1) Iyo AMI kodhi
Iro zita rizere rekodhi ye AMI (Alternative Mark Inversion) ndiyo imwe kodhi inversion kodhi. blank) inoramba isina kuchinjwa. Eg:
Kodhi yemeseji: 0 1 1 0 0 0 0 0 0 0 1 1 0 0 1 1…
AMI kodhi: 0 -1 +1 0 0 0 0 0 0 0 0 -1 +1 0 0 -1 +1 ...
Iyo waveform inoenderana neiyo AMI kodhi ndeye pulse sequence ine yakanaka, yakaipa, uye zero mazinga. Inogona kutariswa seshanduko yeunipolar waveform, kureva kuti, "0" ichiri kuenderana ne zero level, nepo "1" inoenderana neakanaka uye akashata nhanho.
Kubatsira kwe AMI kodhi ndeyekuti hapana chikamu cheDC, pane mashoma epamusoro uye akaderera-frequency zvikamu, uye simba rinoiswa pane frequency ye1/2 kodhi kasidhi.
(Mufananidzo 6-4); Iyo codec yedunhu iri nyore, uye iyo kodhi polarity inogona kushandiswa kutarisa kukanganisa mamiriro; kana iri AMI-RZ waveform, inogona kuchinjwa kuita unipolar chero izere-wave yakagadziridzwa mushure mekugamuchira. RZ waveform kubva mairi zvishoma zvimiro zvenguva zvinogona kubviswa. Nekuda kwemabhenefiti ari pamusoro, iyo AMI kodhi yave imwe yeanonyanya kushandiswa ekufambisa kodhi mhando.
Kuipa kweiyo AMI kodhi: Kana iyo yekutanga kodhi ine refu yakatevedzana ye "0", mwero wechiratidzo hausvetuke kwenguva yakareba, izvo zvinoita kuti zviome kubvisa chiratidzo chenguva. Imwe yenzira dzinoshanda dzekugadzirisa dambudziko re "0" kodhi kushandisa HDB3 kodhi.
(2) Iyo HDB3 kodhi
Zita rizere reHDB3 kodhi ndiyo yechitatu-odha yepamusoro-density bipolar kodhi. Iyo imhando yakagadziridzwa yeAMI kodhi. Chinangwa chekuvandudza ndechekuchengetedza zvakanakira iyo AMI kodhi uye kukunda zvikanganiso zvayo kuitira kuti nhamba yeakateedzana "0" s isapfuure matatu. Mitemo yayo yekukodha ndeyotevera:
Chekutanga tarisa nhamba yeakatevedzana "0"s mune meseji kodhi. Kana iyo nhamba inoteedzana "0"s iri pasi kana kuenzana ne3, yakafanana neiyo encoding mutemo weiyo AMI kodhi. Kana nhamba ye "0" inotevedzana ikadarika 3, imwe neimwe ye4 inoteedzana "0" inoshandurwa kuita chikamu uye ichitsiviwa ne"000V". V (kukosha +1 kana -1) inofanira kunge iine polarity yakafanana neinotangira padyo isiri-”0″ pulse (nekuti izvi zvinotyora mutemo wepolarnation alternation, saka V inodaidzwa kuti pulse inoparadza). Pedyo neV-code polarities inofanira kuchinjana. Kana kukosha kweV kodhi kuchikwanisa kuzadzisa zvinodiwa mu (2) asi isingakwanise kuita izvi, chinja "0000" ne "B00V". Kukosha kweB kunoenderana neinotevera V pulse kugadzirisa dambudziko iri. Nokudaro, B inonzi modulation pulse. Iyo polarity yenhamba yekutumira mushure meiyo V kodhi inofanirawo kuchinjwa.
Pamusoro pezvakanakira iyo AMI kodhi, iyo HDB3 kodhi zvakare inodzika nhamba yeanoteedzana "0" makodhi kusvika pasi pe3, kuitira kuti kubviswa kweruzivo rwenguva kugone kuvimbiswa panguva yekugamuchira. Naizvozvo, iyo HDB3 kodhi ndiyo inonyanya kushandiswa kodhi mhando munyika yangu neEurope, uye iyo interface kodhi mhando pazasi A-mutemo PCM quaternary boka ese HDB3 macode.
Mune iyo AMI kodhi yataurwa pamusoro uye HDB3 kodhi, yega bhinari kodhi inoshandurwa kuita kodhi ine 1-bit matatu-nhanho kukosha (+1, 0, -1), saka iyi mhando yekodhi inonzi zvakare 1B1T kodhi. Pamusoro pezvo, zvinogonekawo kugadzira kodhi yeHDBn umo nhamba ye “0″s isingapfuure n.
(3) Biphase code
Iyo Biphase kodhi inonziwo Manchester kodhi. Inoshandisa nguva yakanaka uye yakaipa symmetrical square waves kumiririra "0" uye inverse waveform kumiririra "1". Imwe yemitemo yekukodha ndeyekuti "0" kodhi inomiririrwa ne"01" kodhi ine manhamba maviri, uye "1" kodhi inomiririrwa ne "10" kodhi ine manhamba maviri. Semuyenzaniso,
Kodhi yemeseji: 1 1 0 0 1 0 1
Biphase code: 10 10 01 01 10 01 10
Iyo biphasic kodhi waveform ndeye bipolar NRZ waveform ine maviri chete mazinga akatarisana polarity. Iyo ine nhanho yekusvetuka panzvimbo yepakati pechiratidzo chega chega, saka ine ruzivo rwakapfuma rwenguva. Iko hakuna DC chikamu, uye iyo encoding process zvakare iri nyore. Izvo zvisingabatsiri ndezvokuti bhanwidth yakagarwa yakapetwa kaviri, iyo inoderedza kushandiswa kwehuwandu hwebhendi. Iyo bi-phase kodhi yakanakira kutumira data terminal michina pamusoro pemafanha mapfupi, uye inowanzoshandiswa semhando yekodhi yekutumira mune yemunharaunda nharaunda network.
