无线电通信平台的实现算法的外文文献0130101142.docx
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无线电通信平台的实现算法的外文文献0130101142
AnalysisandImplementationofaNovelSingleChannelDirectionFinding
AlgorithmonaSoftwareDefinedRadioPlatform
JohnJosephKeaveny
Capter1
Aradiodirectionfinding(DF)systemisanantennaarrayandareceiverarrangedinacombinationtodeterminetheazimuthangleofadistantemitter.Basically,allDFsystemsderivetheemitterlocationfromaninitialdeterminationoftheangle-of-arrival(AOA).
Radiodirectionfindingtechniqueshaveclassicallybeenbasedonmultiple-antennasystemsemployingmultiplereceivers.ClassictechniquessuchasMUSIC[1][2]andESPRITusesimultaneousphaseinformationfromeachantennatoestimatetheangle-of-arrivalofthesignalofinterest.Inmanyscenarios(e.g.,hand-heldsystems),however,multiplereceiversareimpractical.Thus,singlechanneltechniquesareofinterest,particularlyinmobilescenarios.AlthoughtheamountofexistingresearchforsinglechannelDFisconsiderablylessthanformulti-channeldirectionfinding,singlechanneldirectionfindingtechniqueshavebeenpreviouslyinvestigated.
Whenconsideringsinglechanneldirectionfindingsystems,wefindthattherearetwodistincttypesofDFsystems.ThefirsttypeofDFsystemistheamplitude-basedDFsystem.Amplitude-basedsystemsdeterminethebearingofthesignal(ortheAOA)byanalyzingtheamplitudesoftheoutputvoltagesfromeachantennaelement.AmplitudeDFsystemsincludetheWatson-WatttechniqueusinganAdcockantennaarray.
ThesecondtypeofDFsystemisthephase-basedDFsystem.Phase-basedsystemsusethreeormoreantennaelementsthatareconfiguredinawaysothattherelativephasesoftheiroutputvoltagesareuniqueforeverywavefrontangle-of-arrival.Phase-basedDFsystemsincludethePseudo-Dopplertechniquewithacommutativeswitchbasedantennaarray.
Sincebothoftheabovetechniquesareprimarilyanalogtechniquesandhavebeenanalyzedinpreviouswork,wewillinvestigateanewsinglechanneldirectionfindingtechniquethattakesspecificadvantageofdigitalcapabilities.Specifically,weproposeaphase-basedmethodthatusesabankofPhase-LockedLoops(PLLs)incombinationwithaneight-elementcirculararray.OurmethodissimilartothePseudo-Dopplermethodinthatitsamplesantennasinacirculararrayusingacommutativeswitch.IntheproposedapproachthesampleddataisfedtoabankofPLLswhichtracksthephaseoneachelement.TheparallelPLLsareimplementedinsoftwareandtheiroutputsarefedtoasignalprocessingblockthatestimatestheAOA.
ThisthesispresentsthedetailsofthenewalgorithmandcomparesitsperformancetoexistingsinglechannelDFtechniquessuchastheWatson-WattandthePseudo-Dopplertechniques.WealsodescribetheimplementationofthealgorithmonaDRSSignalSolutionsIncorporated(DRS-SS),WJ-8629ASoftwareDefinableReceiverwithSunrise.Technologyandpresentmeasuredperformanceresults.Simulationsonasignalwith10dBSNRhaveshownthattheWatson-WattalgorithmandthePseudo-Doppleralgorithmhaveanaccuracythatisworsethantheproposedtechniquebyapproximatelyanorderofmagnitude.
Thealgorithmwasimplementedonasingle-channelDSP-basedsoftwareradiowithahomemadeeight-elementcircularantennaarray.TheWJ-8629AsoftwaredefinedradioreceiverwasprovidedbyDRS-SSinordertoimplementouralgorithm.TheimplementationwastestedusingaCWsignalat~1.57068GHzinalowmultipathlaboratoryenvironmentandoutdoors.TheperformanceoftheprototypeiscomparedtothedataprovidedbythesimulationsinMatlab.
ImplementationresultsfocusonCWmeasurementsinarelativelybenignlaboratoryenvironmentforproof-of-concepttesting.Thisdocumentwillshowthatthebasicversionofthealgorithmcanresultinasignificantcomputationalburden,thusweinvestigatealow-complexityapproachanddemonstrateitsperformance.Itwillbeshownthatasignificantcomputationalreductioncanbeachievedwithminimalperformancepenalty.
1.1SoftwareIntroduction
Duringourresearch,allofthesingle-channeldirectionfindingsimulationswereperformedusingtheMATLAB6.1software.Afterthesimulationswerecompleted,theMATLABcodewasthenportedtohardwareforimplementationusingtheCprogramminglanguage.TheinitialCprogramswerewrittenandtestedtoprovethatthealgorithmscouldbeimplementedontheTIbasedsoftwareradio.AftertheCprogramsweretestedandcomparedtotheirMatlabcounterparts,theywerethenoptimizedfortheTexasInstrumentsTMS320C67xDigitalSignalProcessor.
