1.CVC kunye nokunciphisa ingxolo ye-DSP:
Xa abathengi bethenga ii-headsets zeBluetooth, baya kuhlala beva i-CVC kunye ne-DSP imisebenzi yokunciphisa ingxolo eyenziwa ngabathengisi ekukhuthazeni ii-headphones. Kungakhathaliseki ukuba bangaphi abasebenzisi abazivileyo iinkcazo, abathengi abaninzi abakawuqondi umahluko phakathi kwezi zimbini. Umahluko, kwingxaki enjalo yobugcisa, siza kwisayensi yezi zimbini phantsi komgaqo wokusebenza kunye nokwahlukana.
I-DSP sisishunqulelo sokwenziwa komqondiso wedijithali. Umgaqo wayo wokusebenza: i-microphone iqokelela ingxolo yokusingqongileyo yangaphandle, kwaye emva koko ngomsebenzi wenkqubo yokunciphisa ingxolo ngaphakathi kwi-earphone, iphinda iphinde ivelise isandi sesandi esijikelezayo esilingana nesandi se-ambient, esicima ingxolo kwaye ngaloo ndlela siphumelele ngakumbi. Isiphumo esihle sokunciphisa ingxolo.
I-CVC imfutshane kwi-Clear Voice Capture. Yiteknoloji yokunciphisa ingxolo yesoftware. Umgaqo kukucinezela iintlobo ezahlukeneyo zengxolo yokubuyisela nge-software eyakhelwe-ngaphakathi yokurhoxisa ingxolo kunye nemakrofoni.
Umahluko ngolu hlobo lulandelayo:
a. kuba into yahlukile, iteknoloji yeCVC ubukhulu becala i-echo eyenziwe ngexesha lokufowuna, i-DSP ikakhulu yengxolo ephezulu nephantsi kwimo yangaphandle.
b. abaxhamli abohlukeneyo, itekhnoloji ye-DSP ikakhulu yenza abasebenzisi be-headset bafumane umvuzo wobuqu, kwaye i-CVC ixhamlisa elinye iqela.
Isishwankathelo, ii-headphones zisebenzisa i-DSP kunye ne-CVC iteknoloji yokunciphisa ingxolo inokunciphisa ngokufanelekileyo ingxolo yendawo yangaphandle yomnxeba, kwaye iphucule kakhulu umgangatho wefowuni kunye nesandi se-headphones.
2.ANC Ukunciphisa ingxolo:
I-ANC ibhekisa kwi-Active Noise Control, enciphisa ingxolo. Umgaqo osisiseko kukuba inkqubo yokunciphisa ingxolo ivelisa amaza omsindo abuyela umva alingana nesandi sangaphandle, ithobisa ingxolo. Umzobo woku-1 yidayagram ecwangcisiweyo ye-feedforward ingxolo esebenzayo yokucima i-earphone. Itshiphu yeANC ifakwe ngaphakathi kwi earphone. Imakrofoni yereferensi (i-microphone yereferensi) iqokelela ingxolo ekwi-earphones. I-Error mic (I-Error Microphone) Iqokelela ingxolo eshiyekileyo emva kokunciphisa ingxolo kwi-earphone. Isithethi sidlala ingxolo yokuchasa emva kokwenziwa kwe-ANC.
Isazobe sesi-2 ngumzobo wenkqubo ye-ANC, enemigangatho emithathu, eyahlulwe ngemigca edayiweyo. Eyona ndlela iphezulu engundoqo lijelo le-acoustic ukusuka kwi-mic ye-ref ukuya kwi-mic yemposiso, umsebenzi wempendulo umelwe yi-P(z)P(z); umaleko ophakathi ngumjelo we-analog, apho umendo wesibini ngumendo osuka kwimveliso yokucoca eguquguqukayo ukuya kwintsalela yokubuyisela. Kubandakanya iDAC, isihluzi sokwakha kwakhona, iamplifier yamandla, ukudlala kwakhona kwesithethi, ukufumana kwakhona, i-pre-amplifier, isihluzo esichasene ne-aliasing, i-ADC; umaleko ongezantsi ngumendo wedijithali, apho isihluzi esiguquguqukayo sihlala silungelelanisa ubunzima be-coefficient yokunciphisa intsalela de ukudibana. Esona sisombululo siqhelekileyo kukuphumeza isihluzo esiguquguqukayo usebenzisa isihluzo se-FIR ngokudibanisa ne-algorithm ye-LMS. Yenza lula umfanekiso wesi-2 kwaye ufumane umfanekiso wesi-3.
