1) Kode ya AMI
Izina ryuzuye rya kode ya AMI (Ubundi buryo bwa Mark Inversion) ni kode isimburana kode. ubusa) guma idahindutse. Urugero:
Kode yubutumwa: 0 1 1 0 0 0 0 0 0 0 0 1 1 0 0 1 1…
Kode ya AMI: 0 -1 +1 0 0 0 0 0 0 0 0 -1 +1 0 0 -1 + 1…
Umuhengeri uhuye na code ya AMI ni pulse ikurikirana hamwe nibyiza, bibi, na zeru. Irashobora gufatwa nkuguhindura imiterere ya unipolar waveform, ni ukuvuga, "0 ″ iracyahuye nurwego rwa zeru, mugihe" 1 ″ ihuye nurwego rwiza kandi rubi muburyo butandukanye.
Ibyiza bya kode ya AMI nuko nta kintu cya DC kirimo, hariho ibice bike byo hejuru kandi biciriritse-buke, kandi ingufu zikaba zibanda kumurongo wa 1/2 kode yihuta.
(Isanamu 6-4); Inzira ya codec iroroshye, kandi code polarite irashobora gukoreshwa mukureba ikibazo cyamakosa; niba ari imiyoboro ya AMI-RZ, irashobora guhinduka kuri unipolar mugihe cyose yuzuye-yuzuye ikosowe nyuma yo kwakira. RZ waveform ivamo ibice bito byigihe bishobora gukurwamo. Kubera inyungu zavuzwe haruguru, code ya AMI yabaye imwe muburyo bukoreshwa muburyo bwo kohereza.
Ibibi bya code ya AMI: Iyo code yumwimerere ifite urukurikirane rurerure rwa “0 ″, urwego rwikimenyetso ntirusimbuka umwanya muremure, bigatuma bigora gukuramo ibimenyetso byigihe. Bumwe mu buryo bwiza bwo gukemura ikibazo cy '“0 ″ code ni ugukoresha code ya HDB3.
(2) Kode ya HDB3
Izina ryuzuye rya code ya HDB3 nisoko rya gatatu-ryuzuye-bipolar code. Nubwoko bunoze bwa code ya AMI. Intego yo kunoza ni ugukomeza ibyiza bya code ya AMI no gutsinda ibitagenda neza kugirango umubare wikurikiranya “0 ″ s utarenza eshatu. Amategeko ya kodegisi yayo ni aya akurikira:
Banza urebe umubare wikurikiranya "0 ″ s mukurikirana ubutumwa. Iyo umubare wikurikiranya "0 ″ s uri munsi cyangwa uhwanye na 3, ni kimwe n amategeko agenga kodegisi ya AMI. Iyo umubare wikurikiranya "0 ″ s urenze 3, buri kimwe muri 4 gikurikiranye" 0 ″ s kizahindurwa igice hanyuma gisimburwe na "000V". V. V-code yegeranye igomba guhinduranya. Iyo agaciro ka kode ya V gashobora kuzuza ibisabwa muri (2) ariko ntigashobora kuzuza iki gisabwa, hanyuma usimbuze “0000 ″ na“ B00V ”. Agaciro ka B gahuye na V pulse ikurikira kugirango iki kibazo gikemuke. Kubwibyo, B yitwa modulation pulse. Uburinganire bwimibare yoherejwe nyuma ya V code nayo igomba guhinduranya.
Usibye ibyiza bya code ya AMI, code ya HDB3 inagabanya umubare wikurikiranya "0 ″ kode ikurikiranye kugeza munsi ya 3, kugirango gukuramo amakuru yigihe bishobora kwizerwa mugihe cyo kwiyakira. Kubwibyo, code ya HDB3 nubwoko bukoreshwa cyane mugihugu cyanjye no muburayi, kandi ubwoko bwimyandikire yimbere munsi ya A-amategeko PCM quaternary group yose ni code ya HDB3.
Muri kode ya AMI yavuzwe haruguru hamwe na kode ya HDB3, buri kode ya binary ihindurwamo kode ifite agaciro ka 1-biti yo mu rwego rwa gatatu (+1, 0, -1), ubwo rero kode nayo yitwa 1B1T code. Mubyongeyeho, birashoboka kandi gukora code ya HDBn aho umubare wa “0 ″ s utarenze n.
(3) Kode ya Biphase
Kode ya Biphase nayo yitwa code ya Manchester. Ikoresha igihe cyiza kandi kibi cya simmetrike ya kwadrateri yerekana “0 ″ hamwe nu murongo wacyo ugereranya“ 1 ″. Rimwe mu mategeko agenga kodegisi ni uko “0 ″ code ihagarariwe na“ 01 ″ kode y'imibare ibiri, naho “1 ″ code igereranwa na“ 10 ″ kode y'imibare ibiri. Kurugero,
Kode yubutumwa: 1 1 0 0 1 0 1
Kode ya Biphase: 10 10 01 01 10 01 10
Biphasic code waveform ni bipolar NRZ yumurongo hamwe ninzego ebyiri gusa zinyuranye za polarite. Ifite urwego rusimbuka kuri point point ya buri kimenyetso intera, bityo ikubiyemo ibintu bito bito byigihe. Nta kintu cya DC kirimo, kandi inzira ya kodegisi nayo iroroshye. Ingaruka ni uko umurongo wagutse wikubye kabiri, bigabanya igipimo cyo gukoresha umurongo wa radiyo. Kode ya bi-fase ninziza yo kohereza amakuru ya terefone yanyuma intera ndende, kandi ikoreshwa kenshi nkubwoko bwa code yoherejwe mumurongo waho.