1.2HardwareIntroduction
1.2.1DRSSignalSolutions,IncorporatedWJ-8629ASoftware
TM
DefinableReceiverwithSunrise.Technology
TheimplementationwasperformedonaTexasInstrumentsDSP-basedWJ-8629AsoftwaredefinedradioprovidedbyDRS-SS.Ithasafrequencyrangefrom20to2700MHzwith10-Hzresolution,receiverfilteringwith22filterslots(200Hzto1.23MHz),and5reservedslotsforuser-downloadablecustomfiltersThemainprocessingunitistheTexasInstrumentsTMS320C6701DSPprocessorwithamaximumcomputationalrateofnearly1GFlops.TheradioallowsonetodevelopalgorithmsforcertainsignalprocessingmodulesintheCprogramminglanguageortheTMS320C67xassemblylanguage.Otherdetailsoftheradioarenotlistedhereduetotheirproprietarynature.Throughoutthisthesiswewillincludeonlythosedetailsnecessaryforproperunderstandingoftheimplementation.
1.2.2MPRGAntennaArray
Theantennabaselineisthegeometriclineofinterconnectionbetweenantennaelements.Antennaapertureisdefinedastheplanesurfaceareaneartheantennathroughwhichmostoftheradiationflows.Thespacingbetweenantennaelementsusuallydeterminestheapertureofanarray,andsinceweareusingcirculararrays,thediameteroftheentirecirculararraydeterminesthearrayaperture.
Inordertomodeltheantennaarray,assumingasingleplanewaveimpingingonthearray,thearraymanifoldvectorforauniformcirculararraycanbewrittenas:
u「e」AR'sinz-1
e」2二R,sin「cos—2
whereRistheradiusofthecircularantennaarray,:
istheelevationangle,0istheangleofarrival(AOA)oftheincomingplanewave,nmistheangleofthemth
antennaelementintheazimuthalplane,andisthewavelengthofthecenterfrequencyofinterest.Forsimplicity,theelevationangleissetto90。
inordertoconsiderazimuthanglesonly.Wedonotconsidertheeffectsofdifferentelevationsinthisstudy.
TheMPRGantennaarrayasseeninFigure1.1isaneight-elementantennaarraywithadiameterof~19.1cm.Wedesiretohaveawaveformthatcompletesonewavelengthoverthediameterofthearraywhichwillbediscussedindetailinlaterchapters.Therefore,thefrequencyoftheCWisdefineda1s=c/入or1.57068GHz.Chapter2
IntroductiontoSingleChannelDirectionFinding
Todate,thetwoprimarymethodsthathavebeenexaminedforsinglechanneldirectionfindingaretheWatson-WattMethodusinganAdcockantennaarray,andthePseudo-DopplerMethodusingacommutativeswitchwithacircularantennaarray.Whilelittleisavailableintheopenliteratureconcerningthesetwotechniques,whatisavailableassumesananalogreceiverandoperatesatrelativelylowfrequencies.Specifically,theAdcock/Watson-Wattalgorithmistypicallyusedforfrequenciesuptoabout1000MHz,whilethePseudo-Doppleralgorithmtypicallyhasanoperationalbandwidthfrom2-2000MHz.Inthischapter,wewilldiscusstheamplitude-basedWatson-Watttechnique,thephase-basedPseudo-Dopplermethod,andanamplitude-basedPseudo-Dopplertechniquedevelopedaspartofthecurrentresearch.Wewilldiscusstheirstrengthsandshort-comingsandmotivatetheinvestigationofnewtechniques.
2•仃heWatson-WattMethod
Watson-WattDFisanamplitude-basedmethodthatusestherelativeamplitudeoftheoutputoftwoantennaarraysarrangedaccordingtotheAdcockdesign.TheAdcockdesignconsistsoffourantennaelementsinaperpendicular,crossed-baseline
configurationasseeninFigure2.1.
Thismethodcanbeusedforfrequenciesuptoabout1000MHz.OneAdcockpaircontainstwoantennaarrays(fourantennaelements)inaperpendicularconfiguration,withelementspacingoflessthanonehalfthewavelengthatthehighestoperatingfrequency.Theazimuthgainpatternfromeachantennaarrayisobtainedbyavectordiffereneeofsignalsfromeachoftwoantennas.
Thesignalsseenonthefourantennasincomplexbasebandnotationare:
wherer(t)isthereceivedsignal,Ristheradiusofthecircularantennaarray,isthewavelengthofthecenterfrequencyofinterest,m(t)isalinearlymodulatedmessagesignaland①istheAOA[6].TheEastantennarepresentsour0oreferenee.
TheNandSantennapaircreatestheY-axisvoltage,whichhasamaximumgainalongtheY-axis.Inotherwordswhen:
」-90°,theeastandwestsignalsareequalandthusx(t)=re(t)-rw(t)=0,whereasy(t)=rn(t)-rs(t)=2m(t).TheEandWantennapaircreatestheX-axisvoltage,whichhasmaximumgainalongtheX-axis.Inotherwordswhen:
:
」=0°,thenorthandsouthsignalsareequalandthus(t)=re(t)-rw(t)=2m(t),whereasy(t)=rn(t)-rs(t)=0.
Target
Q
XT
\OOA
Figure2.1AdcockAntennaArrayusedforWatson-WattAlgorithm
InordertopasstheAOAdatatothesinglereceiver,eachoftheXandYaxisvoltageshavetobecombinedintoacompositesignal.InourexampleinChapter4,
thetwosignalsarelinearlycombinedtoformanAMsignalwithdualtonemodulationinordertopassthedatatothesinglereceiver.
AfterthelinearlycombinedAMsignalreachesthereceiverandAMdemodulationisperformed,theestimatedAOA(*)iscalculate