Bayyana abin da kalmomi ba za su iya bayarwa ba; jin nau'in motsin rai iri-iri da ke haɗuwa a cikin guguwar ji; su kau da kai daga doron kasa, sama har ma da ita kanta sararin duniya, ta hanyar tafiya inda babu taswira, babu hanyoyi, babu alamun; ƙirƙira, ba da labari da kuma dandana cikakken labari wanda koyaushe zai kasance na musamman kuma maras misaltuwa. Duk waɗannan ana iya yin su ta hanyar kiɗa - fasahar da ta wanzu shekaru dubbai da yawa kuma tana jin daɗin kunnuwanmu da zukatanmu.
Duk da haka, kiɗa, ko kuma wajen ayyukan kiɗa, na iya yin aiki ba kawai don jin dadi ba, amma har ma don watsa bayanan da aka sanya a cikin su, wanda aka yi nufi don wasu na'urori da ganuwa ga mai sauraro. A yau za mu saba da wani binciken da ba a saba gani ba wanda daliban da suka kammala karatun digiri daga ETH Zurich suka iya, ba tare da lura da kunnen ɗan adam ba, gabatar da wasu bayanai a cikin ayyukan kiɗa, saboda abin da kiɗan kanta ya zama tashar watsa bayanai. Ta yaya daidai yadda suka aiwatar da fasaharsu, shin waƙoƙin da suke da kuma ba tare da bayanan da aka haɗa ba sun bambanta sosai, kuma menene gwaje-gwajen aiki suka nuna? Mun koyi game da wannan daga rahoton masu binciken. Tafi
Tushen bincike
Masu binciken suna kiran fasahar watsa bayanan su ta acoustic. Lokacin da lasifika ya kunna waƙar da aka canza, mutum yana ganin ta a matsayin al'ada, amma, alal misali, wayar hannu tana iya karanta bayanan da aka ɓoye tsakanin layin, ko kuma a tsakanin bayanin kula, don magana. Masana kimiyya (kasancewar cewa wadannan mutane har yanzu daliban digiri ba ya hana su zama masana kimiyya) suna kiran sauri da amincin watsawa yayin da suke kiyaye matakin waɗannan sigogi, ba tare da la'akari da fayil ɗin da aka zaɓa ba, a matsayin mafi mahimmancin al'amari a cikin aiwatar da ayyukan. wannan dabarar canja wurin bayanai. Psychoacoustics, wanda ke nazarin ilimin tunani da ilimin lissafi na tunanin mutum game da sauti, yana taimakawa wajen jimre wa wannan aikin.
Ana iya kiran jigon watsa bayanan sauti na OFDM (orthogonal mita division multiplexing), wanda, tare da daidaita masu ɗaukar kaya zuwa kiɗan tushe na tsawon lokaci, ya ba da damar yin amfani da iyakar mitar da ake watsawa don watsa bayanai. Godiya ga wannan, yana yiwuwa a cimma saurin watsawa na 412 bps akan nisa har zuwa mita 24 (kuɗin kuskure <10%). Gwaje-gwaje na zahiri da suka haɗa da masu aikin sa kai 40 sun tabbatar da cewa kusan ba zai yuwu a ji bambanci tsakanin waƙar ta asali da wadda aka sa bayanan a ciki ba.
A ina za a iya amfani da wannan fasaha a aikace? Masu bincike suna da nasu amsar: kusan dukkanin wayoyin hannu na zamani, kwamfutar tafi-da-gidanka da sauran na'urorin hannu suna sanye da microphones, kuma yawancin wuraren jama'a (cafes, gidajen cin abinci, wuraren cin kasuwa, da dai sauransu) suna da masu magana da kiɗa na baya. Wannan waƙar bangon waya na iya, misali, haɗa bayanai don haɗawa zuwa cibiyar sadarwar Wi-Fi ba tare da buƙatar ƙarin ayyuka ba.
Babban fasali na watsa bayanan sauti sun bayyana a gare mu; yanzu bari mu matsa zuwa cikakken nazarin tsarin wannan tsarin.
