(1) AMI kodi
Khodi ya AMI(Alternative Mark Inversion) ndi dzina lathunthu la code inversion code, lamulo lake la kabisidwe ndikusintha mosinthana ma code code "1" (chizindikiro) kukhala "+1" ndi "-1", pomwe "0" ( chopanda kanthu) sichinasinthe. Mwachitsanzo:
Nambala ya uthenga: 0 1 1 0 0 0 0 0 0 0 0 1 1 0 0 1 1
AMI kodi: 0-1 +1 0 0 0 0 0 0 0 0 0 0 0 1 +1 0 0 0 0 1 +1
Mawonekedwe ofananira ndi AMI code ndi masitima apamtunda omwe ali ndi milingo yabwino, yoyipa komanso zero. Itha kuwonedwa ngati mawonekedwe a unipolar waveform, ndiye kuti, "0" imagwirizanabe ndi milingo ya ziro, ndipo "1" imafanana ndi milingo yabwino komanso yoyipa.
Ubwino wa AMI code ndikuti palibe gawo la DC, ndipo magawo apamwamba ndi otsika pafupipafupi ndi ang'onoang'ono, ndipo mphamvu imayikidwa pafupipafupi pa liwiro la 1/2 yadi.
(Chithunzi 6-4); Dongosolo la codec ndi losavuta, ndipo cholakwika cha code chikhoza kuwonedwa pogwiritsa ntchito lamulo la kusinthana kwa polarity. Ngati ndi mawonekedwe a mawonekedwe a AMI-RZ, atalandira, malinga ngati kukonzanso kwathunthu kwa mafunde, kungasinthidwe kukhala mawonekedwe a unipolar RZ waveform, momwe gawo la nthawi likhoza kuchotsedwa. Poganizira zaubwino womwe uli pamwambapa, nambala ya AMI yakhala imodzi mwama code omwe amagwiritsidwa ntchito kwambiri.
Kuipa kwa kachidindo ka AMI: Khodi yoyambirira ikakhala ndi "0" chingwe chachitali, mulingo wa siginecha sudumpha kwa nthawi yayitali, zomwe zimapangitsa kuti pakhale vuto lotulutsa chizindikiro chanthawi. Imodzi mwa njira zothandiza zothetsera vuto la "0" code ndi kugwiritsa ntchito HDB3 code.
(2) HDB3 kodi
Dzina lonse la code ya HDB3 ndi nambala yachitatu yapamwamba kwambiri ya bipolar. Ndi mtundu wowongoleredwa wa kachidindo ka AMI, cholinga chowongolera ndikusunga zabwino za AMI code ndikuthana ndi zofooka zake, kuti chiwerengero cha "0" chisapitirire atatu. Malamulo ake a encoding ndi awa:
Yang'anani chiwerengero cha ziro cholumikizidwa ku nambala ya uthenga. Pamene chiwerengero cha "0" ndi chocheperapo kapena chofanana ndi 3, lamulo lolembera ndilofanana ndi la AMI code. Chiwerengero cha ziro zotsatizana chikaposa atatu, ziro zilizonse zotsatizana zimasinthidwa kukhala kagawo kakang'ono ndikusinthidwa ndi 000V. V (kutengera mtengo +1 kapena -1) kuyenera kukhala ndi polarity yofanana ndi yomwe inali pafupi ndi "0" pulse (chifukwa ichi chimaphwanya lamulo la kusintha kwa polarity, V amatchedwa kugunda kwachiwonongeko). Pafupi V-code polarities iyenera kusinthana. Pamene mtengo wa V code ukhoza kukwaniritsa zofunikira mu (2) koma sungathe kukwaniritsa zofunikirazi, "0000" imasinthidwa ndi "B00V". Mtengo wa B ndi wofanana ndi V pulse yotsatirayi kuti athetse vutoli. Chifukwa chake, B amatchedwa kugunda kowongolera. Polarity ya kufalitsa manambala pambuyo pa V code iyeneranso kusinthana.
