1) Koodu AMI
Aha zuru oke nke koodu AMI (Alternative Mark Inversion) bụ koodu ntụgharị akara ọzọ. oghere) nọgide na-agbanweghị agbanwe. Dịka:
Koodu ozi: 0 1 1 0 0 0 0 0 0 0 1 1 0 0 1 1…
Koodu AMI: 0 -1 +1 0 0 0 0 0 0 -1 +1 0 0 -1 +1…
Ụdị ebili mmiri kwekọrọ na koodu AMI bụ usoro pulse nwere ọkwa dị mma, adịghị mma na efu. Enwere ike were ya dị ka nrụrụ nke unipolar waveform, ya bụ, "0" ka kwekọrọ na ọkwa efu, ebe "1" kwekọrọ na ọkwa dị mma na nke na-adịghị mma ọzọ.
Uru nke koodu AMI bụ na ọ nweghị akụrụngwa DC, enwere obere ihe dị elu na nke dị ala, na ike na-etinye uche na ugboro nke 1/2 koodu ọsọ.
(Fig 6-4); Sekit codec dị mfe, enwere ike iji koodu polarity hụ ọnọdụ njehie; Ọ bụrụ na ọ bụ AMI-RZ waveform, enwere ike ịgbanwe ya ka ọ bụrụ unipolar ma ọ bụrụhaala na ebili mmiri zuru oke na-edozi ya mgbe ọ natara ya. RZ ebili mmiri nke enwere ike isi na ya wepụta ihe ngụ oge. N'ihi uru ndị a dị n'elu, koodu AMI aghọwo otu n'ime ụdị koodu nnyefe a na-ejikarị eme ihe.
Ọdịmma nke koodu AMI: Mgbe koodu izizi nwere ogologo usoro nke “0″, ọkwa nke mgbaama anaghị awụlikwa elu ogologo oge, nke na-eme ka o sie ike iwepu mgbama oge. Otu n'ime ụzọ dị irè isi dozie nsogbu nke ọbụna "0" koodu bụ iji HDB3 koodu.
(2) Koodu HDB3
Aha zuru oke nke koodu HDB3 bụ koodu bipolar nwere njupụta dị elu nke atọ. Ọ bụ ụdị koodu AMI emelitere. Ebumnuche nke mmelite ahụ bụ idowe uru nke koodu AMI wee merie adịghị ike ya ka ọnụ ọgụgụ nke "0" na-esote agaghị agafe atọ. Iwu itinye koodu ya bụ ndị a:
Buru ụzọ lelee ọnụọgụ nke “0″ na-esochi na koodu ozi. Mgbe ọnụọgụ "0" na-esochi erughị ma ọ bụ haha na 3, ọ bụ otu ihe ahụ na iwu ngbanwe nke koodu AMI. Mgbe ọnụ ọgụgụ nke “0″ na-eso ụzọ gafere 3, a ga-atụgharị nke ọ bụla n'ime “0″ nke anọ n'usoro ka ọ bụrụ ngalaba wee jiri “000V” dochie ya. V (uru +1 ma ọ bụ -1) kwesịrị inwe otu polarity dị ka ya ozugbo na-aga n'akụkụ na-abụghị "0" pulse (n'ihi na nke a na-agbaji polarity ọzọ iwu, ya mere V na-akpọ a na-ebibi usu). Oghere koodu V n'akụkụ ga-agbanwerịrị. Mgbe uru nke koodu V nwere ike iru ihe achọrọ na (2) mana enweghị ike iru ihe a chọrọ, wee dochie “0000″ na “B00V”. Uru nke B na-adaba na pulse V na-esonụ iji dozie nsogbu a. Ya mere, B ka a na-akpọ pulse modulation. A ga-agbanwekwa polarity nke nọmba nnyefe mgbe koodu V gachara.
Na mgbakwunye na uru nke koodu AMI, koodu HDB3 na-amachikwa ọnụ ọgụgụ nke koodu “0″ na-esoghị n'ihe na-erughị 3, nke mere na ewepụtara ozi oge n'oge nnabata. Ya mere, koodu HDB3 bụ ụdị koodu a na-ejikarị eme ihe na obodo m na Europe, na ụdị koodu interface dị n'okpuru otu A-law PCM quaternary bụ koodu HDB3 niile.
