1) ʻO ke code AMI
ʻO ka inoa piha o ke code AMI (Alternative Mark Inversion) ka code inversion mark ʻokoʻa. blank) noho ʻaʻole hoʻololi. E laʻa:
Ka helu memo: 0 1 1 0 0 0 0 0 0 0 0 1 1 0 0 1 1…
AMI code: 0 -1 +1 0 0 0 0 0 0 0 -1 +1 0 0 -1 +1…
ʻO ka nalu e pili ana i ke code AMI he kaʻina pulse me nā pae maikaʻi, maikaʻi ʻole, a me ka ʻole. Hiki ke no'ono'o 'ia he ho'ololi 'ana o ka nalu unipolar, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ho'i, 'o ia ka "0" i ka pae 'ole, 'oiai 'o "1\" e pili ana i nā pae maika'i a me nā pae 'ole.
ʻO ka pōmaikaʻi o ka code AMI ʻaʻohe mea DC, he liʻiliʻi nā ʻāpana kiʻekiʻe a me nā haʻahaʻa haʻahaʻa, a paʻa ka ikehu ma ke alapine o 1/2 code speed.
(Fig. 6-4); He maʻalahi ke kaʻapuni codec, a hiki ke hoʻohana i ka polarity code e nānā i ke kūlana hewa; inā he ʻano nalu AMI-RZ, hiki ke hoʻololi ʻia i unipolar i ka wā i hoʻoponopono ʻia ka nalu piha ma hope o ka loaʻa ʻana. ʻO ka nalu RZ kahi e hiki ai ke unuhi ʻia nā ʻāpana manawa bit. Ma muli o nā pono o luna, ua lilo ka code AMI i hoʻokahi o nā ʻano code hoʻouna maʻamau.
ʻO ka pōʻino o ka code AMI: Ke loaʻa i ka code kumu he moʻo lōʻihi o "0", ʻaʻole lele ka pae o ka hōʻailona no ka manawa lōʻihi, he mea paʻakikī ke unuhi i ka hōʻailona manawa. ʻO kekahi o nā ala kūpono e hoʻoponopono ai i ka pilikia o ke code "0" ʻo ia ka hoʻohana ʻana i ka code HDB3.
(2) ʻO ke code HDB3
ʻO ka inoa piha o ka code HDB3 ʻo ia ke kolu o ka helu bipolar kiʻekiʻe kiʻekiʻe. He ʻano hoʻomaikaʻi ʻia o ka code AMI. ʻO ke kumu o ka hoʻomaikaʻi ʻana, ʻo ia ka mālama ʻana i nā pono o ka code AMI a lanakila i kona mau hemahema i ʻole ka nui o nā "0″s i ʻoi aku ma mua o ʻekolu. ʻO kāna mau lula hoʻopāpā penei:
E nānā mua i ka helu o nā "0″s i ka helu memo. Ke emi a like paha ka helu o nā “0″s me 3, ua like ia me ka lula hoʻopāpā o ke code AMI. Ke ʻoi aku ka nui o nā “0″s i ka 3, e hoʻololi ʻia kēlā me kēia o nā “0″s 4 i ʻāpana a hoʻololi ʻia me “000V”. Pono ka V (waiwai +1 a i ʻole -1) i ka polarity like me kona puʻupuʻu pili ʻole-”0″ (no ka mea, ua haki kēia i ka lula hoʻololi polarity, no laila ua kapa ʻia ʻo V he pulse luku). Pono nā polarities V-code pili. Inā hiki i ka waiwai o ke code V ke kūpono i nā koi ma (2) akā ʻaʻole hiki ke hoʻokō i kēia koi, a laila e hoʻololi i ka "0000" me "B00V". Ua kūlike ka waiwai o B me ka V pulse e hoʻoholo i kēia pilikia. No laila, kapa ʻia ʻo B he pulse modulation. Pono e hoʻololi ʻia ka polarity o ka helu hoʻouna ma hope o ke code V.
Ma waho aʻe o nā pono o ka code AMI, ua kaupalena ka code HDB3 i ka helu o nā code "0" i lalo o 3, i hiki ke hōʻoia ʻia ka unuhi ʻana o ka ʻike manawa i ka wā o ka hoʻokipa. No laila, ʻo ka code HDB3 ka ʻano code code i hoʻohana nui ʻia ma koʻu ʻāina a me ʻEulopa, a ʻo nā ʻano code interface ma lalo o ka A-law PCM quaternary group he mau code HDB3 āpau.