Kuphatikiza pa zabwino za AMI code, HDB3 code imachepetsanso nambala ya "0" mpaka 3, kotero kuti zambiri zanthawi zitha kuchotsedwa mukalandira. Chifukwa chake, HDB3 code ndiyo yomwe imagwiritsidwa ntchito kwambiri ku China ndi Europe ndi mayiko ena, ndipo mawonekedwe amtundu wamalamulo A PCM pansipa magulu anayi ndi HDB3 code.
Mu kachidindo kapamwamba ka AMI ndi kachidindo ka HDB3, kachidindo kalikonse kachizindikiro kamasinthidwa kukhala kachidindo kamodzi ka katatu (+1, 0,-1), kotero mtundu uwu wa code umatchedwanso 1B1T code. Kuphatikiza apo, nambala ya HDBn imatha kupangidwa kuti nambala ya "0" isapitirire n.
(3) biphase kodi
Khodi ya Biphasic imadziwikanso kuti Manchester code. Imagwiritsa ntchito mafunde owoneka bwino komanso oyipa anthawi imodzi kuyimira "0" ndi mawonekedwe ake osinthika kuti aimirire "1". Limodzi mwa malamulo amakodi ndiloti "0" code imayimiridwa ndi "01" code ya manambala awiri, ndipo "1" code imayimiridwa ndi "10" code ya manambala awiri, mwachitsanzo:
Nambala ya uthenga: 1 1 0 0 0 1 0 1
Biphase kodi: 10 10 01 01 10 01 10
Bipolar code waveform ndi bipolar NRZ waveform yokhala ndi magawo awiri okha otsutsana. Ili ndi kulumpha kwapakati pakatikati pa chizindikiro chilichonse, chifukwa chake imakhala ndi chidziwitso chanthawi yayitali, ndipo palibe gawo la DC, ndipo njira yolembera ndiyosavuta. Choyipa ndichakuti bandwidth yomwe amakhala nayo imachulukitsidwa kawiri, kotero kuti ma frequency band amachepetsa. Khodi ya Biphase ndiyoyenera kutumizira zida zazifupi zazifupi, ndipo nthawi zambiri imagwiritsidwa ntchito ngati mtundu wapamtundu wapaintaneti.
(4) Zosiyana za biphase code
Pofuna kuthetsa zolakwika za decoding zomwe zimayambitsidwa ndi kusintha kwa polarity mu biphasic codes, lingaliro la ma code osiyana lingatengedwe. Zizindikiro za Biphasic zimalumikizidwa ndikuyimiridwa ndi kulumpha kwapakati pakati pa nthawi ya chizindikiro chilichonse (kudumpha kuchokera ku zoyipa kupita ku zabwino kumayimira "0" wa binary ndipo kulumpha kuchokera ku zabwino kupita ku zoyipa kumayimira "1". M'mitundu yosiyanasiyana ya biphase coding, kulumpha kwapakati pakati pa chinthu chilichonse kumagwiritsidwa ntchito polumikizana, ndipo ngati pali kulumpha kowonjezera kumayambiriro kwa chinthu chilichonse kumagwiritsidwa ntchito kudziwa chizindikiro. Ngati pali kulumpha, kumasonyeza "1", ndipo ngati palibe kulumpha, kumasonyeza "0" yachiphamaso. Khodi iyi imagwiritsidwa ntchito nthawi zambiri pamanetiweki amderali.
(5) CMI kodi
Khodi ya CMI ndi yachidule ya code reversal code, ndipo yofanana ndi bipolar code, ilinso ndi bipolar bipolar flat code. Malamulo ake amakhoti ndi: “1″ code imayimiridwa mosinthana ndi “11” ndi “00″ manambala awiri; Khodi ya 0 imayimiridwa ndi 01, ndipo mawonekedwe ake akuwonetsedwa mu Chithunzi 6-5 (c).
