FPGA-Speech-Recognition开源项目

FPGASpeechRecogitio

SimpleSpeechRecogitioSystemusigMATLABadVHDLoAlteraDE0.DemoVideohere

Thisprojectisatrialtodevelopasimplespeechrecogitioegieolow-edadeducatioalFPGAslikeAlteraDE0.Alsoasimplechallegetoexhaustthelimitsoflow-edFPGAsadtammigthemtodoadvacedstuff.Thesystemwasdesigedsoastorecogizethedigit(1or0)beigspokeitothemicrophoeoflaptopthetrasferreditoFPGAoverUART.Bothidustryadacademiahavespetacosiderableeffortithisfieldfordevelopigsoftwareadhardwaretocomeupwitharobustsolutio.However,itisbecauseoflargeumberofaccetsspokearoudtheworldthatthiscoudrumstillremaisaactiveareaofresearch.

SpeechRecogitiofidsumerousapplicatiosicludighealthcare,artificialitelligece,humacomputeriteractio,IteractiveVoiceResposeSystems,military,avioicsetc.Aothermostimportatapplicatioresidesihelpigthephysicallychallegedpeopletoiteractwiththeworldiabetterway.

Speechrecogitiosystemscabeclassifieditoseveralmodelsbydescribigthetypesofutteracestoberecogized.Theseclassesshalltakeitocosideratiotheabilitytodetermietheistacewhethespeakerstartsadfiishestheutterace.IthisprojectIaimedtoimplemetIsolatedWordRecogitioSystemwhichusuallyusedahammigwidowoverthewordbeigspoke.

TheSpeechRecogitioEgiesarebroadlyclassifiedito2types,amelyPatterRecogitioadAcousticPhoeticsystems.Whiletheformerusethekow/traiedpatterstodetermieamatch,thelatterusesattributesofthehumabodytocomparespeechfeatures(phoeticssuchasvowelsouds).Thepatterrecogitiosystemscombiewithcurretcomputigtechiquesadtedtohavehigheraccuracy.

Herecomestheroleofspectralaalysis,bydoigasetoftrasformatiosadprocessigalgorithmsotheicomigsigal,itiscoverteditoausableformthatfurtheraalysiscabedoeoit.

DFT:ThediscreteFouriertrasform(DFT)covertsafiitesequeceofequally-spacedsamplesofafuctioitoaequivalet-legthsequeceofequally-spacedsamplesofthediscrete-timeFouriertrasform(DTFT),whichisacomplex-valuedfuctiooffrequecy.

HammigWidow:WheeveryoudoafiiteFouriertrasform,youareimplicitlyapplyigittoaifiitelyrepeatigsigal.So,ifthestartadedofthefiitesampledo'tmatchthethatwilllookjustlikeadiscotiuityithesigal,adshowupaslotsofhigh-frequecyoseseitheFouriertrasform,whichyoudo'twat.

Adifthesamplehappestobeabeautifulsiusoidbutaitegerumberofperiodsdo'thappetofitexactlyitothefiitesample,yourFTwillshowappreciableeergyiallsortsofplacesowhereeartherealfrequecy.

Widowigthedatamakessurethattheedsmatchupwhilekeepigeverythigreasoablysmooth;thisgreatlyreducesthesortof"spectralleakage".

EuclideaDistace:TheEuclideadistaceorEuclideametricisthe"ordiary"straight-liedistacebetweetwopoitsiEuclideaspace.Withthisdistace,Euclideaspacebecomesametricspace.TheassociatedormiscalledtheEuclideaorm.OlderliteraturereferstothemetricasPythagoreametric.

HammigDistace:Iiformatiotheory,theHammigdistacebetweetwostrigsofequallegthistheumberofpositiosatwhichthecorrespodigsymbolsaredifferet.Iotherwords,itmeasuresthemiimumumberofsubstitutiosrequiredtochageoestrigitotheother,orthemiimumumberoferrorsthatcouldhavetrasformedoestrigitotheother.Iamoregeeralcotext,theHammigdistaceisoeofseveralstrigmetricsformeasurigtheeditdistacebetweetwosequeces.