N'ime koodu AMI nke a kpọtụrụ aha n'elu na koodu HDB3, a na-atụgharị koodu ọnụọgụ abụọ ọ bụla ka ọ bụrụ koodu nwere uru 1-bit atọ (+1, 0, -1), ya mere a na-akpọkwa ụdị koodu a koodu 1B1T. Na mgbakwunye, ọ ga-ekwe omume ịmepụta koodu HDBn nke ọnụọgụ "0" anaghị agafe n.
(3) Koodu Biphase
A na-akpọkwa koodu Biphase dị ka koodu Manchester. Ọ na-eji oge ebili mmiri dị mma na nke na-adịghị mma iji nọchite anya “0″ na ntụgharị ihu ya ka ọ nọchite anya “1″. Otu n'ime iwu ngbanwe bụ na koodu "0" bụ koodu ọnụọgụ abụọ na-anọchi anya "01", na koodu "1" na-anọchi anya koodu ọnụọgụ abụọ "10". Ọmụmaatụ,
Koodu ozi: 1 1 0 0 1 0 1
Koodu nzipu ozi: 10 10 01 01 10 01 10
Usoro ebili mmiri biphasic bụ ụdị ebili mmiri NRZ bipolar nwere naanị ọkwa abụọ nke polarity na-emegide ya. Ọ nwere mwụli elu n'etiti etiti akara akara ọ bụla, yabụ na ọ nwere ozi oge bara ụba. Enweghị akụrụngwa DC, yana usoro ntinye koodu dịkwa mfe. Mwepu bụ na bandwit ejiri okpukpu abụọ na-ebelata, nke na-ebelata ọnụego ojiji nke bandwit ugboro ugboro. Koodu bi-phase dị mma maka izipu akụrụngwa ọdụ data n'ebe dị anya, a na-ejikarị ya dị ka ụdị koodu nnyefe na netwọk mpaghara.
(4) Koodu dị iche iche nke abụọ
Iji dozie mperi ndozi ihe kpatara ngbanwe polarity nke koodu bi-phase, enwere ike iji echiche nke koodu dị iche. Koodu biphase na-eji ngbanwe larịị n'etiti oge akara ọ bụla maka mmekọrịta yana akara ngosi koodu (ngbanwe site na adịghị mma gaa nke ọma na-anọchi anya ọnụọgụ abụọ “0″, na ngbanwe site na nke ọma gaa na-adịghị mma na-anọchi anya ọnụọgụ abụọ “1″). N'ime koodu koodu biphase dị iche, a na-eji mgbanwe ọkwa dị n'etiti akara ọ bụla maka ịmekọrịta, yana ma enwere mgbanwe ọzọ na mmalite nke akara ọ bụla, a na-eji iji chọpụta koodu mgbama. Ọ bụrụ na enwere mgbanwe, ọ pụtara ọnụọgụ abụọ “1″, ma ọ bụrụ na enweghị mgbanwe, ọ pụtara ọnụọgụ abụọ “0″. A na-ejikarị koodu a na netwọk mpaghara.
Koodu CMI
Koodu CMI bụ mbiri nke “koodu ngbanwe akara. Dịka koodu bi-phase, ọ bụkwa koodu ọkwa abụọ bipolar. Iwu nzuzo bụ: “1″ koodu na-anọchi anya ọzọ site na “11″ na “00″ koodu ọnụọgụ abụọ; A na-anọchi anya koodu “0″ ahụ nke ọma site na “01″, na ụdị ebili mmiri ya ka egosiri na eserese 6-5(c).
Koodu CMI dị mfe iji mejuputa ma nwee ozi oge bara ụba. Na mgbakwunye, ebe 10 bụ otu koodu amachibidoro, a gaghị enwe koodu atọ na-esochi, a pụkwara iji iwu a mee ihe maka nchọpụta njehie macroscopic. ITU-T akwadoro koodu a dị ka ụdị koodu interface nke PCM quartet na mgbe ụfọdụ a na-eji ya na sistemụ nnyefe ngwa anya yana ọnụego dị ala karịa 8.448Mb/s.