Ma ka helu AMI a me ka code HDB3 i ʻōlelo ʻia ma luna, ua hoʻololi ʻia kēlā me kēia code binary i code me ka waiwai 1-bit ʻekolu pae (+1, 0, -1), no laila ua kapa ʻia kēia ʻano code he code 1B1T. Eia hou, hiki ke hoʻolālā i kahi code HDBn i ʻoi aku ka nui o ka "0″s ma mua o n.
(3) ʻO ke code Biphase
Ua kapa ʻia ka code Biphase ʻo Manchester code. Hoʻohana ia i ka manawa o nā hawewe huinahā like ʻole a maikaʻi ʻole e hōʻike i ka "0" a me kona ʻano nalu inverse e hōʻike i ka "1". ʻO kekahi o nā lula hoʻopāpā ʻo ia ka "0" code e hōʻike ʻia e kahi "01" helu helu ʻelua, a ʻo ka "1" code e hōʻike ʻia e ka "10" helu helu ʻelua. ʻo kahi laʻana,
Helu memo: 1 1 0 0 1 0 1
Ka helu helu ʻelua: 10 10 01 01 10 01 10
ʻO ka nalu helu biphasic he ʻano nalu NRZ bipolar me ʻelua wale nō pae o ka polarity kūʻē. Loaʻa iā ia nā lele kiʻekiʻe ma ke kikowaena o kēlā me kēia manawa hōʻailona, no laila, loaʻa iā ia ka ʻike kikoʻī o ka manawa. ʻAʻohe mea DC, a maʻalahi hoʻi ke kaʻina hana hoʻopili. ʻO ka hemahema ʻo ia ka pālua ʻana o ka bandwidth i noho ʻia, e hōʻemi ana i ka hoʻohana ʻana o ka band frequency. Maikaʻi ka code bi-phase no ka hoʻouna ʻana i nā lako kikowaena ʻikepili ma kahi mamao pōkole, a hoʻohana pinepine ʻia ʻo ia ke ʻano o ka code hoʻouna ma kahi pūnaewele wahi kūloko.
(4) Ka helu ʻokoʻa bi-phase
I mea e hoʻoponopono ai i ka hewa decoding ma muli o ka hoʻohuli polarity o ka code bi-phase, hiki ke hoʻohana ʻia ka manaʻo o ka code differential. Hoʻohana ka code Biphase i ka hoʻololi pae ma waena o ka lōʻihi o kēlā me kēia hōʻailona no ka hoʻonohonoho ʻana a me nā hōʻailona hōʻailona code (ʻo ka hoʻololi ʻana mai ka ʻino a i ka maikaʻi e hōʻike ana i ka binary “0″, a ʻo ka hoʻololi ʻana mai ka maikaʻi a i ka maikaʻi ʻole e hōʻike ana i ka binary “1″). I ka ʻokoʻa biphase code coding, hoʻohana ʻia ka hoʻololi pae ma waenakonu o kēlā me kēia hōʻailona no ka hoʻonohonoho ʻana, a inā he hoʻololi hou i ka hoʻomaka ʻana o kēlā me kēia hōʻailona e hoʻohana ʻia e hoʻoholo i ke code hōʻailona. Inā he hoʻololi, ʻo ia hoʻi ka binary “1″, a inā ʻaʻohe hoʻololi, ʻo ia ka binary “0″. Hoʻohana pinepine ʻia kēia code ma nā pūnaewele wahi kūloko.
CMI code
ʻO ka CMI code ka pōkole o "mark inversion code. E like me ke code bi-phase, he code bipolar ʻelua pae. ʻO ka lula coding ʻo ia: “1″ code ua hōʻike ʻia e “11″ a me “00″ helu helu ʻelua; Ua hōʻike paʻa ʻia ke code “0″ e “01″, a ua hōʻike ʻia kona ʻano nalu ma ke Kiʻi 6-5(c).
He maʻalahi ka hoʻokō ʻana i nā code CMI a loaʻa i ka ʻike manawa waiwai. Eia kekahi, no ka mea, he hui code pāpā ʻia ʻo 10, ʻaʻole e ʻoi aku ma mua o ʻekolu mau code consecutive, a hiki ke hoʻohana ʻia kēia lula no ka ʻike hewa macroscopic. Ua ʻōlelo ʻia kēia code e ITU-T ma ke ʻano he ʻano code interface o ka PCM quartet a hoʻohana ʻia i kekahi manawa i nā ʻōnaehana hoʻoili uila optical me ka helu haʻahaʻa ma mua o 8.448Mb/s.
