1) Ikhodi ye-AMI
Igama eligcwele lekhodi ye-AMI (Alternative Mark Inversion) enye ikhodi yokuguqula uphawu. blank) ihlala ingashintshiwe. Isb:
Ikhodi yomlayezo: 0 1 1 0 0 0 0 0 0 0 1 1 0 0 1 1…
Ikhodi ye-AMI: 0 -1 +1 0 0 0 0 0 0 0 0 -1 +1 0 0 -1 +1...
I-waveform ehambisana nekhodi ye-AMI iwukulandelana kwe-pulse enamazinga avumayo, angalungile, kanye neziro. Kungabhekwa njengokuwohloka kwe-unipolar waveform, okungukuthi, “0″ isahambisana nezinga elinguziro, kuyilapho u-“1” ehambisana namaleveli avumayo noma angalungile ngokushintshana.
Inzuzo yekhodi ye-AMI ukuthi ayikho ingxenye ye-DC, kunezingxenye ezimbalwa eziphezulu neziphansi, futhi amandla agxilwe ku-frequency ye-1/2 yekhodi yesivinini.
(Umdwebo 6-4); Isifunda se-codec silula, futhi i-polarity yekhodi ingasetshenziswa ukubuka isimo sephutha; uma kuyi-waveform ye-AMI-RZ, ingashintshwa ibe yi-unipolar inqobo nje uma isalungiswa igagasi eligcwele ngemva kokuyithola. I-waveform ye-RZ lapho izingxenye zesikhathi esincane zingakhishwa khona. Ngenxa yalezi zinzuzo ezingenhla, ikhodi ye-AMI isiphenduke enye yezinhlobo zamakhodi okudlulisela asetshenziswa kakhulu.
Ububi bekhodi ye-AMI: Uma ikhodi yoqobo inochungechunge olude lwe-“0″, ileveli yesiginali ayigxumi isikhathi eside, okwenza kube nzima ukukhipha isignali yesikhathi. Enye yezindlela ezisebenzayo zokuxazulula inkinga yekhodi ethi “0″ ukusebenzisa ikhodi ye-HDB3.
(2) Ikhodi ye-HDB3
Igama eligcwele lekhodi ye-HDB3 yikhodi yesithathu ye-high-density bipolar. Iwuhlobo oluthuthukisiwe lwekhodi ye-AMI. Inhloso yokuthuthukisa ukugcina okuhle kwekhodi ye-AMI futhi kunqobe ukushiyeka kwayo ukuze inani lama-“0” alandelanayo lingeqi kokuthathu. Imithetho yayo yokufaka ikhodi imi kanje:
Qala uhlole inombolo yo-“0” elandelanayo kukhodi yomlayezo. Uma inombolo elandelanayo ethi “0″s ingaphansi noma ilingana no-3, iyafana nomthetho wombhalo wekhodi wekhodi ye-AMI. Uma inombolo ethi “0” elandelanayo idlula oku-3, okuthi “0” ngakunye kwezingu-4 ezilandelanayo zizoguqulelwa zibe yisigaba futhi kufakwe okuthi “000V” esikhundleni. I-V (inani elingu-+1 noma -1) kufanele libe ne-polarity efanayo neyandulela ishayela eliseduze elingeyona-”0″ (ngoba lokhu kwephula umthetho wokushintshana kwe-polarity, ngakho-ke u-V ubizwa ngokuthi ukushaya kwenhliziyo okubhubhisayo). Izimpawu ezisondelene zekhodi ye-V kufanele zishintshane. Uma inani lekhodi engu-V lingakwazi ukuhlangabezana nezimfuneko kokuthi (2) kodwa lingakwazi ukuhlangabezana nale mfuneko, shintsha okuthi “0000″ ngokuthi “B00V”. Inani lika-B lihambisana ne-V pulse elandelayo ukuxazulula le nkinga. Ngakho-ke, u-B ubizwa ngokuthi i-modulation pulse. I-polarity yenombolo yokudlulisela ngemva kwekhodi engu-V nayo kufanele ishintshwe.
Ngokungeziwe ezinhlelweni zekhodi ye-AMI, ikhodi ye-HDB3 iphinda ikhawulele inani lamakhodi alandelanayo “0″ ngaphansi kuka-3, ukuze ukukhishwa kolwazi lwesikhathi kuqinisekiswe ngesikhathi sokwamukela. Ngakho-ke, ikhodi ye-HDB3 iwuhlobo lwekhodi olusetshenziswa kakhulu ezweni lami naseYurophu, futhi izinhlobo zekhodi yesixhumi esibonakalayo ngezansi kweqembu le-A-law PCM quaternary zonke zingamakhodi e-HDB3.
