1.CVC kanye nokunciphisa umsindo kwe-DSP:
Lapho abathengi bethenga amahedisethi e-Bluetooth, bazohlala bezwa imisebenzi yokunciphisa umsindo ye-CVC neye-DSP abathengisi abanayo ekuphromotheni ama-headphone. Akunandaba ukuthi bangaki abasebenzisi abazwile izincazelo, abathengi abaningi abakawuqondi umehluko phakathi kwakho kokubili. Umehluko, ngenkinga enjalo yobuchwepheshe, sifika kwisayensi yalokhu okubili ngaphansi kwesimiso sokusebenza kanye nomehluko.
I-DSP iyisifinyezo sokucubungula isignali yedijithali. Umgomo wayo wokusebenza: imakrofoni iqoqa umsindo wangaphandle kwezemvelo, bese kuthi ngohlelo lokusebenza lokunciphisa umsindo ngaphakathi kwe-earphone, iphindaphinde ukuze ikhiqize igagasi lomsindo elibuyela emuva elilingana nomsindo we-ambient, okhansela umsindo futhi ngaleyo ndlela uzuze okwengeziwe. Umphumela omuhle wokunciphisa umsindo.
I-CVC imfushane yokuthi Ukuthwebula Ngezwi Okucacile. Kuwubuchwepheshe besoftware bokunciphisa umsindo. Umgomo uwukucindezela izinhlobo ezahlukene zomsindo ophindayo ngokusebenzisa isofthiwe eyakhelwe ngaphakathi yokukhansela umsindo nemakrofoni.
Umehluko kanje:
a. ngoba into ihlukile, ubuchwepheshe be-CVC ikakhulukazi i-echo ekhiqizwa ngesikhathi socingo, i-DSP ngokuyinhloko inomsindo wefrikhwensi ephezulu nephansi endaweni yangaphandle.
b. abahlomuli abahlukene, ubuchwepheshe be-DSP ikakhulukazi benza abasebenzisi bama-earphone bathole imali yomuntu siqu, futhi i-CVC izuzisa kakhulu elinye iqembu.
Kafushane, ama-headphone asebenzisa ubuchwepheshe bokunciphisa umsindo we-DSP ne-CVC anganciphisa ngempumelelo umsindo wendawo yangaphandle yocingo, futhi athuthukise kakhulu ikhwalithi yocingo nomsindo wama-headphone.
2.Ukunciphisa umsindo we-ANC:
I-ANC ibhekise kwi-Active Noise Control, ewunciphisa ngenkuthalo umsindo. Isimiso esiyisisekelo siwukuthi uhlelo lokunciphisa umsindo lukhiqiza amaza omsindo ahlehlayo alingana nomsindo wangaphandle, enze umsindo ube lula. Umfanekiso 1 uwumdwebo wohlelo lwe-feedforward esebenzayo ekhanselwayo yomsindo wasezindlebeni. I-chip ye-ANC ifakwe phakathi kwama-earphone. Imakrofoni yereferensi (i-microphone eyireferensi) iqoqa umsindo we-ambient kuma-earphone. Imakrofoni yephutha (Imakrofoni yephutha) Iqoqa umsindo osalayo ngemva kokunciphisa umsindo kuma-earphone. USomlomo udlala ngokungahambisani nomsindo ngemuva kokucutshungulwa kwe-ANC.
Umfanekiso wesi-2 uwumdwebo wohlelo lwe-ANC, onezingqimba ezintathu, ezihlukaniswa ngemigqa edayishiwe. Indlela eyinhloko ephezulu iwumzila we-acoustic osuka ku-ref mic ukuya kumakrofoni wephutha, umsebenzi wokuphendula umelwe ngu-P(z)P(z); ungqimba oluphakathi yisiteshi se-analog, lapho indlela yesibili iyindlela esuka ekukhiqizweni kwesihlungi esiguquguqukayo kuya kwensalela yokubuyisela. Kubandakanya i-DAC, isihlungi sokwakha kabusha, isikhulisi samandla, ukudlalwa kwesipikha, ukutholwa kabusha, i-pre-amplifier, isihlungi esiphikisana ne-aliasing, i-ADC; isendlalelo esingezansi siyindlela yedijithali, lapho isihlungi esiguquguqukayo sihlala silungisa i-coefficient yesisindo sokuhlunga ukuze kuncishiswe insalela kuze kuhlangane. Isixazululo esivame kakhulu ukusebenzisa isihlungi esiguquguqukayo usebenzisa isihlungi se-FIR sihlanganiswe ne-algorithm ye-LMS. Yenza Umdwebo 2 ube lula futhi uthole Umfanekiso 3.
