基于单片机的防盗报警器的设计英文翻译.docx

基于单片机的防盗报警器的设计英文翻译.docx

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基于单片机的防盗报警器的设计英文翻译

本科生毕业设计（翻译）

MultifunctionalIntelligentWirelessAlarmSystem

Abstract:

MakinguseofrichinnerresourceofFPGA（FieldProgrammableGateArrays）,awirelessalarmsendingsystemisdesigned.Itincludesencoder,FSK（FrequencyShiftKeying）modulationandeverychannel’scontrolcircuits,whichcandecreasevolumeandincreasereliabilityofthealarmsystem.ThedemodulationofreceivesystemisrealizedbyanapplicationspecificintegratedcircuitsMC3372.Withthehelpofasingle-chipmicrocomputer89C51,theaddressdecoderisalsodesignedinthereceiver.Addingtootheranti-interference,thealarmingsystemhaseffectivelydecreasedtheerror-alarmrate.

Thesystemcaninstallupto128channelsendingdevices.Itcansendanalarmtothehostwhentherearesomecasesinstand-offareas,andthesystemwilldisplayonrotationmultiplecases’areacodes.Thetransmissiondistanceisgreaterthan4Kminopenzones.Usercaninstallmorethanonetypesensorssimultaneously,forexample,smogsensor,combustiblegassensororburglarsensor.Experimentsshowthatthewirelessalarmsystemhasthestrengthsofhighreliability,highanti-disturbanceabilityandlowerror-alarmrate.Itcanentirelymeettheneedsofalarmfireproofingandguardagainsttheft,etc.

Keywords:

communication;Alarmsystems;FrequencyShiftKeying;Micro-controllers;FieldProgrammableGateArrays

I.INTRODUCTION

Comparedwithawiredalertsystem,awirelessalarmsystemhascharacteristicsofcovertnessandeaseofinstallation.Itisespeciallyeffectivewhentransmittingbetweenlongdistancesinacomplexlandformsituation.MadeupofFPGA（FieldProgrammableGate-Array）,theencodingmoduleinthesendingsystemcreatestheaddresssignal,FSK（frequencyshiftkeying）modulatesthesignalandeachchannel’scontrollersignals.UsingFPGAtoreplaceMSI/SSI（MiddleScaleIntegratedorSmallscaleIntegrated）digitalcircuitdevices,notonlyincreasethereliabilityandtheresistancetointerferenceofthealarmsystem,butitalsodecreasesitsvolumeandmakesthesystemeasiertoinstall.Sinceused7bitsbinarynumbertoexpresstheaddress,upto128channelssendercanbeinstalled.ThedecoderconsistsofASIC（ApplicationSpecificIntegratedCircuit）andSCMinthewirelessalarmreceiversystem,whichcaneffectivelydecreasetheerror-alarmrate.

II.THESENDINGSYSTEMPRINCIPLE

Eachstand-offisequippedwithawirelesssendingsystem,andcorrespondswitha7bitsaddressidentifierinbinary.Onceacaseisdetectedbyasensorinanystand-off,acontrolsignalofthisareaissenttoitsencodingcircuitviainterfacecircuit,whichconvertsthearea’s7bitaddressidentifierintoFSKsignal.ThenFSKsignalistransmittedintoafrequencymodulationcircuitforfrequencymodulating.Afterpoweramplification,thefrequencymodulationelectromagneticwaveisemittedviaantenna.Onecharacteristicofthesendingsystemisdiscontinuoussending.Inotherwords,thesendingsystemdoesnotsendsignalswhenthereisnocase,anddokeepsendingwhenthereisanalarmsituation,soastoprovidechancestosendsignalsforotherstand-offareas.

A.TheEncodingandControllingCircuitConfiguration

ThedigitalcircuitpartoftheencodingcircuitismadebyaFPGAchipwhichincludes8modules.FormedbyDtriggers,module‘dff1’istheinterfacebetweendetectorandencoder.Module‘oscillator’combineswithsomeexternalresistorsandcapacitorstoformacontrollablelowfrequencymultivibrator.Itscontrolsignalistheoutputof‘dff1’---Q1.ItdoesnotvibratewhenQ1isequalto0,andifQ1isequalto1,itvibratestogeneratelowfrequencysquarewaves.Ifsomecasesappearinthearea,theoscillatorcontrolsthemodule‘SENDER’tosendelectromagneticwavediscontinuously.Themodule‘circular_shift_r’isaparallelinputserialoutputcircularshiftregister.ThebitA0～A7aretheparalleladdresscodeinputterminals,whicharejoinedtohighorlowvoltagelevelaccordingtotheencoderrequirement.Q8istheserialoutputterminaloftheaddresscode.Module‘dff2’isacontrolcircuitthatismadeofsomeJKtriggers.ItssetupsignalisQ1,whichalsoactsasatriggersignalafterdelay.Q2actsastheparallel-in-serial-outcontrolterminalofthe‘circular_shift_r’module.WhenQ2isathighvoltagelevel,circular_shift_r’performsparallelinput.WhenQ2isatlowvoltagelevel,‘circular_shift_r’executesserialoutput.Themodule‘delay1’isadelaycircuitcomposedofDtriggers.Themodule‘division’isafrequencydivisionthatcreatesthreedifferentroutesfrequencyoutputsignals,twoofwhichbranchesandactasFSKmodulatingsignals:

f1andf2.Theotherbranchactsasatriggeringpulseformodulesdff1anddelay1,andalsoactsastheclockpulseof‘circular_shift_r’forperformingserial-out.Themodule‘MUX’isa2to1multiplexer.ItscontrolsignalistheoutputQ8of‘circular_shift_r’.WhenQ8＝0,‘MUX’producesthesignalf2,andwhenQ8＝1,itexportsf1.Themodule‘delay2’combineswithsomeexternalresistorsandcapacitorstoformadelaycircuit.Itsfunctionistogiveworkerssometimetoleaveafterinstallingthesystem.Thesendingcircuitdoesnoworkwithinthedelaytime,nomatterwhetherK1（detector）isonoroff.ThisistheexternalconnectiondrawingoftheFPGAchip.