Bayanin Tsarin
Gabatar da bayanai a cikin waƙar yana faruwa ne saboda yawan rufe fuska. A cikin guraben lokaci, ana gano mitoci masu rufe fuska kuma masu ɗaukar kaya na OFDM kusa da waɗannan abubuwan rufe fuska suna cike da bayanai.
Hoto #1: Maida ainihin fayil ɗin zuwa sigina mai haɗaka (waƙar waƙa + bayanai) da ake watsa ta cikin lasifika.
Da farko, siginar sauti na asali ya kasu kashi-kashi masu zuwa don bincike. Kowane irin wannan yanki (Hi) na L = 8820 samfurori, daidai da 200 ms, ana ninka ta taga* don rage tasirin iyaka.
Taga* aiki ne mai nauyi da ake amfani da shi don sarrafa tasiri saboda sidelobes a cikin ƙididdiga masu yawa.
Bayan haka, an gano manyan mitoci na siginar asali a cikin kewayon daga 500 Hz zuwa 9.8 kHz, wanda ya ba da damar samun mitoci fM, l don wannan sashin. Bugu da ƙari, an watsa bayanai a cikin ƙananan kewayon daga 9.8 zuwa 10 kHz don kafa wurin da masu ɗaukar kaya a mai karɓa. An saita iyakar iyakar mitar da aka yi amfani da ita zuwa 10 kHz saboda ƙarancin hankali na makirufonin wayar hannu a manyan mitoci.
An ƙididdige mitocin rufe fuska ga kowane yanki da aka bincika ɗaya ɗaya. Yin amfani da hanyar HPS (Harmonic Product Spectrum), an gano manyan mitoci uku sannan aka zagaya su zuwa bayanin kula mafi kusa akan ma'aunin chromatic masu jituwa. Wannan shine yadda aka sami babban bayanin fF,i = 1…3, kwance tsakanin maɓallan C0 (16.35 Hz) da B0 (30.87 Hz). Dangane da gaskiyar cewa mahimman bayanan bayanan sun yi ƙasa da amfani wajen watsa bayanai, manyan octaves 500kfF, an ƙididdige su a cikin kewayon 9.8 Hz ... 2 kHz. Yawancin waɗannan mitoci (fO,l1) sun fi fitowa fili saboda yanayin HPS.
Hoto #2: Ƙididdigar octaves fO,l1 don mahimman bayanai da jituwa fH,l2 na sautin mafi ƙarfi.
Sakamakon saitin octave da masu jituwa an yi amfani da su azaman mitoci masu rufe fuska, daga inda aka samo mitocin subcarrier OFDM fSC,k. An shigar da masu ɗaukar kaya biyu a ƙasa da sama da kowane mitar abin rufe fuska.
Bayan haka, an tace bakan sashin sauti na Hi a mitar mai ɗaukar kaya fSC,k. Bayan haka, an ƙirƙiri alamar OFDM bisa ga raƙuman bayanai a cikin Bi, wanda saboda haka ana iya watsa sashin Ci gaba ta hanyar lasifika. Dole ne a zaɓi girma da matakai na masu ɗaukar kaya ta yadda mai karɓa zai iya fitar da bayanan da aka watsa yayin da mai sauraro baya lura da canje-canje a cikin waƙar.
Hoto No. 3: ɓangaren bakan da mitoci masu ɗaukar nauyi na sashin Hi na ainihin waƙar.
Lokacin da siginar mai jiwuwa tare da bayanan da ke cikinta ke kunna ta cikin lasifika, makirufo na na'urar karba tana rikodin ta. Don nemo wuraren farawa na alamomin OFDM, da farko ana buƙatar tace bayanan rikodi. Ta wannan hanyar, ana fitar da kewayon mitoci na sama, inda babu siginonin kutsawa na kiɗa tsakanin masu ɗaukar kaya. Kuna iya nemo farkon alamun OFDM ta amfani da prefix mai zagaye.
Bayan gano farkon alamomin OFDM, mai karɓa yana samun bayanai game da mafi rinjayen bayanan kula ta hanyar ƙaddamar da yanki mai girma. Bugu da kari, OFDM yana da matukar juriya ga tushen tsangwama, tunda kawai suna shafar wasu masu jigilar kaya.