Ake ngikhulume kafushane ngezimiso zesihlungi esiguquguqukayo kanye ne-algorithm ye-LMS (Isikwele esingasho lutho), bese kuba uMfanekiso 3. Njengoba kuboniswe kuMfanekiso 4, uma kubhekwa okokufaka kwe-xx kanye nokuphumayo okufunayo okungu-dd, isihlungi esiguquguqukayo sibuyekeza ama-coefficients njalo ukuphindaphinda ukuze umehluko phakathi kokuphumayo yy kanye no-dd uba mncane futhi ube mncane kuze kube yilapho insalela isondele ngokwanele kuqanda futhi iyahlangana. I-LMS iyi-algorithm yokuvuselela yezihlungi eziguquguqukayo. Umsebenzi wenhloso ye-LMS uyisikwele sephutha elisheshayo e2(n)=(d(n)−y(n))2e2(n)=(d(n)−y(n))2, ukuze kuncishiswe umsebenzi wenhloso, Ukusebenzisa ukwehla kwegradient kunikeza ifomula ebuyekeziwe ye-algorithm. (Umqondo we-algorithmic wokusebenzisa ukwehla kwe-gradient ukuze unciphise umgomo futhi uthole ifomula ebuyekeziwe yepharamitha okufanele ifunwe uvame kakhulu, njengokuhlehla komugqa.) Ifomula yokubuyekeza ye-algorithm ye-LMS kusetshenziswa isihlungi se-FIR ithi: w(n+1) ) =w(n)+μe(n)x(n)w(n+1)=w(n)+μe(n)x(n), lapho u-μμ engusayizi wesinyathelo. Uma usayizi we-μμ ulungiswa ngokuphindaphinda, i-algorithm ye-LMS yesinyathelo nesinyathelo.
Ake sikhulume ngoMfanekiso 3. Lapha isihlungi esiguquguqukayo siphuma ngemva kuka-S(z)S(z) ukuze siqhathanise nokuphuma kwesifiso. I-S(z)S(z) izodala ukungazinzi. Ezincwadini, "isignali yephutha 'ayiqondiswe kahle' Ngokuhamba kwesikhathi nesignali yereferensi", ukuhlangana kwe-LMS kuphukile. (Angikaqondi ukuthi kusho ukuthini T__T) Indlela ephumelelayo yi-FXLMS (Ihlungiwe-X LMS), evumela u-x(n) ukuthi afakwe kumojula ye-LMS esebenzisa Sˆ(z)S^(z), Sˆ( z S^(z) isilinganiso se-S(z)S(z). Inhloso ye-FXLMS:
E2(n)=(d(n)−s(n)∗[wT(n)x(n)])2,
E2(n)=(d(n)−s(n)∗[wT(n)x(n)])2,
Ngakho-ke i-gradient=−2e(n)s(n)∗x(n)−2e(n)s(n)∗x(n), lapho u-s(n)s(n) ingaziwa, nesilinganiso sayo, Ifomula yokuvuselela ye-FXLMS ithi
w(n+1)=w(n)+μe(n)x'(n),
w(n+1)=w(n)+μe(n)x'(n),
Lapho u-x'(n)=sˆ(n)∗x(n)x'(n)=s^(n)∗x(n).
Lapho isihlungi esiguquguqukayo sihlangana, 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, ngakho-ke W(z) ≈ P(z) / S(z) W(z) ≈ P(z) / S(z). Okusho ukuthi, i-coefficient yesisindo sesihlungi esiguquguqukayo sinqunywa indlela eyinhloko kanye nendlela yesibili yamahedfoni. Umzila oyinhloko kanye nendlela yesibili yamahedisethi azinzile, ngakho-ke i-coefficient yesisindo sesihlungi esiguqukayo izinzile. Ngakho-ke, ukuze kube lula, ama-coefficients esisindo amanye ama-headphone e-ANC abakhiqizi anqunywa efektri. Kunjalo, umuzwa wokulalela walezi zindlebe ze-ANC ngokusobala awumuhle njenge-earphone ye-ANC enencazelo yangempela eguquguqukayo, ngoba ezimeni zangempela, umsindo ovela ngaphandle uma uhlobene nesiqondiso se-earphone, izinga lokushisa elihlukile nokunye okunjalo kungaba nomthelela impendulo yesiteshi ye-earphone.
