无线电通信平台的实现算法的外文文献0130101142Word文档格式.docx

无线电通信平台的实现算法的外文文献0130101142Word文档格式.docx

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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