthemeterdata,whichisreceivedinthevanviaanRFlink,wherethedataisrecordedelectronically.Whilethismethodologyimprovesuponthepreviousapproaches,itstillrequiresasignificantamountofhumaninterventionandtime.Recently,therehasbeenaconcertedefforttoaccomplishmeterreadingbyinstalling2fixedcommunicationnetworksthatwouldallowdatatoflowfromthemeterallthewaytothehostsystemwithouthumanintervention.Thesefixedcommunicationsnetworkscanoperateusingwirelineorradiotechnology.FIG.1showsaconventionalfixedcommunicationnetworkforautomatedmeterreading(AMR)technology.AsshowninFIG.1,afixedcommunicationnetworkhavingwirelinetechnologyinwhichutilitymeters10areconnectedtoawideareanetwork(WAN)consistingofasuitablecommunicationsmedium,includingordinarytelephonelines,orthepowerlinesthatfeedthemetersthemselves.Onedisadvantageofthisapproachhasbeenthatwhenanumberofmeterstransmitmeterdatanearlysimultaneously,theinherentlatencyonthewideareanetworkresultsinpacketcollisions,lostdata,garbleddata,andgeneraldegradationofintegrityacrossthesystem.Tocompensateforthecollisionsandinterferencebetweendatapackagesdestinedforthecentralcomputer,duetothelatencyinherentintheWAN,variousmanagementschemeshavebeenemployedtoensurereliabledeliveryofthemeterdata.However,whilethisapproachmaybesuitableforsmallsystems,itdoesnotservetheneedsofautilitywhichmonitorsthousandsorevenmillionsofmeters.InanattempttobettermanagethetrafficintheWAN,approacheshavebeendevelopedwhereinmetercontroldevicessimilartothosedescribedabovehavebeenprogrammedtotransmitmeterdatainresponsetocommandsreceivedfromthecentralcomputerviatheWAN.Bylimitingthenumberofmeterreadingcommandstransmittedatagiventime,thecentralcomputercontrolsthevolumeofdatatransmittedsimultaneously.However,theadditionalWANtrafficfurtheraggravatedthedegradationofdataintegrityduetovariousWANlatencyeffects.Thus,whiletheseapproachesmayservetoeliminatetheneedforhumanmeterreaders,relianceontheWANhasproventheseapproachestobeunsatisfactoryforservicingthenumberofmetersinthetypicalserviceregion.Consequently,radiotechnologyhastendedtobethemediumofchoiceduetoitshigherdataratesandindependenceofthedistributionnetwork.ThelatestevolutionofautomatedmeterreadingsystemshavemadeuseofoutboundRFcommunicationsfromafixedsource(usuallytheutility'scentralstation),directlytoRFreceiversmountedonthemeters.Themetersarealsoequippedwithcontroldeviceswhichinitiatethetransferofmeterdatawhencommandedtodosobythefixedsource.ThemetersrespondviaaWANasinthepreviouswire-basedexample.OnedisadvantageoftheseapproachesisthatthereisstillfartoomuchinterferenceontheWANwhenallofthemetersrespondataboutthesametime.Thus,whiletheseapproachesreducesomeoftheWANtraffic(byeliminatingoutboundcommandsovertheWAN),theyarestillunabletoaccommodatethelargenumberofmetersbeingpolled.3Itisworthyofnotethatthewire-basedsystemstypicallyuseasinglefrequencychannelandallowtheimpedanceandtransfercharacteristicsofthetransformersinthesubstationtopreventinjectionequipmentinonestationfrominterferingwithreceiversinanotherstation.Thisbuilt-inisolationinthenetworkmakestimedivisionmultiplexinglesscriticalthanforradiobasedmeteringsystems.Typica