Khodi ya CMI ndiyosavuta kugwiritsa ntchito ndipo imakhala ndi zambiri zamanthawi. Kuphatikiza apo, popeza 10 ndi gulu lolemala, manambala opitilira atatu sangawonekere, ndipo lamuloli lingagwiritsidwe ntchito pozindikira zolakwika zazikulu. Khodi iyi yalimbikitsidwa ndi ITU-T ngati mtundu wa code code ya PCM quad-group, ndipo nthawi zina imagwiritsidwa ntchito pamakina otumizira ma chingwe okhala ndi mitengo yochepera 8.448Mb / s.
(6) Tsekani zolemba
Kuti muwongolere magwiridwe antchito a ma code code, mtundu wina wa redundancy umafunika kuwonetsetsa kuti kulunzanitsa ndi kuzindikira zolakwika za ma code. Kuyambitsa kwa block coding kumatha kukwaniritsa zolinga zonse ziwiri pamlingo wina. Mtundu wa block code uli ndi nBmB code, nBmT code ndi zina zotero.
NBmB code ndi mtundu wa code code, yomwe imagawa nambala ya binary ya n-bit ya chidziwitso choyambirira kukhala gulu, ndikusintha kukhala gulu latsopano la M-bit binary code, pomwe m> n. Chifukwa m>n, kachidindo katsopano kakhoza kukhala ndi 2^m kuphatikiza, kotero pali zambiri (2^m-2^n) kuphatikiza. Mu 2 "kuphatikiza, gulu labwino la ma code limasankhidwa ngati gulu lololedwa mwanjira ina, ndipo ena onse amagwiritsidwa ntchito ngati gulu lolumala kuti apeze ntchito yabwino yolembera. Mwachitsanzo, mu kabisidwe ka 4B5B, m'malo mwa 4-bit encoding ndi 5-bit encoding, pali 2^4=16 yokha yophatikizika yosiyana pamagulu a 4-bit, ndi 2^5=32 kuphatikiza kosiyanasiyana kwa 5- kupanga magulu pang'ono. Kuti tikwaniritse kulunzanitsa, titha kusankha magulu amitundu m'njira yosapitilira "0" yotsogola imodzi ndi ma suffixes awiri "0", ndipo ena onse ndi magulu olemala. Mwanjira iyi, ngati pali code yolemala yomwe imayikidwa pamapeto olandira, imasonyeza kuti pali cholakwika cha code mu njira yopatsirana, motero kuwongolera luso lozindikira zolakwika za dongosolo. Ma code a biphase ndi ma CMI omwe afotokozedwa kale amatha kuwonedwa ngati ma 1B2B.
Mu optical fiber communication system, m=n+1 nthawi zambiri amasankhidwa, ndipo 1B2B code, 2B3B code, 3B4B code ndi 5B6B code imatengedwa. Pakati pawo, code 5B6B yakhala ikugwiritsidwa ntchito ngati njira yotumizira mizere yamagulu a cubic ndi magulu oposa anayi.
Khodi ya nBmB imapereka kulumikizana kwabwino ndikuzindikira zolakwika, koma imabwera pamtengo, ndiko kuti, bandwidth yofunikira imawonjezeka.
Lingaliro la kapangidwe ka nambala ya nBmT ndikusinthira n ma code binary kukhala ma code m ternary, ndi m
Zomwe zili pamwambazi ndi Shenzhen HDV phoelectron Technology Ltd. kuti ikubweretsereni chidziwitso cha "baseband transmission common code type", ndikuyembekeza kukuthandizani, Shenzhen HDV phoelectron Technology Ltd.ONUmndandanda, ma transceiver angapo,OLTmndandanda, komanso kupanga gawo mndandanda, monga: Kulankhulana gawo kuwala, gawo kuwala kulankhulana, maukonde kuwala gawo, kulankhulana kuwala gawo, kuwala CHIKWANGWANI gawo, Efaneti kuwala CHIKWANGWANI gawo, etc., angapereke lolingana utumiki khalidwe zosowa osiyana owerenga '. , landirani kudzacheza kwanu.