(4) Kode y'ibyiciro bibiri bitandukanye
Kugirango ukemure ikosa rya decoding ryatewe na polarite ihindagurika ya bi-fase code, igitekerezo cya code zitandukanye kirashobora gukoreshwa. Kode ya Biphase ikoresha urwego rwinzibacyuho hagati yigihe cyigihe cya buri kimenyetso cyo guhuza no kwerekana ibimenyetso byerekana kode (inzibacyuho kuva mubyiza ikagera kuri positif igereranya binary “0 ″, naho guhinduka kuva mubyiza ukajya mubi byerekana binary“ 1 ″). Mu buryo butandukanye biphase code code, urwego rwinzibacyuho rwagati muri buri kimenyetso rukoreshwa muguhuza, kandi niba hari inzibacyuho yinyongera mugitangiriro cya buri kimenyetso ikoreshwa mukumenya kode yikimenyetso. Niba hari inzibacyuho, bisobanura binary “1 ″, kandi niba nta nzibacyuho, bisobanura binary“ 0 ″. Iyi code ikoreshwa kenshi murusobe rwakarere.
Kode ya CMI
Kode ya CMI ni impfunyapfunyo ya “marike inversion code. Kimwe na bi-cyiciro kode, nayo ni bipolar ebyiri-code. Amategeko ya code ni: “1 ″ kode igereranwa na“ 11 ″ na “00 ″ kode y'imibare ibiri; “0 ″ code igaragazwa neza na“ 01 ″, kandi imiterere yayo yerekana ishusho ya 6-5 (c).
Kode ya CMI iroroshye kuyishyira mubikorwa kandi ikubiyemo amakuru akungahaye. Mubyongeyeho, kubera ko 10 ari kode yabujijwe itsinda, ntihazabaho kode zirenze eshatu zikurikiranye, kandi iri tegeko rishobora gukoreshwa mugutahura amakosa ya macroscopique. Iyi code yasabwe na ITU-T nkubwoko bwimiterere yimiterere ya quartet ya PCM kandi rimwe na rimwe ikoreshwa muri sisitemu yohereza insinga ya optique ifite igipimo kiri munsi ya 8.448Mb / s.
Hagarika kodegisi
Kunoza imikorere ya coding imikorere, ubwoko bumwe bwikirenga burasabwa kugirango habeho guhuza no guhuza amakosa. Intangiriro yo guhagarika code irashobora kugera kuri izi ntego zombi kurwego runaka. Imiterere yo guhagarika code ni nBmB code, nBmT code nibindi.
nBmB code ni ubwoko bwa coding ya blok, igabanya n-bit binary code yamakuru yumwimerere amakuru mumatsinda hanyuma ikayasimbuza itsinda rishya rya kode ya m-bit binary code, aho m> n. Kuva m> n, itsinda rishya rya kode irashobora kuba Hariho 2 ^ m guhuza, bityo haribindi byinshi (2 ^ m-2 ^ n). Muri 2 ″ guhuza, itsinda ryiza rya kode ryatoranijwe muburyo bumwe nkitsinda ryemewe ryemewe, naho ibindi bikoreshwa nkitsinda ryabuzanyijwe kugirango babone imikorere myiza ya code. Kurugero, muri code ya 4B5B, code ya 5-bit ikoreshwa aho gukoresha 4-bit. Kode, kubitsinda 4-bit, hariho 2 ^ 4 = 16 gusa hamwe, naho kuri 5-biti, hariho 2 ^ 5 = 32 bitandukanye. Kugirango tugere kuri syncronisation, ntidushobora gukurikira bitarenze imwe iyobora "0 ″ hamwe ninyongera ebyiri" 0 ″ zikoreshwa muguhitamo amatsinda ya code, ahasigaye ni matsinda ya code ya disiki. Muri ubu buryo, niba itsinda rya code ryamugaye rigaragara kumpera yakira, bivuze ko hari ikosa mugikorwa cyo kohereza, bityo bikazamura ubushobozi bwo kumenya amakosa ya sisitemu. Kode zombi zibiri hamwe na code ya CMI birashobora gufatwa nka code ya 1B2B.
Muri sisitemu yo gutumanaho ya fibre optique, m = n + 1 iratoranywa, kandi 1B2B code, 2B3B code, 3B4B code na 5B6B. Muri byo, kode ya 5B6B yakoreshejwe muburyo nkumurongo wohereza umurongo kubitsinda rya gatatu nitsinda rya kane cyangwa byinshi.
Kode ya nBmB itanga syncronisation nziza nibikorwa byo gutahura amakosa, ariko kandi yishyura igiciro runaka, ni ukuvuga, umurongo wa ngombwa usabwa wiyongera ukurikije.
Igishushanyo mbonera cya code ya nBmT nuguhindura n binary code mumatsinda mashya ya kode ya m ternary code, na m
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