Chaza amagama angenako ukugqithiswa; uzive iintlobo ezahlukeneyo zeemvakalelo ezidibeneyo kwinkanyamba yeemvakalelo; ukuba ahlukane nomhlaba, isibhakabhaka kunye neNdawo yonke ngokwayo, ehamba uhambo apho kungekho mephu, kungekho ndlela, kungekho miqondiso; yila, xelela kwaye ube namava ebali lonke eliya kuhlala likhethekile kwaye lingenakulinganiswa. Konke oku kunokwenziwa ngumculo-ubugcisa obukhoyo kangangamawaka eminyaka kwaye buyolisa iindlebe neentliziyo zethu.
Nangona kunjalo, umculo, okanye kunoko imisebenzi yomculo, inokusebenza kungekuphela nje kulonwabo lobuhle, kodwa kunye nokuhanjiswa kolwazi olufakwe kuyo, olulungiselelwe isixhobo esithile kwaye lungabonakali kumphulaphuli. Namhlanje siza kuqhelana nesifundo esingaqhelekanga kakhulu apho abafundi abaphumelele kwi-ETH Zurich babekwazi, bengakhange baqatshelwe yindlebe yomntu, ukwazisa idatha ethile kwimisebenzi yomculo, ngenxa yokuba umculo ngokwawo uba ngumjelo wokudlulisa idatha. Baye baphumeza njani kanye itekhnoloji yabo, ngaba iingoma ezineedatha ezizinzisiweyo zahluke kakhulu, kwaye uvavanyo olusebenzayo lwabonisa ntoni? Sifunda malunga noku kwingxelo yabaphandi. Hamba.
Isiseko sophando
Abaphandi babiza itekhnoloji yabo yetekhnoloji yokuhambisa idatha ye-acoustic. Xa isithethi sidlala ingoma eguquliweyo, umntu uyayibona njengento eqhelekileyo, kodwa, umzekelo, i-smartphone inokufunda ulwazi olufakwe kwikhowudi phakathi kwemigca, okanye kunoko phakathi kwamanqaku, ngoko kuthetha. Izazinzulu (inyaniso yokuba aba bafana basengabafundi abaphumeleleyo ayibathinteli ekubeni babe zizazinzulu) biza isantya kunye nokuthembeka kosasazo ngelixa ugcina inqanaba lezi parameters, kungakhathaliseki ukuba ifayile yeaudio ekhethiweyo, njengeyona nkalo ibalulekileyo ekuphunyezweni kwe obu buchule bokudlulisa idatha. I-Psychoacoustics, ephonononga imiba yengqondo kunye neyomzimba yombono womntu wezandi, inceda ukujamelana nalo msebenzi.
Undoqo wokuhanjiswa kwedatha ye-acoustic inokubizwa ngokuba yi-OFDM (i-orthogonal frequency division multiplexing), eyathi, kunye nokulungelelaniswa kwe-subcarriers kumculo womthombo ngokuhamba kwexesha, yenze ukuba kube lula ukusebenzisa i-spectrum yefrikhwensi yokuhanjiswa kolwazi. Ndiyabulela kule nto, kwakunokwenzeka ukufezekisa isantya sokuhanjiswa kwe-412 bps kumgama ukuya kwi-24 yeemitha (izinga lempazamo <10%). Uvavanyo olusebenzisekayo olubandakanya amatsha-ntliziyo angama-40 lwaqinisekisa isibakala sokuba phantse akunakwenzeka ukuva umahluko phakathi kwesandi somculo santlandlolo naleyo nkcazelo yayifakwe kuyo.
Le teknoloji ingasetyenziswa phi ekusebenzeni? Abaphandi banempendulo yabo: phantse zonke ii-smartphones zanamhlanje, ii-laptops kunye nezinye izixhobo eziphathwayo zixhotyiswe ngeemakrofoni, kunye neendawo ezininzi zoluntu (iikhefi, iivenkile zokutyela, iindawo zokuthenga, njl. njl.) zinezithethi ezinomculo ongasemva. Le ngoma yangasemva inokuthi, umzekelo, ibandakanye idatha yokuqhagamshela kwinethiwekhi ye-Wi-Fi ngaphandle kwesidingo seentshukumo ezongezelelweyo.
Iimpawu eziqhelekileyo zokuhanjiswa kwedatha ye-acoustic ziye zacaca kuthi; ngoku makhe siqhubele phambili kwisifundo esicacileyo sokwakheka kwale nkqubo.