Ekhodini ye-AMI eshiwo ngenhla kanye nekhodi ye-HDB3, ikhodi ngayinye kanambambili iguqulwa ibe ikhodi enenani elingu-1-bit lamazinga amathathu (+1, 0, -1), ngakho lolu hlobo lwekhodi lubizwa nangokuthi ikhodi engu-1B1T. Ngaphezu kwalokho, kungenzeka futhi ukuklama ikhodi ye-HDBn lapho inani elithi “0″s lingeqi ku-n.
(3) Ikhodi ye-Biphase
Ikhodi ye-Biphase ibizwa nangokuthi ikhodi yaseManchester. Isebenzisa isikhathi samagagasi ayisikwele avumayo kanye nebi ukumela u-“0” kanye ne-waveform yayo ephambene ukuze imele u-“1″. Omunye wemithetho yombhalo wekhodi ukuthi "0" ikhodi imelwe "01" ikhodi enamadijithi amabili, futhi "1" ikhodi imelwe "10" ikhodi enamadijithi amabili. Ngokwesibonelo,
Inombolo yomlayezo: 1 1 0 0 1 0 1
Ikhodi ye-Biphase: 10 10 01 01 10 01 10
I-biphasic code waveform iyi-bipolar NRZ waveform enamazinga amabili kuphela e-polarity ephambene. Ineleveli yokweqa endaweni emaphakathi yesikhawu sophawu ngalunye, ngakho iqukethe ulwazi olucebile lwesikhathi. Ayikho ingxenye ye-DC, futhi inqubo yokufaka ikhodi nayo ilula. Okubi ukuthi umkhawulokudonsa othathiwe uphindwe kabili, okunciphisa izinga lokusetshenziswa kwebhendi yefrikhwensi. Ikhodi yesigaba se-bi-phase ilungile ekuthumeleni okokusebenza kwetheminali yedatha ebangeni elifushane, futhi ivamise ukusetshenziswa njengohlobo lwekhodi yokudlulisela kunethiwekhi yendawo.
(4) Ikhodi yokuhlukanisa izigaba ezimbili
Ukuze kuxazululwe iphutha lokukhipha amakhodi elibangelwe ukuhlehla kwe-polarity kwekhodi yesigaba se-bi, umqondo wekhodi yokuhlukanisa ungasetshenziswa. Ikhodi ye-Biphase isebenzisa ukuguqulwa kweleveli emaphakathi nesikhathi sophawu ngalunye lokuvumelanisa kanye nokumelwa kwekhodi yezimpawu (ushintsho olusuka kokunegethivu ukuya kokuphozithivu lumelela kanambambili “0″, futhi ukuguquka ukusuka kokuphozithivu kuya kokunegethivu kumelela kanambambili “1″). Ekukhodinini kwekhodi ye-biphase ehlukile, ukuguqulwa kwezinga phakathi kophawu ngalunye kusetshenziselwa ukuvumelanisa, futhi noma ngabe kunoshintsho olwengeziwe ekuqaleni kophawu ngalunye lusetshenziselwa ukunquma ikhodi yesignali. Uma kukhona uguquko, kusho kanambambili “1″, futhi uma lungekho uguquko, kusho kanambambili “0”. Le khodi ivame ukusetshenziswa kumanethiwekhi endawo.
Ikhodi ye-CMI
Ikhodi ye-CMI isifinyezo esithi “mark inversion code. Njengekhodi ye-bi-phase, iphinde ibe ikhodi enamazinga amabili e-bipolar. Umthetho wokubhala ngekhodi uthi: “1″ ikhodi imelwa ngokushintshana ngokuthi “11” kanye “00” nekhodi enezinombolo ezimbili; ikhodi ethi “0″ imelelwe ngokuqinile ngu-“01″, futhi i-waveform yayo iboniswa kuMfanekiso 6-5(c).
