a millimeter-wave radar for train application

AMillimeter-waveRadarforTrainApplication-__tRFModuleSliinsakuNoda,KenjiInoiiiata,MasahiroWatanabe,TadamasaFukae,and*MasaniiTobiokac-SSModulator/--cDemodulatorIFPartIndustrialElectronics&SystemsLaboratory,MitsubishiElectricCorp.,AmagasakiCity,Hyogo661-8661,JAPANTransmission&Distribution,TransportationSystemsCenter,MitsubishiElectricCorp.,AmagasakiCity,Hyogo661-8661,JAPANAbsfrucl-Amillimeter-waveradarusingspreadspectrumtechniquefortrainapplicationshasbeendevelopedat60GHzband.Thisradarmeasuresthedistance,velocity,azimuthangle,andthemagnitudeofreceivedsignalofeachtarget.Themethodsfordetectionaredescribedinthispaper.Intheexperiment,theradardetectedthelinearshapeoftrains.part,SSinodulator/demodulator,dataprocessing/beamScancontroller(pc),anddatadisplaypc.Tx/RxandRFmodulearecolllbinedinSamehardware*A.RFModtile(andAntennas)I.INTRODUCTlONTraditionalwaytoleadthetraininthetraindepotdependsoninstructionbytheguidepersonwhoiswatchingobstaclesaroundthetrain.Withasensorwatchingaroundthetrain,anefficientandsafemanagementwillbedone.Inanothersituation,theobstacledetectionsensorsarenwdedforautomatedmovingofthetrain.Moreover,theautomaticcouplingwillbeavailablewithsomesensor.Therefore,Itisveryimportanttodeveloptheobstacledetectionsensorforvarioustrainapplications.Inthispaper,wereportabouta60GHz-bandmillimeter-waveradarusingSpreadSpectrum(SS)technique.Thisradarmeasuresthedistance,velocity,azimuthangle,andmagnitudeofreceivedsignalofeachtarget.Theexperimentalresultattherailroadfieldwillbeshown.11.STRUCTUREOFRADAR€.lockdiagramoftheradarsystemisshowninFig.1.DataDisplayPCDataProcessing/ControllerFig.1.BlockdiagramofradarsystemTheradarsystemconsistsofTdRxantennas,RFmodule(includesmechanicalbeamscanningunit),IF0-7803-5296-3~,9/$10.00BlockdiagraminsidetheRFmoduleisshowninFig.2.AppearanceofRFmoduleisalsoshowninFig.3.Beamscanningmechanismsso5G~24SGHztControlsignalFig.2.BlockdiagramofRFmoduleFig3AppearanceofRFmodule2.45GHzIFsignalfortransmissionisup-convertedto60.5GHzRFsignal,andtransmittedbyTxantenna.Thereceivedsignalisdown-convertedto2.45GHzIFsignalby.RFmodule.TxandRxbeamangleiscontrolledsyncli~onouslybythebeamscanningmechanism.Non-RadiativeDielectric(NRD)waveguideisusedateachRFdevice.HPFafterthetransmittingmixerisinsertedtorejectLOleakagesignalandtheimagesignal(55.6GHz).AnotherHPFbeforereceivingmixerisinsertedtoavoidtransmissionofLOleakagesignalfromreceivingmixerbyJbantenna.ElectricalperformanceofRFmoduleisshowninTableI.Beamscanningmechanismiscontrolledtoanyangleinrtl5bythecontrolsignalfi-omcontrollerPC.Tomeasuretheazimuthangleoftarget,7beamsarelaidoutatevery5in*15.Scanningmechanismscansthese153beams.RFfrequencyBandwidthTransmittedTABLEIELECTRICALPERFORMANCEOFRFMODULEItemIValueICondition60.5GHzIF2.45GHz-1OOMHzPNcliiprate=SOMHz-1OdBniPower1(o.I~w)IAntennagainI30dBiIFrontangleIBeamwidthI5”I-3dBbandwidthJB.IFPar1BlockdiagramofIFpartisshowninFig.4.Xh--------1Fig.4.BlockdiagramofJFpartFunctionofIFpartissimilartoRFmodule.BecauseSSmodulatorordemodulatorprocessesSSsignalofI40MHz(*5OMHz),IFpartup-convertsfroinI40MHzto2.45GHzforthetransmittedsignal,down-convertsfrom2.45GHztoI40MHzforthereceivedsignal.AttenuatorsatLO(2.31GHz)signallineareinsertedbecauseoftworeasons.Oneistoadjustthedrivelevelofmixers.Anotheristoincreasetheisolationbetweentransmittingpartandreceivingpart.C.SSModulalor/Demodulaiol.BlockdiagramofSSmodulator/demodulatorisshowninFig.5.ToIFI40MHrFroniBPSKModuIaIorI40MHri-&--/-~+~beatsignal(Q)iFig.5.BlockdiagramofSSnindulator/demodulator(PNG)generatesPNcodethatisM-sequenceof1023codelength.Sinewaveof140MHzisBinaryPhaseShiftKeying(BPSK)modulatedbyPNcode,andmodulated(spreadinfrequencydomain)signalistransmittedtoIFpart.2)SSDemohilator:Receivedsignalismixedwith“ReferencePNcode”.ThepatternofreferencePNcodeissametotransmittedPNcode,andcontrollerPCcontrolsthephasedifferencebetweentransmittedandreferencePNcodeatevery1/3chip.ThecorrelationofreceivedandreferencePNcodeiscalculatedinthecorrelator,anditsvalueisusedasthesourceofrangingatsignalprocessingPC.Ontheotherhand,thebeatsignalbetweenreceivedandreference(transmitted)frequencyisgeneratedasbothin-phase(1)andquadrature-phase(0).ThesebeatsignalsareusedforthesourceofcalculatingvelocitythatcausestheDopplershiftoffrequency.D.SignalPlacessiiig/Controller(PC)AtthisPC,thedistance,velocity,andazimuthangleofeachtargetarecalculatedfromthecorrelationsignalandI-QbeatsignalsgeneratedatSSdemodulator.Thecalculatingmethodisdescribedlater.Inaddition,thisPCalsocontrolsthebeamscanningnieclianisminRFmodule.Asdescribedlater,azimuthangleiscalculatedbasedonthemagnitudeofreceivedsignalfromthetarget.Therefore,thisPCmustmanagethebeamangle.Calculateddataaresentto“datadisplayPC”throughRS-232Cserialinterface.ThefunctionsdoneinthisPCwillbeeasilyrealizedonthemicroprocessor.E.DataDisplayPCThecalculateddataatsignalprocessingPCaregraphicallydisplayedonthisPC.Itisnowonderthatdisplayingsoftwarecansavedatainrealtime.Atthistime,thisPConlydisplaysdata,althoughitwillbeabletodotargetidentificationsuchastrain,person,orotherobstaclesinthedepot