Inkcazo yeNkqubo
Ukungeniswa kwedatha kumculo wengoma kwenzeka ngenxa yokugquma amaza. Ngexesha lokubeka, i-masking frequencies ichongiwe kwaye ii-OFDM subcarriers ezikufutshane nezi zinto zokugquma zizaliswe ngedatha.
Umfanekiso #1: Ukuguqula ifayile yokuqala ibe ngumqondiso odibeneyo (ingoma + yedatha) ehanjiswa ngezithethi.
Ukuqala, isibonakaliso sokuqala somsindo sahlulwe sibe ngamacandelo alandelelanayo ukuze kuhlalutywe. Icandelo ngalinye elinjalo (Hi) le-L = 8820 iisampulu, elilingana nama-200 ms, liphindaphindwa nge ifestile* ukunciphisa iziphumo zomda.
Ifestile* ngumsebenzi wobunzima osetyenziselwa ukulawula iziphumo ngenxa ye-sidelobes kuqikelelo lwe-spectral.
Okulandelayo, ii-frequencies eziphambili zesignali yokuqala zifunyenwe kuluhlu ukusuka kwi-500 Hz ukuya kwi-9.8 kHz, eyenze ukuba kube lula ukufumana i-masking frequencies fM, l kweli candelo. Ukongezelela, idatha idluliselwe kuluhlu oluncinci ukusuka kwi-9.8 ukuya kwi-10 kHz ukuseka indawo ye-subcarriers kwi-receiver. Umda ophezulu woluhlu lwamaza okusetyenziswa lubekwe kwi-10 kHz ngenxa yobuthathaka obuphantsi beemakrofoni ze-smartphone kwiifrikhwensi eziphezulu.
Iifrikhwensi zokufihla zamiselwa kwicandelo ngalinye elihlalutyiweyo ngabanye. Ukusebenzisa indlela ye-HPS (Harmonic Product Spectrum), iifrikhwensi ezintathu ezilawulayo zichongiwe kwaye emva koko zijikelezwe kumanqaku akufutshane kwi-harmonic chromatic scale. Le yindlela amanqaku aphambili e-fF, i = 1β¦3 afunyenwe ngayo, elele phakathi kwezitshixo ze-C0 (16.35 Hz) kunye ne-B0 (30.87 Hz). Ngokusekwe kwinto yokuba amanqaku asisiseko aphantsi kakhulu ukuba angasetyenziselwa ukuhanjiswa kwedatha, ii-octave zabo eziphezulu 500kfF,i zibalwe kuluhlu lwe-9.8 Hz ... 2 kHz. Uninzi lwezi zihlandlo (fO,l1) zaye zacaca ngakumbi ngenxa yobume be-HPS.
Umfanekiso #2: Ii-octaves ezibaliweyo ze-O,l1 zamanqaku asisiseko kunye neeharmonics fH,l2 yethoni eyomeleleyo.
Iseti yesiphumo yee-octave kunye nee-harmonics zasetyenziswa njengezakheko zokufihla, apho i-OFDM ye-subcarrier frequency fSC,k yafunyanwa. Ii-subcarriers ezimbini zifakwe ngezantsi kwaye ngaphezu kwefrikhwensi nganye yokufihla.
Okulandelayo, i-spectrum yecandelo le-audio ye-Hi yahluzwa kwii-fSC, k. Emva koko, isimboli ye-OFDM yadalwa ngokusekwe kulwazi lwamasuntswana kwi-Bi, ngenxa yokuba icandelo elihlanganisiweyo le-Ci linokuhanjiswa ngesithethi. Ubukhulu kunye nezigaba ze-subcarriers kufuneka zikhethwe ukwenzela ukuba umamkeli akhuphe idatha edlulisiweyo ngelixa umphulaphuli engaboni utshintsho kwingoma.
Umfanekiso we-3: inxalenye ye-spectrum kunye ne-subcarrier frequencies ye-Hi segment yomculo wokuqala.
Xa isignali ye-audio eneenkcukacha ezikhowudwe kuyo idlalwa ngezithethi, i-microphone yesixhobo esiyifumanayo iyayirekhoda. Ukufumana izithuba zokuqalisa zeesimboli ezizinzisiweyo zeOFDM, iirekhodi kufuneka kuqala zihluzwe i-bandpass. Ngale ndlela, uluhlu oluphezulu lwefrikhwensi lukhutshwe, apho kungekho zibonakaliso zokuphazamiseka komculo phakathi kwee-subcarriers. Ungafumana isiqalo seesimboli zeOFDM usebenzisa isimaphambili somjikelo.