B.TheWorkingPrinciple

Asshownfollowing,theworkingprincipleofthealarmsystemisasfollows:

whenthepowerofthesendingsystemturnson,theinputofthe‘dff1’isatlowlevel.ThenitsoutputterminalQ1isatlogicvalue‘0’,NQ1isatlogic‘1’,andaexternallight-emittingdiode（LED）islittoindicatethepowerison.ThesignalQ1issenttothesettingterminalof‘dff2’tosetterminalQ2athighlevel.ThehighlevelQ2willset‘circular_shift_r’intotheparallelinputaddresscodemode.Atthistime,theoutertransistorN2isatsaturationstateandN3atcut-offstate.Thismakesthesendingcircuitatapassivestate,therefore,thecircuitwillnotwork.Hence,thecircuitdoesnotemitcarrierwaveifthereisnocase,anditisatlowconsumablepowerstate.Oncesomecasesappear,theswitchK1ison.TheterminalDofthe‘dff1’turnstohighlevelimmediately,andtheoutputQ1of‘dff1’issettohighlevelattherisingedgeoftheclockpulse.Itmakesthesettingterminalsof‘dff2’athighleveltoo.The‘dff2’nowisatnormalworkingstate.Afterdelayingbymodule‘delay1’,theformeredgeoftheQ1pulsewilltrigger‘dff2’tooutputlowvoltage,whichwillmakethetransistorN2off,N3on,andthedelay’snormallyopencontactwillbeclosed.Theelectricpowersupplytothesendingcircuitison,andthecircuitbeginstoworknormally.Simultaneously,ifQ2isatlogic0,‘circular_shift_r’willbechangetoserialshiftstateandexportaddresssignals.Whentheaddresscodeis0,theoutputof‘MUX’willbef2.Andwhentheaddresscodeis1,theoutputwillbef1.Terminalsf2andf1actasthemodulationsignalformodulatingthecarrierwave.Inthisway,theaddresscodeissentoutatthefirstcycleofthelowfrequencyoscillator.Atthesecondcycleitstopssendinginordertogiveotherstand-offaperiodoftimetosend.Afterthethirdcycle,repeattheprocedureabove.

Fromthediscussionabove,wehavetheconclusionthattheencodingandcontrolcircuithavethefunctiontodisplaywhenthepowerison,timedelayforhumantoleavethespot,lowpowercostmodeforwaitingcase,discontinuitysendingandFSKmodulatingetc.ItismoreflexibleandhasmorefunctionsthanmanyencoderASIC.

III.THECONFIGURATIONANDPRINCIPLEOFTHERECEIVINGSYSTEM

Setinguardhouse,asetofwirelessreceivertakeschargeofmonitoringallstand-offareas.Theprincipleofthewirelessreceiverisshowfollowing.Passingbythelowpassfilter,thereceivedmodulationsignalissentintothehighfrequencycommon-emitterandcommon-baseconfigurationcascadeamplifierforamplifying.Thenthesignalissenttotheintermediatefrequencymodulationamplifierviathedualtuningcircuit,i.e.sentintotheinputterminal（16thpin）ofanASICchip（MC3372）todomixing.Theoscillatefrequencyofthelocaloscillatorcircuitis455KHzhigherthanthereceivedsignal.DeliveringtothefirstpinofthechipMC3372,thesignalwillmixwiththeexternalsignaltoget455KHzintermediatefrequencysignal.Afterfiltering,theintermediatefrequencysignalisfirstdeliveredtothe8thMC3372pintodofrequencydetection,andsecondamplifiedbyaninnerlowfrequencyamplifierofthechipMC3372,thenthe9thpinexportsthebasebandsignal.Amplifiedbyalowfrequencysingletransistor,thebasebandsignalisrectifiedbytwostepsSchmittgates（CD4584）toturnintoaFSKsignal,whichwillbesentintopin3.0ofMCStobedecoded.

MCSinthissystemischip89C51,whichjoinsanouter12MHZcrystaloscillator.ItstimerT1actasabaudrategeneratorinmode2,andSMOD=1,300baud/sec.serialportisselectedinmode1,whichmeansanasynchronouscommunicationmode,10bitperframeinwhichthelower7bitsofthe8databitistheaddresscode,andthe8thactsastheparitycheckbit.Thesystemusesevencheck.

Whenreceivinganaddresscode,theMCSfirstlyperformsparitycheck.Ifitiscorrect,then,theMCScomparetheirvalueandtakesout7bitsaddresscodeandstoresitintodatabufferinmemory.Theseproceduresrepeat3timesinordertoidentifythe3addresscodes.Ifthe3addresscodesarethesame,theMCSwillconfirmthatthereceivingaddresssignalisaneffectivealarmsignal,thatistosay,theaddresscodeisnotanoisesignal.Itthentriggersthealarmcircuittosendthealarmsound.Atthesametime,thecodenumberwilldisplayonthe