1) AMI kodi
Dzina lonse la khodi ya AMI (Alternative Mark Inversion) ndi nambala ina yosinthira chizindikiro. blank) kukhalabe osasintha. Mwachitsanzo:
Nambala ya uthenga: 0 1 1 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 -1 +1 0 0 -1 +1 ...
Mawonekedwe ofananira ndi nambala ya AMI ndikutsatizana kwa pulse yokhala ndi milingo yabwino, yoyipa, ndi ziro. Itha kuwonedwa ngati kusinthika kwa mawonekedwe a unipolar waveform, ndiye kuti, "0" imagwirizanabe ndi zero, pomwe "1" imafanana ndi milingo yabwino komanso yoyipa mosinthana.
Ubwino wa AMI code ndikuti palibe gawo la DC, pali zigawo zingapo zapamwamba komanso zotsika kwambiri, ndipo mphamvu imayikidwa pafupipafupi pa liwiro la 1/2 code.
(Mkuyu 6-4); Dera la codec ndilosavuta, ndipo polarity ya code ingagwiritsidwe ntchito kuyang'ana zolakwika; ngati ndi mawonekedwe a mawonekedwe a AMI-RZ, amatha kusinthidwa kukhala unipolar bola atakonzedwanso atalandira. RZ waveform momwe magawo anthawi pang'ono amatha kuchotsedwa. Chifukwa cha zabwino zomwe zili pamwambazi, nambala ya AMI yakhala imodzi mwamitundu yomwe imagwiritsidwa ntchito kwambiri.
Kuipa kwa kachidindo ka AMI: Pamene code yoyambirira ili ndi mndandanda wautali wa "0", mlingo wa chizindikiro sudumpha kwa nthawi yaitali, zomwe zimapangitsa kuti zikhale zovuta kuchotsa chizindikiro cha nthawi. Imodzi mwa njira zothandiza kuthetsa vuto ngakhale "0" code ndi kugwiritsa HDB3 code.
(2) HDB3 kodi
Dzina lonse la code ya HDB3 ndi nambala yachitatu ya high-density bipolar code. Ndi mtundu wowongoleredwa wa AMI code. Cholinga cha kusinthaku ndikusunga ubwino wa AMI code ndikugonjetsa zofooka zake kuti chiwerengero cha "0" chotsatizana chisapitirire atatu. Malamulo ake a encoding ndi awa:
Choyamba onani nambala ya "0" motsatizana mu code code. Pamene chiwerengero cha "0" motsatizana ndi chocheperapo kapena chofanana ndi 3, chimakhala chofanana ndi lamulo la kabisidwe la AMI code. Chiwerengero cha "0" motsatizana chikadutsa 3, iliyonse mwa 4 motsatizana "0" idzasinthidwa kukhala gawo ndikusinthidwa ndi "000V". V (mtengo +1 kapena -1) uyenera kukhala ndi polarity yofanana ndi yomwe imayambira pafupi ndi "0" (chifukwa izi zimaphwanya lamulo la kusintha kwa polarity, kotero V amatchedwa kugunda kowononga). Pafupi V-code polarities iyenera kusinthana. Pamene mtengo wa V code ukhoza kukwaniritsa zofunikira mu (2) koma sungathe kukwaniritsa zofunikirazi, sinthani "0000" ndi "B00V". Mtengo wa B umagwirizana ndi V pulse yotsatirayi kuti athetse vutoli. Choncho, B amatchedwa modulation pulse. Polarity ya nambala yotumizira pambuyo pa V code iyeneranso kusinthidwa.
Kuphatikiza pazabwino za kachidindo ka AMI, kachidindo ka HDB3 kumachepetsanso kuchuluka kwa ma code "0" motsatizana mpaka kuchepera 3, kuti kutulutsa kwanthawi yayitali kukhale kotsimikizika panthawi yolandira. Chifukwa chake, kachidindo ka HDB3 ndiye mtundu womwe umagwiritsidwa ntchito kwambiri m'dziko langa ndi ku Europe, ndipo mitundu yamakodi yolumikizira pansipa A-law PCM quaternary group ndi ma code a HDB3.
Mu kachidindo ka AMI kotchulidwa pamwambapa ndi kachidindo ka HDB3, kachidindo kalikonse ka binary amasinthidwa kukhala kachidindo ka 1-bit kamtengo katatu (+1, 0, -1), kotero mtundu uwu wa code umatchedwanso 1B1T code. Kuphatikiza apo, ndizothekanso kupanga kachidindo ka HDBn komwe kuchuluka kwa "0" sikudutsa n.
(3) Biphase code
Khodi ya Biphase imatchedwanso kuti Manchester code. Imagwiritsa ntchito nthawi ya mafunde owoneka bwino komanso oyipa kuti ayimire "0" ndi mawonekedwe ake osinthika kuyimira "1". Limodzi mwa malamulo a kabisidwe ndi lakuti "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 1 0 1
Biphase kodi: 10 10 01 01 10 01 10
Biphasic code waveform ndi bipolar NRZ waveform yokhala ndi magawo awiri okha otsutsana. Ili ndi makwerero odumpha pakatikati pa chizindikiro chilichonse, kotero imakhala ndi zambiri zanthawi yayitali. Palibe gawo la DC, ndipo njira yolembera ndiyosavuta. Choyipa ndichakuti bandwidth yomwe imakhalapo imawirikiza kawiri, zomwe zimachepetsa kuchuluka kwa ma frequency band. Khodi ya bi-phase ndi yabwino kutumiza zida za data patali pang'ono, ndipo nthawi zambiri imagwiritsidwa ntchito ngati mtundu wa code yotumizira mu netiweki yapafupi.