Emva kokubona ukuqalisa kweesimboli ze-OFDM, umamkeli ufumana ulwazi malunga namanqaku abalaseleyo ngokudityaniswa kwe-domain ephezulu. Ukongeza, i-OFDM ixhathisa kakhulu kwimithombo yokuphazamiseka kwe-narrowband, kuba ichaphazela kuphela ezinye zee-subcarriers.
Iimvavanyo ezisebenzayo
Isithethi se-KRK Rokit 8 sisebenze njengomthombo weengoma ezilungisiweyo, kwaye i-Nexus 5X ye-smartphone idlale indima yeqela elifumanayo.
Umfanekiso #4: Umahluko phakathi kwe-OFDM yokwenyani kunye neencopho zolungelelwaniso ezilinganiswe ngaphakathi kwi-5m phakathi kwesithethi kunye nemakrofoni.
Uninzi lwamanqaku e-OFDM alele kuluhlu ukusuka ku-0 ukuya ku-25 ms, ukuze ufumane isiqalo esisebenzayo ngaphakathi kwe-66.6 ms cyclic prefix. Abaphandi baqaphela ukuba umamkeli (kolu vavanyo, i-smartphone) ithathela ingqalelo ukuba iisimboli ze-OFDM zidlalwa ngamaxesha athile, okuphucula ukubonwa kwazo.
Into yokuqala ekufuneka iqwalaselwe yayisisiphumo somgama kwisantya sempazamo encinci (BER). Ukwenza oku, iimvavanyo ezintathu zenziwa kwiindidi ezahlukeneyo zamagumbi: i-corridor enekhaphethi, iofisi ene-linoleum phantsi, kunye neholo elinomgangatho womthi.
Ingoma ethi "Kwaye iCradle Will Rock" kaVan Halen yakhethwa njengesifundo sovavanyo.
Umthamo wesandi uhlengahlengiswe ukwenzela ukuba inqanaba lesandi elilinganiswe yi-smartphone kumgama we-2 m ukusuka kwisithethi ngu-63 dB.
Umfanekiso we-5: Iimpawu ze-BER kuxhomekeke kumgama phakathi kwesithethi kunye nemakrofoni (umgca ohlaza okwesibhakabhaka - abaphulaphuli, uhlaza - i-corridor, i-orange-ofisi).
Epasejini, isandi se-40 dB sathathwa yi-smartphone kumgama ofikelela kuma-24 eemitha ukusuka kwisithethi. Eklasini kumgama we-15 m isandi sasiyi-55 dB, kwaye kwiofisi kumgama weemitha ezi-8 inqanaba lesandi elibonwa yi-smartphone lifikelele kwi-57 dB.
Ngenxa yokuba i-auditorium kunye ne-ofisi ziphindaphindeka ngakumbi, i-echoes yesimboli ye-OFDM kade idlula ubude besimaphambili somjikelo kwaye inyuse iBER.
Reverberation* - Ukwehla kancinci koxinzelelo lwesandi ngenxa yokubonakalisa okuninzi.
Abaphandi babonisa ngakumbi ukuguquguquka kwenkqubo yabo ngokuyisebenzisa kwiingoma ezahlukeneyo ze-6 ezivela kwiintlobo ezintathu (itheyibhile engezantsi).
Itheyibhile ye-1: iingoma ezisetyenziswa kwiimvavanyo.
Kwakhona, ngedatha yetafile, sinokubona umlinganiselo webit kunye namazinga empazamo encinci kwingoma nganye. Iireyithi zedatha ziyahluka ngenxa yokuba i-BPSK eyahlukileyo (i-phase shift keying) isebenza ngcono xa kusetyenziswa i-subcarriers efanayo. Kwaye oku kunokwenzeka xa amacandelo akufutshane aqulethe izinto ezifanayo zokufihla. Iingoma ezingxolayo eziqhubekayo zibonelela ngesiseko esisiso sokufihla idatha kuba iifrikhwensi zokufihla zikho ngamandla ngakumbi kuluhlu olubanzi lwamaza. Umculo okhawulezayo unokuvala ngokuyinxenye iisimboli ze-OFDM ngenxa yobude obumiselweyo befestile yokuhlalutya.