Gwaje-gwaje masu amfani
Mai magana da KRK Rokit 8 ya yi aiki a matsayin tushen karin waƙoƙin da aka gyara, kuma wayar Nexus 5X ta taka rawar mai karɓa.
Hoto #4: Bambanci tsakanin ainihin OFDM da kololuwar alaƙa da aka auna cikin gida a 5m tsakanin lasifika da makirufo.
Yawancin maki OFDM suna kwance a cikin kewayon daga 0 zuwa 25 ms, don haka zaku iya samun ingantaccen farawa a cikin prefix na 66.6 ms. Masu binciken sun lura cewa mai karɓa (a cikin wannan gwaji, wayar hannu) yana la'akari da cewa ana kunna alamun OFDM lokaci-lokaci, wanda ke inganta gano su.
Abu na farko da za a bincika shine tasirin nisa akan ƙimar kuskuren bit (BER). Don yin wannan, an gudanar da gwaje-gwaje guda uku a cikin ɗakuna daban-daban: wani corridor tare da kafet, ofishin da linoleum a ƙasa, da ɗakin taro mai katako.
An zaɓi waƙar "Kuma The Cradle Will Rock" na Van Halen a matsayin batun gwaji.
An daidaita ƙarar sautin ta yadda matakin sautin da aka auna ta wayar hannu a nesa na 2 m daga lasifikar ya kasance 63 dB.
Hoto No. 5: Alamomin BER dangane da nisa tsakanin mai magana da makirufo (layin shuɗi - masu sauraro, kore - corridor, orange - ofis).
A cikin harabar gidan, wata wayar tafi da gidanka ta ɗauki sautin 40 dB a nesa mai nisan mita 24 daga lasifikar. A cikin aji a nesa na 15 m sauti ya kasance 55 dB, kuma a cikin ofishin da ke da nisan mita 8 matakin sautin da wayar ta dauka ya kai 57 dB.
Saboda dakin taro da ofishi sun fi yin magana, ƙarshen alamar OFDM ya zarce tsayin prefix na zagaye kuma yana ƙara BER.
Fadakarwa* - raguwar ƙarfin sauti a hankali saboda yawan tunani.
Masu binciken sun kara nuna bambancin tsarin su ta hanyar amfani da shi zuwa wakoki 6 daban-daban daga nau'i uku (tebur a kasa).
Tebur No. 1: waƙoƙin da ake amfani da su a gwaji.
Har ila yau, ta hanyar bayanan tebur, za mu iya ganin ƙimar bit da kuskuren kuskure ga kowace waƙa. Adadin bayanan sun bambanta saboda bambancin BPSK (maɓallin canjin lokaci) yana aiki mafi kyau lokacin da ake amfani da masu ɗaukar kaya iri ɗaya. Kuma wannan yana yiwuwa idan sassan da ke kusa sun ƙunshi abubuwa iri ɗaya na masking. Ci gaba da ƙarar waƙoƙin suna ba da tushe mafi kyau don ɓoye bayanai saboda mitocin rufe fuska suna da ƙarfi a kan kewayon mitar mai faɗi. Kiɗa mai sauri zai iya rufe alamun OFDM kawai saboda tsayayyen tsayin taga bincike.
Bayan haka, mutane sun fara gwada tsarin, waɗanda dole ne su tantance wane irin waƙa ne na asali kuma wanda aka gyara ta hanyar bayanan da ke cikinsa. Don wannan dalili, an buga sassan waƙoƙi na daƙiƙa 12 daga tebur mai lamba 1 akan gidan yanar gizo na musamman.
A cikin gwaji na farko (E1), kowane ɗan takara an bai wa ko dai wani gyare-gyare ko guntu na asali don saurare kuma dole ne ya yanke shawara ko guntun na asali ne ko kuma an gyara shi. A gwaji na biyu (E2), mahalarta za su iya sauraron nau'ikan biyu sau da yawa kamar yadda suke so, sannan su yanke shawarar wanda ya kasance na asali da kuma wanda aka gyara.
