Indlela Yokuthola Amaphutha: Ukugcina Ubuqotho Bedatha Ezinhlelweni Zokuxhumana
I-Pendahuluan
Ngokukhula okusheshayo kobuchwepheshe kanye nokuxhumana kwedijithali, ukubaluleka kokugcina ubuqotho bedatha akunakugcizelelwa. Kunoma yiluphi uhlelo lokuxhumana, kungakhathaliseki ukuthi ukudluliselwa kwedatha ngenethiwekhi yekhompyutha, ukugcinwa kwedatha yedijithali, noma ukudluliselwa kwesignali kwezokuxhumana, ukuqinisekisa ukuthi idatha etholiwe ifana ncamashi nedatha ethunyelwe kubalulekile. Izindlela zokuthola amaphutha ziwumgogodla wokulondoloza lobu buqotho bedatha, okuyisisekelo ekuzinzeni nasekuthembekeni kobuchwepheshe obuningi esibusebenzisa namuhla.
Ukubaluleka Kokuthola Amaphutha
Amaphutha ekudlulisweni kwedatha angabangelwa yizinto ezahlukahlukene, okuhlanganisa ukuphazamiseka kwe-electromagnetic, ukuphazamiseka kwesignali, ukwehluleka kwehadiwe, noma amaphutha kwimidiya yokudlulisa. La maphutha angahluka kusukela kuma-bits abuyiselwe emuva, angekho, noma angeziwe. Ngaphandle kwezindlela ezifanele zokuthola la maphutha, idatha edlulisiwe ingonakala futhi ibangele amaphutha abulalayo ezinhlelweni zokusebenza ezithembele kuyo. Isibonelo, ukudluliselwa kwamafayela, ukuxhumana phakathi kweseva neseva, ngisho nokusebenza kwezezimali kungaba sengozini.
Izinhlobo Zamaphutha Kudatha
1. Iphutha Lebhithi Elilodwa
Iphutha le-single-bit lenzeka lapho i-bit eyodwa yedatha ishintsha kusuka ku-0 iye ku-1 noma ngokuphambene nalokho. Leli yiphutha elilula kakhulu ukulithola nokulilungisa.
2. Amaphutha Okuqhuma
Amaphutha okuqhuma ayenzeka lapho iqembu lama-bits alandelanayo kudatha linephutha. Lokhu kuqhuma kungahluka ngobude futhi kuvame ukuba nzima ukukubona nokulungisa kunamaphutha e-single-bit.
3. Amaphutha Aphindaphindwayo
Iphutha eliphindaphindayo uhlobo lwephutha elivela ngokuphindaphindiwe endaweni efanayo yebhithi kumabhulokhi amaningi edatha.
Amasu Okuthola Amaphutha
1.Parity Hlola
Indlela yokuhlola i-parity iyindlela eyisisekelo yokuthola amaphutha e-single-bit. I-parity bit iyi-bit eyengeziwe engezwe kusethi yama-bit ukuqinisekisa ukuthi inani lama-1 kusethi lilingana (lilingana ngisho) noma lilingana (lilingana ngokungajwayelekile). Uma idatha itholakele, uhlelo lubala inani lama-1 futhi luqinisekisa ukuthi lifana ne-parity elindelekile. Uma kutholwa ukungafani, kuvele iphutha.
Isibonelo esilula: uma sinedatha engu-1101 futhi sisebenzisa i-even parity, sifaka i-bit eyengeziwe ukuze idatha edlulisiwe ibe ngu-11011 (ama-bits amane angu-1, inombolo elinganayo). Uma idatha etholiwe ingu-11001 (ama-bits amathathu angu-1, inombolo engavamile), khona-ke iphutha liyatholakala.
2. I-Checksum
I-Checksum iyindlela eyinkimbinkimbi yokuthola amaphutha evame ukusetshenziswa kumaphrothokholi enethiwekhi. Idatha ihlukaniswe ngezigaba, futhi inani eliphelele lesigaba ngasinye (i-checksum) liyabalwa. Le checksum ithunyelwa nedatha. Umamukeli ube esebala i-checksum yedatha etholiwe bese eyiqhathanisa ne-checksum etholiwe. Uma kukhona umehluko, kutholakala iphutha.
Le ndlela iphumelela kakhulu ekutholeni izinhlobo ezahlukene zamaphutha okuhlanganisa namaphutha okuqhuma.