Hoʻopaʻa paʻapili
No ka hoʻomaikaʻi ʻana i ka hana coding laina, koi ʻia kekahi ʻano redundancy e hōʻoia i ka hoʻonohonoho hoʻonohonoho ʻana a me ka ʻike hewa. Hiki i ka hoʻokomo ʻana i ka coding block ke hoʻokō i kēia mau kumu ʻelua i kekahi ʻano. ʻO ke ʻano o ka coding block he code nBmB, code nBmT a pēlā aku.
ʻO ke code nBmB kekahi ʻano o ka poloka coding, nāna e hoʻokaʻawale i ke code binary n-bit o ke kahawai ʻike kumu i loko o kahi hui a hoʻololi iā ia me kahi pūʻulu code hou o ka m-bit binary code, kahi m>n. Mai ka m>n, aia paha ka hui code hou Aia he 2^m hui, no laila ua nui aku (2^m-2^n) hui. Ma waena o nā hui 2″, koho ʻia ka pūʻulu code maikaʻi ma kekahi ʻano e like me ka pūʻulu code i ʻae ʻia, a hoʻohana ʻia ke koena e like me ka pūʻulu code pāpā ʻia e loaʻa ai ka hana coding maikaʻi. No ka laʻana, ma 4B5B coding, hoʻohana ʻia ka code 5-bit ma kahi o ka code 4-bit. Hoʻopili, no ka hui 4-bit, aia wale nō 2^4=16 hui like ʻole, a no ka hui pū ʻana 5-bit, aia 2^5=32 hui like ʻole. I mea e hoʻokō ai i ka hoʻonohonoho ʻana, ʻaʻole hiki iā mākou ke hahai ma mua o hoʻokahi alakaʻi "0" a me ʻelua suffixes "0" i hoʻohana ʻia e koho i nā pūʻulu code, a ʻo ke koena he mau pūʻulu code disable. Ma kēia ʻano, inā ʻike ʻia kahi pūʻulu code disable ma ka hopena e loaʻa ai, ʻo ia ka mea aia kahi hewa i ke kaʻina hoʻouna, a laila e hoʻomaikaʻi ai i ka hiki ke ʻike hewa o ka ʻōnaehana. Hiki ke manaʻo ʻia nā code bi-phase a me nā code CMI e like me nā code 1B2B.
Ma ka ʻōnaehana kamaʻilio fiber optical, koho pinepine ʻia ka m=n+1, a lawe ʻia ke code 1B2B, 2B3B code, 3B4B code a me 5B6B code. Ma waena o lākou, ua hoʻohana maʻalahi ʻia ke ʻano code code 5B6B ma ke ʻano he kumu hoʻohālikelike laina laina no ka hui ʻekolu a me ka hui ʻehā a i ʻole.
Hāʻawi ka code nBmB i ka hoʻonohonoho maikaʻi a me nā hana ʻike hewa, akā uku pū kekahi i kekahi kumukūʻai, ʻo ia hoʻi, e hoʻonui ʻia ka bandwidth e pono ai.
ʻO ka manaʻo hoʻolālā o ka code nBmT e hoʻololi i nā code binary i kahi pūʻulu code hou o nā code m ternary, a me m
ʻO ka mea i luna nei he wehewehe ʻana i nā wahi ʻike o ka "Common Code Types for Baseband Transmission" i lawe ʻia e Shenzhen Hi-Diwei Optoelectronics Technology Co., Ltd., manaʻo wau e hiki i kēia ʻatikala ke kōkua iā ʻoe e hoʻonui i kou ʻike. Ma waho aʻe o kēia ʻatikala inā ʻoe e ʻimi nei i kahi ʻoihana mea hana uila fiber optical maikaʻi āu e noʻonoʻo aie pili ana iā mākou.
ʻO Shenzhen HDV photoelectric Technology Co., Ltd. ka mea hana nui i nā huahana kamaʻilio. I kēia manawa, uhi nā mea hana i hana ʻia i kamoʻo ONU, moʻo module optical, OLT moʻo, amoʻo transceiver. Hiki iā mākou ke hāʻawi i nā lawelawe kūikawā no nā hiʻohiʻona like ʻole. Aloha oekukakuka.