Emva koko, abantu baqalisa ukuyivavanya inkqubo, ekwakufuneka bagqibe ukuba yeyiphi ingoma eyayiyeyoqobo neyayitshintshwa lulwazi olufakwe kuyo. Ngenxa yale njongo, iicatshulwa ze-12-yesibini yeengoma ezivela kwitheyibhile yeNombolo ye-1 zifakwe kwiwebhusayithi ekhethekileyo.
Kuvavanyo lokuqala (E1), umthathi-nxaxheba ngamnye wanikwa iqhekeza eliguquliweyo okanye lentsusa yokuphulaphula kwaye kwafuneka athathe isigqibo sokuba ingaba isiqwenga sasiyintsusa okanye silungisiwe. Kuvavanyo lwesibini (E2), abathathi-nxaxheba banokumamela zombini iinguqulelo kaninzi njengoko befuna, baze bathathe isigqibo sokuba yeyiphi eyentsusa kwaye yeyiphi elungisiweyo.
Itheyibhile ye-2: iziphumo zovavanyo lwe-E1 kunye ne-E2.
Iziphumo zovavanyo lokuqala zinezalathi ezibini: p(O|O) - ipesenteji yabathathi-nxaxheba abamakisha ngokuchanekileyo ingoma yoqobo kunye no-p(O|M) - ipesenti yabathathi-nxaxheba abamakishe inguqulelo elungisiweyo yomculo njengentsusa.
Okubangela umdla kukuba, abanye abathathi-nxaxheba, ngokutsho kwabaphandi, bathathela ingqalelo iingoma ezithile ezitshintshiweyo njengezokuqala kunezokuqala ngokwazo. Umndilili weemvavanyo zombini ucebisa ukuba umphulaphuli ophakathi akanakuqaphela umahluko phakathi komculo oqhelekileyo kunye nenye apho idatha ifakwe khona.
Ngokwemvelo, iingcali zomculo kunye neemvumi ziya kukwazi ukubona ezinye izinto ezingachanekanga kunye nezinto ezikrokrelayo kwiingoma ezitshintshiweyo, kodwa ezi zinto azibalulekanga kangangokuba zingabangela ukungonwabi.
Kwaye ngoku nathi sinokuthatha inxaxheba kuvavanyo. Apha ngezantsi kukho iinguqulelo ezimbini zomculo ofanayo - owokuqala kunye nowolunye uhlengahlengiso. Uyawuva umahluko?
vs
Ukuze ufumane ulwazi oluthe kratya malunga nee-nuances zophononongo, ndincoma ukujonga iqela lophando.
Unako kwakhona ukukhuphela indawo yokugcina ye-ZIP yeefayile ezimanyelwayo zoqobo kunye neengoma ezilungisiweyo ezisetyenziswe kuphononongo .
Ipilo
Kulo msebenzi, abafundi abaphumelele kwi-ETH Zurich bachaze inkqubo yokuhanjiswa kwedatha emangalisayo ngaphakathi komculo. Ukwenza oku, basebenzise imaski yokuphindaphinda, nto leyo eyenza kube lula ukubethelela idatha kumculo odlalwa sisithethi. Lo mculo ubonwa ngumbhobho wesixhobo, oqaphela idatha efihliweyo kwaye uyichaze, ngelixa umphulaphuli oqhelekileyo akayi kuwubona umahluko. Kwixesha elizayo, abafana baceba ukuphuhlisa inkqubo yabo, bekhetha iindlela eziphambili zokwazisa idatha kwi-audio.
Xa umntu eza nento engaqhelekanga, kwaye okona kubaluleke kakhulu, into esebenzayo, sihlala sivuya. Kodwa eyona nto ivuyisayo kukuba le nto yenziwa ngabantu abaselula. Inzululwazi ayinazithintelo zobudala. Yaye ukuba abantu abaselula bayifumanisa inzululwazi ikruqula, ngoko ke ichazwa ngendlela engafanelekanga. Ngapha koko, njengoko sisazi, inzululwazi lihlabathi elimangalisayo elingayeki ukumangalisa.
NgoLwesihlanu ukusuka phezulu:
Kuba sithetha ngomculo, okanye kunoko umculo we-rock, nalu uhambo olumnandi kwi-expanses ye-rock.
UKumkanikazi, "iRadio Ga Ga" (1984).
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