Makhe ndithethe ngokufutshane malunga nemigaqo yesihluzo esiguqukayo kunye ne-LMS (Ubuncinci buthetha isikwere) i-algorithm, kwaye emva koko uMfanekiso 3. Njengoko kubonisiwe kuMfanekiso 4, unikwe igalelo xx kunye nemveliso efunwayo dd, isihluzo esiguqukayo sihlaziya i-coefficients lonke uphindo ukuze Umahluko phakathi kwemveliso yy kunye ne-dd iba ncinci kwaye incinci de intsalela isondele ngokwaneleyo ukuya ku-zero kwaye iyadibana. I-LMS luhlaziyo lwealgorithm yezihluzo eziguqukayo. Umsebenzi wenjongo ye-LMS sisikwere semposiso ekhawulezileyo e2(n)=(d(n)−y(n))2e2(n)=(d(n)−y(n))2, ukuze kuncitshiswe umsebenzi wenjongo, Ukusebenzisa ukuhla komgangatho kunika ifomula ehlaziyiweyo yealgorithm. (Ingcamango ye-algorithmic yokusebenzisa ukwehla komgangatho ukunciphisa injongo kunye nokufumana ifomula ehlaziyiweyo yeparamitha ekufuneka ifunwe ixhaphake kakhulu, njengokuhlehla komgca.) Ifomula yohlaziyo ye-algorithm ye-LMS usebenzisa isihluzo se-FIR yile: w(n+1) ) =w(n)+μe(n)x(n)w(n+1)=w(n)+μe(n)x(n), apho uμμ bubungakanani benyathelo. Ukuba ubungakanani be-μμ buhlengahlengiswa ngokuphinda-phinda, linyathelo ngenyathelo le-algorithm ye-LMS.
Masithethe malunga noMfanekiso 3. Apha isihluzo esiguqukayo siphuma emva kwe S(z)S(z) ukuthelekisa nemveliso yomnqweno. I-S(z)S(z) iya kubangela ukungazinzi. Kuncwadi, "uphawu lwempazamo 'alulungelelwanga' ngokuchanekileyo Ekuhambeni kwexesha kunye nomqondiso wesalathiso", ukuhlangana kwe-LMS kwaphukile. (Andikhange ndiyiqonde ukuba ithetha ukuthini T__T) Indlela esebenzayo yi FXLMS (Ihluziwe-X LMS), evumela u-x(n) ukuba abe igalelo kumnqongo weLMS ngokudlula Sˆ(z)S^(z), Sˆ( z S^(z) luqikelelo lwe-S(z)S(z). Injongo yeFXLMS:
E2(n)=(d(n)−s(n)∗[wT(n)x(n)])2,
E2(n)=(d(n)−s(n)∗[wT(n)x(n)])2,
Ngoko ke igradient=−2e(n)s(n)∗x(n)−2e(n)s(n)∗x(n), apho u-s(n)s(n) ingaziwa, ngoqikelelo lwayo, ngoko ke Ifomula yoHlaziyo yeFXLMS yi
w(n+1)=w(n)+μe(n)x'(n),
w(n+1)=w(n)+μe(n)x'(n),
Apho u-x'(n)=sˆ(n)∗x(n)x'(n)=s^(n)∗x(n).
Xa isihluzo esiguqukayo sidibana, E(z)=X(z)P(z)−X(z)W(z)S(z)≈0E(z)=X(z)P(z)−X(z ) W(z)S(z) ≈ 0, ngoko ke W(z) ≈ P(z) / S(z) W(z) ≈ P(z) / S(z). Oko kukuthi, i-coefficient yobunzima bokucoca i-adaptive inqunywe yindlela yokuqala kunye nendlela yesibini yee-headphones. Umendo ophambili kunye nomendo wesibini we-headset uzinzile, ngoko ubunzima be-coefficient ye-adaptive filter izinzile. Ngoko ke, ngenxa yokulula, ubunzima be-coefficients ye-headphones ye-ANC yabavelisi bagqitywa kwifektri. Ewe, amava okumamela ale-earphone ye-ANC ngokucacileyo ayilunganga njengee-earphone ze-ANC ezinentsingiselo yokwenyani eguquguqukayo, kuba kwiimeko zokwenyani, ingxolo yangaphandle enxulumene necala le-earphone, ubushushu obahlukileyo kunye nokunye okunjalo kunokuba nefuthe impendulo yetshaneli ye-earphone.