Ukuqinisekiswa kwe-Matlab
Bhala ikhodi ye-Matlab, usebenzisa isihlungi esiguquguqukayo sosayizi wesinyathelo esishintshayo se-LMS, imiphumela yokulingisa iboniswa kuMfanekiso 5. Kububanzi obungu-0 ukuya ku-2 kHz, i-ANC ehambisa phambili isetshenziselwa ukuqeda umsindo omhlophe we-Gaussian, futhi ukuncishiswa komsindo ngu-30 dB+ ngokwesilinganiso. I-FXLMS kulabhulali yeMatlab iyisinyathelo esigxilile, futhi umphumela mubi kakhulu.
Q&A
a. Kungani i-ANC inomsindo ophansi ongaphansi kuka-2 kHz kuphela?
Ngakolunye uhlangothi, ukuvaleka komsindo okungokoqobo kwama-headphone (ukunciphisa umsindo we-passive) kungavimba ngempumelelo umsindo we-high-frequency, futhi akudingekile ukusebenzisa i-ANC ukunciphisa umsindo we-high-frequency. Ngakolunye uhlangothi, umsindo we-low-frequency unobude obude futhi ungamelana nokulibaziseka kwesigaba esithile, kuyilapho umsindo we-high-frequency unobude obufushane be-wavelength futhi uzwela ekuphambukeni kwesigaba, ngakho-ke i-ANC iqeda umsindo we-high-frequency.
b. Uma ukubambezeleka kwe-elekthronikhi kukukhulu kunokulibaziseka okuyinhloko, ukusebenza kwe-algorithm kungancishiswa kanjani kakhulu?
P(z) ukubambezeleka kuncane, S(z) ukubambezeleka kukhulu, okufana no-P(z)=z-1, S(z)=z-2, kuphela uma i-W(z)=z ingahlangabezana nezimfuneko, -yimbangela, Ayifinyeleleki.
c. Uyini umehluko phakathi kwe-Feedforward ANC, i-ANC enebhendi encane, ne-feedback ANC?
Isakhiwo se-Feedforwad sinemakrofoni ye-ref kanye nemakrofoni yephutha eqoqa umsindo wangaphandle namasiginali asele angaphakathi, ngokulandelanayo. Isakhiwo sempendulo sinemakrofoni yephutha eyodwa kuphela, futhi isiginali yereferensi ikhiqizwa imakrofoni yephutha kanye nokukhishwa kwesihlungi esiguqukayo.
I-Broad-band feedforward yisakhiwo esichazwe ngenhla. Esakhiweni sebhendi encane, umthombo womsindo ukhiqiza isignali yesiginali yokucupha isignali, futhi ijeneretha yesignali ikhiqiza isignali yereferensi yesihlungi esiguquguqukayo. Kusebenza kuphela ekuqedeni umsindo wezikhathi ezithile.
Impendulo i-ANC isebenzisa imakrofoni yephutha ukubuyisela isignali eqoqwe yi-ref mic esakhiweni se-feedforward ngoba inamakrofoni wephutha kuphela. Umzila awunelisi umkhawulo we-causal, ngakho-ke izingxenye zomsindo ezibikezelwayo kuphela, okungukuthi umsindo we-narrowband periodic, ziyasuswa. Kufanele kuqashelwe ukuthi uma i-feedforward ingagculisi umkhawulo we-causal, okungukuthi ukubambezeleka kwe-elekthronikhi kude kunokulibaziseka kwesiteshi esikhulu, kungaqeda kuphela umsindo we-narrowband periodic.
Kuphinde kube nohlaka lwe-Hybrid ANC oluhlanganisa zombili izinhlaka zokuphekela kanye nezimpendulo. Inzuzo enkulu ukuthi ungagcina ukuhleleka kwesihlungi esiguquguqukayo.