(4) Bi-phase differential code
Kuti ugadzirise chikanganiso chedecoding chakakonzerwa nekudzoserwa kwepolar kwebi-phase kodhi, iyo pfungwa yekusiyanisa kodhi inogona kushandiswa. Biphase kodhi inoshandisa danho rekuchinja pakati penguva yechiratidzo chega chega chekubatanidza uye chiratidzo chechiratidzo chekumiririra (shanduko kubva kune yakaipa kuenda kune yakanaka inomiririra bhinari "0", uye shanduko kubva kune yakanaka kuenda kune yakaipa inomiririra bhinary "1″). Mukusiyanisa biphase kodhi coding, nhanho yekuchinja pakati pechiratidzo chega chega inoshandiswa kuwiriranisa, uye kana paine imwe shanduko pakutanga kwechiratidzo chega chega inoshandiswa kuona kodhi yechiratidzo. Kana paine shanduko, zvinoreva bhinari "1", uye kana pasina shanduko, zvinoreva bhinary "0". Iyi kodhi inowanzo shandiswa mumambure emunharaunda.
CMI kodhi
CMI kodhi ndiyo chidimbu che "mark inversion kodhi. Kufanana neiyo bi-phase kodhi, iri zvakare bipolar maviri-level kodhi. Mutemo wekukodha ndewekuti: "1" kodhi inomiririrwa neimwe "11" uye "00" kodhi ine manhamba maviri; iyo "0" kodhi inomiririrwa ne"01", uye waveform yayo inoratidzwa mumufananidzo 6-5(c).
CMI makodhi ari nyore kushandisa uye ane ruzivo rwakapfuma rwenguva. Mukuwedzera, sezvo 10 iboka rekodhi rakarambidzwa, hapazovi nemakodhi matatu akateedzana, uye mutemo uyu unogona kushandiswa pakuona kukanganisa kwema macroscopic. Iyi kodhi yakakurudzirwa neITU-T semhando yekodhi yekodhi yePCM quartet uye dzimwe nguva inoshandiswa mumagetsi ekufambisa tambo yemagetsi ine chiyero chakaderera kupfuura 8.448Mb / s.
Vhara encoding
Kuti uvandudze mutsara wekukodha kuita, imwe mhando yekudzokororwa inodiwa kuti ive nechokwadi chekuwiriranisa patani uye nekuonekwa kwekukanganisa. Kuunzwa kweblock coding kunogona kuzadzisa zvese izvi zvinangwa kusvika pamwero wakati. Iyo fomu ye block coding ndeye nBmB kodhi, nBmT kodhi uye zvichingodaro.
nBmB kodhi imhando yeblock coding, inokamura n-bit binary kodhi yerukova rwekutanga ruzivo muboka uye inoitsiva neboka idzva rekodhi rem-bit binary kodhi, uko m> n. Kubva m>n, boka rekodhi idzva rinogona kunge Kuine 2^m misanganiswa, saka kune akawanda (2^m-2^n) misanganiswa. Pakati peiyo 2 ″ musanganiswa, iyo yakanaka kodhi boka rinosarudzwa neimwe nzira seyakatenderwa kodhi boka, uye mamwe anoshandiswa seakarambidzwa kodhi boka kuti uwane yakanaka coding performance. Semuenzaniso, mu4B5B coding, iyo 5-bit kodhi inoshandiswa pachinzvimbo che4-bit kodhi. Coding, ye 4-bit grouping, pane chete 2^4=16 misanganiswa yakasiyana, uye pa5-bit grouping, pane 2^5=32 misanganiswa yakasiyana. Kuti tiwane kuwiriranisa, isu hatigone kutevedzera zvinopfuura imwechete inotungamira "0" uye Maviri ma suffixes "0" anoshandiswa kusarudza mapoka emakodhi, uye mamwe akaremara macode mapoka. Nenzira iyi, kana boka rekodhi rakaremara richionekwa pamagumo ekugamuchira, zvinoreva kuti pane chikanganiso muhutano hwekutumira, nokudaro nekuvandudza kukwanisa kwekuona kukanganisa kwegadziriro. Ose maviri bi-phase kodhi uye CMI makodhi anogona kutorwa se1B2B makodhi.
Mune optical fiber communication system, m = n + 1 inowanzosarudzwa, uye 1B2B code, 2B3B code, 3B4B code uye 5B6B code inotorwa. Pakati pavo, iyo 5B6B kodhi kodhi yave ichishandiswa senzira yekufambisa kodhi kodhi yeboka rechitatu neboka rechina kana kupfuura.
Iyo nBmB kodhi inopa yakanaka kuwiriranisa uye kukanganisa kwekuona mabasa, asi inobhadharawo imwe mutengo, ndiko kuti, inodiwa bandwidth inowedzera zvinoenderana.
Pfungwa yekugadzira yenBmT kodhi ndeyekushandura n mabhinari makodhi kuita boka idzva rekodhi rem ternary codes, uye m.
Izvo zviri pamusoro apa tsananguro yezvizivo zve "Common Code Types for Baseband Transmission" yakaunzwa kwauri neShenzhen Hi-Diwei Optoelectronics Technology Co., Ltd., Ndinovimba chinyorwa ichi chinogona kukubatsira kuti uwedzere ruzivo rwako. Kunze kwechinyorwa ichi kana iwe uchitsvaga yakanaka optical fiber yekutaurirana michina yekugadzira kambani yaungafunganezvedu.
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