Ukuqinisekiswa kweMatlab
Bhala ikhowudi yeMatlab, usebenzisa i-adaptive filter of variable size size LMS, iziphumo zokulinganisa ziboniswe kwi-Figure 5. Kuluhlu lwe-0 ukuya kwi-2 kHz, i-ANC ye-feedforward isetyenziselwa ukuphelisa ingxolo emhlophe ye-Gaussian, kunye nokunciphisa ingxolo yi-30 dB + kwi-avareji. I-FXLMS kwithala leencwadi leMatlab linyathelo elimiselweyo, kwaye umphumo umbi.
Q&A
a. Kutheni le nto i-ANC isenzela ingxolo ephantsi engaphantsi kwe-2 kHz?
Ngakolunye uhlangothi, ukufakwa kwesandi somzimba we-headphones (ukunciphisa ingxolo ye-passive) kunokuthintela ngokufanelekileyo ingxolo ephezulu, kwaye akuyimfuneko ukusebenzisa i-ANC ukunciphisa ingxolo ephezulu. Kwelinye icala, ingxolo ye-frequency ephantsi inobude obude kwaye inokumelana nokulibaziseka kwesigaba esithile, ngelixa ingxolo ye-frequency ephezulu inobude obufutshane obunobude obufutshane kwaye inovakalelo lokutenxa kwesigaba, ngoko ke i-ANC iyayiphelisa ingxolo ephezulu.
b. Xa ukulibaziseka kombane kukhulu kunolibaziseko oluphambili, kungacuthwa njani ukusebenza kwe-algorithm?
P(z) ulibaziseko luncinci, S(z) ulibaziseko lukhulu, njenge P(z)=z-1, S(z)=z-2, kuphela xa W(z)=z enokwanelisa iimfuno, non. -isizathu, Ayifikeleleki.
c. Yintoni umahluko phakathi kwe-Feedforward ANC, i-ANC yeqela elimxinwa, kunye ne-ANC ephendulayo?
Ulwakhiwo lweFeedforwad lune-ref mic kunye ne-error mic eqokelela ingxolo yangaphandle kunye neempawu ezishiyekileyo zangaphakathi, ngokulandelelanayo. Ulwakhiwo lwengxelo lunemposiso enye kuphela ye-mic, kwaye isignali yereferensi iveliswa yimposiso ye-mic kunye nemveliso yokucoca eguqukayo.
I-Broad-band feedforward sisakhiwo esichazwe ngasentla. Kwisakhiwo sebhendi emxinwa, umthombo wengxolo uvelisa ijenereyitha yomqondiso wokubangela umqondiso, kwaye ijenereyitha yomqondiso ivelisa umqondiso wesalathiso kwisihluzo esiguqukayo. Isebenza kuphela ekupheliseni ingxolo ngamaxesha athile.
Ingxelo ye-ANC isebenzisa imakrofoni yempazamo ukubuyisela umqondiso oqokelelwe yi-ref mic kulwakhiwo lwe-feedforward kuba inempazamo kuphela. Umendo awanelisi umqobo we-causal, ngoko ke kuphela izahlulo zengxolo eziqikelelwayo, oko kukuthi, ingxolo ye-narrowband periodic, iyapheliswa. Kufuneka kuqatshelwe ukuba ukuba i-feedforward ayiyonelisi isithintelo se-causal, okt ulibaziseko lwe-elektroniki lude kunolibaziseko oluphambili lwe-acoustic channel, lunokuphelisa kuphela ingxolo ye-narrowband periodic.
Kukwakho ne-Hybrid ANC isakhiwo esibandakanya zombini i-feedforward kunye nemibutho yengxelo. Inzuzo ephambili kukuba ungagcina iodolo ye-adaptive filter.