Amakhodi e-CMI kulula ukuwasebenzisa futhi aqukethe ulwazi olucebile lwesikhathi. Ngaphezu kwalokho, njengoba i-10 iyiqembu lamakhodi enqatshelwe, ngeke kube namakhodi angaphezu kwamathathu alandelanayo, futhi lo mthetho ungasetshenziselwa ukutholwa kwephutha elikhulu. Le khodi inconywe i-ITU-T njengohlobo lwekhodi yesixhumi esibonakalayo yequartet ye-PCM futhi ngezinye izikhathi isetshenziswa ezinhlelweni zokudlulisa ikhebula elikhanyayo ngenani elingaphansi kuka-8.448Mb/s.
Vimba umbhalo wekhodi
Ukuze kuthuthukiswe ukusebenza kwekhodi yomugqa, uhlobo oluthile lokuphinda ludingeke ukuze kuqinisekiswe ukuvumelanisa kwephethini nokutholwa kwamaphutha. Ukwethulwa kwekhodi yebhulokhi kungafeza zombili lezi zinhloso ngokwezinga elithile. Uhlobo lwekhodi yebhulokhi yikhodi ye-nBmB, ikhodi ye-nBmT nokunye.
Ikhodi ye-nBmB iwuhlobo lwekhodi yebhulokhi, ehlukanisa ikhodi kanambambili ye-n-bit yokusakaza kolwazi lwangempela ibe yiqembu futhi esikhundleni sayo ifake iqembu lekhodi elisha lekhodi kanambambili ye-m-bit, lapho m>n. Kusukela ku-m>n, iqembu lekhodi elisha lingase libe Kukhona izinhlanganisela ezingu-2^m, ngakho-ke kunezinhlanganisela ezengeziwe (2^m-2^n). Phakathi kwezinhlanganisela ezingu-2″, iqembu lamakhodi elivumayo likhethwa ngandlela thize njengeqembu lekhodi elivunyelwe, kanti okunye kusetshenziswa njengeqembu lamakhodi enqatshelwe ukuze kutholwe ukusebenza okuhle kokufakwa kwamakhodi. Isibonelo, ekufakweni kwekhodi kwe-4B5B, kusetshenziswa ikhodi engu-5-bit esikhundleni sekhodi engu-4-bit. Ukubhala amakhodi, kweqoqo le-4-bit, kukhona kuphela 2^4=16 inhlanganisela ehlukene, futhi ekuhlanganiseni kwe-5-bit, kukhona 2^5=32 izinhlanganisela ezihlukene. Ukuze sifinyelele ukuvumelanisa, asikwazi ukulandela okungaphezu kokukodwa okuholayo okuthi “0″ nezijobelelo Ezimbili “0” zisetshenziselwa ukukhetha amaqembu ekhodi, futhi amanye amaqembu ekhodi akhutshaziwe. Ngale ndlela, uma iqembu lekhodi ekhubazekile livela ekugcineni kokwamukela, kusho ukuthi kunephutha enqubweni yokudlulisela, ngaleyo ndlela kuthuthukiswe ikhono lokuthola iphutha lesistimu. Womabili amakhodi e-bi-phase namakhodi e-CMI angathathwa njengamakhodi angu-1B2B.
Ohlelweni lokuxhumana lwefiber optical, m=n+1 kuvame ukukhethwa, bese kuthathwa ikhodi ethi 1B2B, 2B3B code, 3B4B code kanye ne5B6B code. Phakathi kwazo, iphethini yekhodi engu-5B6B isetshenziswe ngokwesibonelo njengephethini yekhodi yokudlulisela ngomugqa yeqembu lesithathu neqembu lesine noma ngaphezulu.
Ikhodi ye-nBmB inikeza ukuvumelanisa okuhle nemisebenzi yokuthola amaphutha, kodwa futhi ikhokha inani elithile, okungukuthi, umkhawulokudonsa odingekayo ukhuphuka ngokufanele.
Umqondo wokuklama wekhodi ye-nBmT ukuguqula amakhodi kanambambili abe yiqembu elisha lamakhodi e-m ternary, kanye no-m.
Okungenhla kuyincazelo yamaphuzu olwazi "Izinhlobo Zekhodi Ezivamile Zokudluliselwa Kwe-Baseband" ezilethwe kuwe yi-Shenzhen Hi-Diwei Optoelectronics Technology Co., Ltd., ngithemba ukuthi lesi sihloko singakusiza ukukhulisa ulwazi lwakho. Ngaphandle kwalesi sihloko uma ufuna inkampani enhle yabakhiqizi bemishini yokuxhumana ye-fiber ongase uyicabangeleMayelana NATHI.
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