(4) Bi-phase different code code
Pofuna kuthetsa vuto la decoding chifukwa cha kusintha kwa polarity kwa bi-phase code, lingaliro la kusiyana kwa code lingagwiritsidwe ntchito. Khodi ya Biphase imagwiritsa ntchito kusintha kwapakati pa nthawi ya chizindikiro chilichonse cholumikizira ndikuyimira chizindikiro (kusintha kuchokera ku zoyipa kupita ku zabwino kumayimira binary "0", ndipo kusintha kuchokera ku zabwino kupita ku zoyipa kumayimira "1″". M'mitundu yosiyana ya biphase code code, kusintha kwapakati pakati pa chizindikiro chilichonse kumagwiritsidwa ntchito pogwirizanitsa, ndipo ngati pali kusintha kowonjezera kumayambiriro kwa chizindikiro chilichonse kumagwiritsidwa ntchito kuti mudziwe chizindikiro cha chizindikiro. Ngati pali kusintha, kumatanthauza "1", ndipo ngati palibe kusintha, kumatanthauza binary "0". Khodi iyi imagwiritsidwa ntchito nthawi zambiri pamanetiweki amderali.
CMI kodi
Khodi ya CMI ndi chidule cha "mark inversion code. Monga bi-phase code, ilinso ndi bipolar two-level code. Lamulo la zolemba ndi: "1" code imayimiridwa mosinthana ndi "11" ndi "00" code ya manambala awiri; "0" code ikuimiridwa ndi "01", ndipo mawonekedwe ake akuwonetsedwa pa Chithunzi 6-5 (c).
Zizindikiro za CMI ndizosavuta kugwiritsa ntchito ndipo zimakhala ndi zambiri zamanthawi. Kuphatikiza apo, popeza 10 ndi gulu loletsedwa, sipadzakhalanso ma code atatu otsatizana, ndipo lamuloli lingagwiritsidwe ntchito pozindikira zolakwika za macroscopic. Khodi iyi yalimbikitsidwa ndi ITU-T monga mtundu wa mawonekedwe amtundu wa PCM quartet ndipo nthawi zina amagwiritsidwa ntchito mu makina opangira chingwe chodutsa ndi mlingo wotsika kuposa 8.448Mb / s.
Tsekani kabisidwe
Kuti muwongolere magwiridwe antchito a mizere, mtundu wina wa redundancy umafunika kuwonetsetsa kulumikizana kwapateni ndikuzindikira zolakwika. Kuyamba kwa block coding kumatha kukwaniritsa zolinga zonsezi pamlingo wina. Mtundu wa block coding ndi nBmB code, nBmT code ndi zina zotero.
nBmB code ndi mtundu wa block code code, yomwe imagawaniza n-bit binary code ya chidziwitso choyambirira kukhala gulu ndikulowa m'malo mwake ndi gulu latsopano la code ya m-bit binary, pomwe m>n. Popeza m>n, gulu latsopano la code likhoza kukhala Pali 2^m kuphatikiza, kotero pali zambiri (2^m-2^n) kuphatikiza. Pakati pa 2 "zophatikizira, gulu labwino la ma code limasankhidwa mwanjira ina ngati gulu lololedwa, ndipo ena onse amagwiritsidwa ntchito ngati gulu loletsedwa kuti apeze ma codec abwino. Mwachitsanzo, mu 4B5B coding, 5-bit code imagwiritsidwa ntchito m'malo mwa 4-bit code. Coding, pagulu la 4-bit, pali 2^4=16 zophatikizira zosiyana zokha, ndipo pamagulu a 5-bit, pali 2^5=32 zophatikizira zosiyanasiyana. Kuti tikwaniritse kulunzanitsa, sitingatsatire osapitilira "0" ndi ma suffixes awiri "0" amagwiritsidwa ntchito posankha magulu a ma code, ndipo ena onse ndi magulu olemala. Mwanjira iyi, ngati gulu lolemala limawonekera pamapeto olandila, zikutanthauza kuti pali cholakwika pakupatsirana, potero kuwongolera kuthekera kozindikira zolakwika zadongosolo. Ma code a bi-phase ndi CMI amatha kuonedwa 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, ndondomeko ya 5B6B yakhala ikugwiritsidwa ntchito ngati njira yotumizira mzere wa gulu lachitatu ndi gulu lachinayi kapena kuposerapo.
Khodi ya nBmB imapereka kulumikizana kwabwino ndi ntchito zozindikira zolakwika, koma imaperekanso mtengo wina, ndiko kuti, bandwidth yofunikira ikuwonjezeka molingana.
Lingaliro la kapangidwe ka code ya nBmT ndikusintha n ma code binary kukhala gulu latsopano la ma code a m ternary, ndi m.
Zomwe zili pamwambazi ndizofotokozera mfundo za "Common Code Types for Baseband Transmission" zomwe zabweretsedwa kwa inu ndi Shenzhen Hi-Diwei Optoelectronics Technology Co., Ltd., ndikuyembekeza kuti nkhaniyi ingakuthandizeni kuonjezera chidziwitso chanu. Kupatula nkhaniyi ngati mukuyang'ana kampani yabwino yopanga zida zoyankhulirana zama fiber zomwe mungaganizirezambiri zaife.
Shenzhen HDV photoelectric Technology Co., Ltd. ndiyomwe imapanga zinthu zolumikizirana. Pakadali pano, zida zomwe zimapangidwa zimakwiriraZithunzi za ONU, Optical module mndandanda, Zithunzi za OLT,nditransceiver mndandanda. Titha kupereka ntchito makonda pazochitika zosiyanasiyana. Mwalandiridwafunsani.