Mgbochi nzuzo
Iji kwalite arụmọrụ koodu ntinye ahịrị, a chọrọ ụdị nrụgharị ụfọdụ iji hụ na mmekọrịta ụkpụrụ na nchọpụta njehie. Iwebata koodu nzuzo nwere ike mezuo ebumnuche abụọ a ruo n'ókè ụfọdụ. Ụdị nzuzo nzuzo bụ koodu nBmB, koodu nBmT na ndị ọzọ.
koodu nBmB bụ ụdị ngọngọ koodu, nke na-ekewa n-bit ọnụọgụ abụọ nke ozi izizi n'ime otu wee dochie ya na koodu ọhụrụ m-bit binary code, ebe m>n. Kemgbe m>n, otu koodu ọhụrụ nwere ike ịbụ Enwere njikọ 2^m, yabụ enwere nchikota (2^m-2^n). N'ime nchikota 2″, a na-ahọrọ otu koodu dị mma n'ụzọ ụfọdụ dị ka otu koodu ekwenyere, ma ndị ọzọ ka ejiri ya dị ka otu koodu amachibidoro iji nweta arụmọrụ nzuzo dị mma. Dịka ọmụmaatụ, na koodu 4B5B, a na-eji koodu 5-bit kama koodu 4-bit. Nkwekọrịta, maka nchịkọta 4-bit, e nwere naanị 2^4=16 nchikota dị iche iche, na maka nchịkọta 5-bit, e nwere 2^ 5 = 32 dị iche iche. Iji nweta mmekọrịta, anyị enweghị ike ịgbaso ihe karịrị otu na-eduga “0″ na suffixes abụọ “0″ iji họrọ otu koodu, ndị ọzọ bụkwa otu koodu nwere nkwarụ. N'ụzọ dị otú a, ọ bụrụ na otu koodu nkwarụ na-apụta na njedebe nnata, ọ pụtara na e nwere njehie na usoro nnyefe, si otú ahụ na-emeziwanye ikike nchọpụta njehie nke usoro ahụ. Enwere ike iwere koodu abụọ abụọ na koodu CMI dị ka koodu 1B2B.
N'ime sistemụ nkwurịta okwu fiber optic, a na-ahọrọkarị m = n+1, yana koodu 1B2B, koodu 2B3B, koodu 3B4B na koodu 5B6B. N'ime ha, ejirila ụkpụrụ koodu 5B6B mee ihe dị ka ụkpụrụ nnyefe ahịrị maka otu nke atọ na nke anọ ma ọ bụ karịa.
Koodu nBmB na-enye ezigbo mmekọrịta na ọrụ nchọpụta njehie, mana ọ na-akwụkwa ụgwọ ụfọdụ, ya bụ, bandwit achọrọ na-abawanye n'otu aka ahụ.
Echiche imewe nke koodu nBmT bụ ịgbanwe koodu ọnụọgụ abụọ n'ime koodu koodu ọhụrụ nke m ternary codes, na m
Ihe dị n'elu bụ nkọwa nke isi ihe ọmụma nke "Ụdị Ụdị Ụdị Ụdị maka Baseband Transmission" nke Shenzhen Hi-Diwei Optoelectronics Technology Co., Ltd wetara gị, enwere m olileanya na isiokwu a nwere ike inyere gị aka ịbawanye ihe ọmụma gị. E wezụga nke a isiokwu ma ọ bụrụ na ị na-achọ ezigbo ngwa anya eriri nkwurịta okwu akụrụngwa emeputa ụlọ ọrụ ị nwere ike tụleegbasara anyị.
Shenzhen HDV photoelectric Technology Co., Ltd bụ tumadi a emeputa nke nkwurịta okwu ngwaahịa. Ka ọ dị ugbu a, akụrụngwa a na-emepụta na-ekpuchiUsoro ONU, ngwa anya modul usoro, Usoro OLT, nausoro transceiver. Anyị nwere ike ịnye ọrụ ahaziri maka ọnọdụ dị iche iche. A na-anabata gịndụmọdụ.