Tebur No. 2: sakamakon gwaje-gwajen E1 da E2.
Sakamakon gwaji na farko yana da alamomi guda biyu: p(O|O) - adadin mahalarta waɗanda suka yi alama daidai waƙar ta asali da p(O|M) - yawan mahalarta waɗanda suka sanya alamar gyaran waƙar a matsayin asali.
Abin sha'awa, wasu mahalarta, a cewar masu binciken, sun ɗauki wasu waƙa da aka canza don zama mafi asali fiye da ainihin kanta. Matsakaicin gwaje-gwajen biyu suna nuna cewa matsakaicin mai sauraro ba zai lura da bambanci tsakanin waƙar waƙa ta yau da kullun da wacce aka shigar da bayanai a ciki ba.
A zahiri, ƙwararrun waƙa da mawaƙa za su iya gano wasu kurakurai da abubuwan shakku a cikin waƙoƙin da aka canza, amma waɗannan abubuwan ba su da mahimmanci don haifar da rashin jin daɗi.
Kuma yanzu mu kanmu za mu iya shiga cikin gwaji. A ƙasa akwai nau'ikan waƙa guda biyu - na asali da wanda aka gyara. Kuna iya jin bambancin?
vs
Don ƙarin cikakken sani tare da nuances na binciken, Ina ba da shawarar dubawa kungiyar bincike.
Hakanan zaka iya sauke ajiyar ZIP na fayilolin mai jiwuwa na asali da gyare-gyaren waƙoƙin da aka yi amfani da su a cikin binciken a .
Epilogue
A cikin wannan aikin, ɗaliban da suka kammala digiri daga ETH Zurich sun bayyana tsarin watsa bayanai mai ban mamaki a cikin kiɗa. Don yin wannan, sun yi amfani da abin rufe fuska na mita, wanda ya ba da damar shigar da bayanan a cikin waƙar da mai magana ya kunna. Ana gane wannan waƙar ta microphone na na'urar, wanda ke gane ɓoyayyun bayanan da kuma yanke su, yayin da matsakaicin mai sauraro ba zai lura da bambanci ba. A nan gaba, samarin suna shirin haɓaka tsarin su, tare da zaɓar ƙarin hanyoyin haɓaka bayanai don shigar da bayanai cikin sauti.
Lokacin da wani ya zo da wani abu mai ban mamaki, kuma mafi mahimmanci, wani abu da ke aiki, koyaushe muna farin ciki. Amma wani abin farin ciki shi ne cewa matasa ne suka kirkiro wannan ƙirƙira. Kimiyya ba shi da ƙuntatawa na shekaru. Kuma idan matasa suka ga ilimin kimiyya yana da ban sha'awa, to ana gabatar da shi ta hanyar kuskure, don haka a ce. Bayan haka, kamar yadda muka sani, kimiyya duniya ce mai ban mamaki da ba ta daina yin mamaki.
Ranar juma'a:
Tun da muna magana ne game da kiɗa, ko kuma kiɗan rock, ga tafiya mai ban sha'awa ta cikin sararin dutsen.
Queen, "Radio Ga Ga" (1984).
Na gode don karantawa, ku kasance da sha'awar, kuma ku sami babban mutanen karshen mako! 🙂
Na gode da kasancewa tare da mu. Kuna son labaran mu? Kuna son ganin ƙarin abun ciki mai ban sha'awa? Goyon bayan mu ta hanyar ba da oda ko ba da shawara ga abokai, Rangwamen 30% ga masu amfani da Habr akan keɓaɓɓen analogue na sabar matakin shigarwa, wanda mu muka ƙirƙira muku: (akwai tare da RAID1 da RAID10, har zuwa 24 cores kuma har zuwa 40GB DDR4).
Dell R730xd sau 2 mai rahusa? Nan kawai a cikin Netherlands! Dell R420 - 2x E5-2430 2.2Ghz 6C 128GB DDR3 2x960GB SSD 1Gbps 100TB - daga $99! Karanta game da
source: www.habr.com