3. Ukuhlolwa Kokuphindaphindeka Kwemisebenzi (CRC)
I-CRC ingenye yezindlela ezithandwa kakhulu zokuthola amaphutha ekudlulisweni kwedatha. Le ndlela isebenzisa i-algorithm yezibalo eyinkimbinkimbi kakhulu, lapho idatha ibhekwa njenge-polynomial enama-binary bese ihlukaniswa yi-polynomial yejeneretha. Umphumela walokhu kuhlukaniswa kuba yisisele, esaziwa ngokuthi ikhodi ye-CRC.
Uma idatha ithunyelwa ngekhodi ye-CRC, umamukeli wenza ukwahlukanisa okufanayo. Uma ukwahlukanisa kungaphumeli lutho, idatha itholwa kahle. Ngaphandle kwalokho, kutholakale iphutha.
4. Ikhodi yeHamming
Ikhodi ye-Hamming iyindlela engasetshenziswa nje kuphela ukuthola kodwa nokulungisa amaphutha e-single-bit. Ngokufaka i-parity bit endaweni ethile ngokulandelana kwama-data bits, umamukeli anganquma indawo eqondile ye-bit enephutha. Isibonelo, ikhodi ye-7,4 Hamming iguqula ama-bits angu-4 edatha abe ama-bits angu-7 ngokuhlanganisa ama-parity bits angu-3.
Uma kwenzeka iphutha kwenye yama-bits, umamukeli angayibona futhi ayilungise ngokushesha esebenzisa la ma-bits angafuneki.
5. Ikhodi kaReed-Solomon
I-Reed-Solomon Code iyindlela yokuthola nokulungisa amaphutha esetshenziswa kakhulu ezinhlelweni zokuxhumana zedijithali ezidinga ukubekezelela amaphutha aphezulu. Le ndlela imelelwa ukusetshenziswa kwe-polynomial phezu kwama-bits amaningi, okuvumela ukutholwa nokulungiswa kwamaphutha amade aqhumayo.
Ukuqhathaniswa Kwamasu Okuthola Amaphutha
| Ubuchwepheshe | Izinzuzo | Ukungalungi |
|——–|————|————-|
| Ukuhlola Ukulingana | Kulula, kuyashesha, futhi kusebenzisa kahle izinsiza. | Isebenza kahle kuphela ekutholeni amaphutha e-single-bit. |
| I-Checksum | Iqinile kakhulu kune-parity, ithola amaphutha amaningi ahlanganisa nokuqhuma. | Ayikwazi ukulungisa amaphutha, ithola wona kuphela. |
| CRC | Isebenza kahle kakhulu ekutholeni amaphutha e-single-bit kanye ne-burst. | Idinga ukubala okuyinkimbinkimbi kakhulu kune-checksum. |
| Ikhodi ye-Hamming | Ingathola futhi ilungise amaphutha e-single-bit. | I-overhead enkulu ngenxa yokwengezwa kwe-parity bit. |
| Ikhodi kaReed-Solomon | Iyakwazi ukubona nokulungisa amaphutha amaningi kubhulokhi yedatha. | Iyinkimbinkimbi kakhulu futhi idinga ukubalwa okwengeziwe. |
Ukusetshenziswa Empilweni Yansuku Zonke
Amasu okuthola amaphutha asetshenziswa ezicini ezahlukene zokuphila kwansuku zonke. Isibonelo, ekuxhumaneni kwamaselula, ama-CRC asetshenziswa ukuqinisekisa ukuthi izimpawu ezitholiwe azonakaliswa. Kumanethiwekhi ekhompyutha, amaphakethe edatha athunyelwayo akalwa kusetshenziswa ama-checksum nama-CRC ukuqinisekisa ukuthembeka kwawo. Ngisho nasezindaweni zokugcina izinto ezifana nama-CD nama-DVD, ama-Reed-Solomon Codes asetshenziswa ukulungisa amaphutha abangelwa ukuklwebheka noma ukulimala okungokomzimba kwidiski.
Isiphetho
Izindlela zokuthola amaphutha ziyingxenye ebalulekile yezinhlelo zokuxhumana zanamuhla. Kusetshenziswa amasu ahlukahlukene, kusukela ekuhlolweni okulula kokulingana kuya kumakhodi ayinkimbinkimbi kaReed-Solomon, ubuqotho bedatha bungaqinisekiswa naphezu kokuphazamiseka kokudluliselwa nokugcinwa. Ukuqonda nokusebenzisa kahle lawa masu kuyisinyathelo esibalulekile ekuqinisekiseni ukuthi izinhlelo zokuxhumana zedijithali zihlala zithembekile futhi zisebenza kahle, kugwenywe izinkinga ezingavela ngamaphutha edatha. Ezweni elincike kakhulu kubuchwepheshe bolwazi, indima yezindlela zokuthola amaphutha ayinakubukelwa phansi.