FFT:TheFFTisafast,O[Nlog(⁡N)]algorithmtocomputetheDiscreteFourierTrasform(DFT),whichaivelyisaO[N^2]computatio.TheFFToperatesbydecomposigaNpoittimedomaisigalitoNtimedomaisigalseachcomposedofasiglepoit.ThesecodstepistocalculatetheNfrequecyspectracorrespodigtotheseNtimedomaisigals.Lastly,theNspectraaresythesizeditoasiglefrequecyspectrum.

ThesystemwasfirstitededtobedevelopeditheFPGAolywithoutexteralequipmetsbutitwasimpossibletodosoduetothelimitedcapabilitiesoftheboardIhave,soIdividedtheprojectito2stages,thefrot-ed(sigalacquisitioadaalysis)adtheback-ed(pattermatchigadestimatio,decisiomakigadUI).

Froted(MATLAB):ThefrotedisbuiltitomatlabduetotheeaseofdoigDSPoitusigbuiltifuctios,wehave2programs,oefortraiigadobtaiigameasigaladtheotherforrealtimeoperatio.stepsdoeimatlabare:

FilesitheFroted:[trai.m,recorder.m]

Backed(AlteraDE0):DuetothelackofADCiAlteraDE0I'mtrasmittigthedatafromthecomputer’smicrophoeusigUSBtoTTLmoduleovertheuartprotocol,thereceiveddataoflegth(1000)samplesarecomparedthewiththesavedvectorsfromthetraiigwithmatlab,theeuclideadistacesarecalculatedadthevectorwithmoreprobabilitytobetherightoeisgiveabiggerweight,weightsarethecomparedthedisplayigthefialresultso7-SegmetsadLEDs.

ThebackedwasmodelledasaMooreFiiteStateMachiewith4states:(Receivig,CalculatigDistace,DecisioMakig,DisplayigResults).FilesitheBacked:[Voice_Recogitio.vhd,uart_tx.vhd,uart_rx.vhd,uart_parity.vhd,uart.vhd]

EuclideaDistaceCalculatio:Calculatiooftheeuclideadistacefor1000poitlegthvectorisveryexpesivetodoiFPGAdirectlyusigforloops,soIdidalittletrickadcalculatedtheweightsofvectorsidirectly,byolycoutigthestateswherethedistaceequalszero,thisapproachissimilartousigK-earesteighbourimachielearig.Iotherwordswearereallycalculatighammigdistaceiversely.

FFTPoitsDiscardig:DuetotheirrelevaceofallthefrequeciesIolytook1000poitsaddiscardedthewholesigal,alsowhiletakigtheFFTIdiscardedhalfthesigalsduetosymmetryoftheoutput.

MooreFSM:Thedesigwasmadeimooremachieforautomaticrecogitioadtodecreasetheuseriteractiowiththesystem,alsoforcomplexityreductio.

UARTModule:UARTwasusedithemodulefortrasmittigdataduetothelimitatiosoftheFPGABoard,adduetothesimplicityofimplemetatioadavailablitiyofcoversiomodulesithemarket.

ItwasshowherethatitispossibletoimplemetabasicspeechrecogitiosystemoAlteraDE0adit’spossibletoovercomethelimitedcapabilitiesofthehardwarebymaysoftwareworkarouds.

Thesystemisabletosuccessfullyrecogizetwodigits(1ad0)toagreataccuracyforthesamespeaker.Thesystemspeakerdepedettoagreatextetduetothelowumberoftestigsamples,thiscabeimprovedbymakigabiggerdatasetfromvariousspeakers,alsobycalculatigadcomparigtheMFCCswithFFTtheapplicatiowillbemoreeffectiveadwithaveryhighaccuracy.

Theavailabilityofmorepowerfulhardware,willallowmetoeasilyimplemetmorerobustalgorithmslikeHiddeMarkovModelsadusemorepowerfulADCChipstorecordsoudmorepurelyresultigimoreaccurateresults.