Ob qhov kev txhim kho tseem ceeb hauvfiber optic kev sib txuas lusyog qhov nce hauv kev sib kis tus nqi thiab qhov txuas ntxiv ntawm kev sib kis deb. Raws li kev sib kis tus nqi nce, cov yam tseem ceeb uas txwv qhov kev ncua deb ntawm lub teeb liab kis tau tus mob ntau dua, xws li chromatic dispersion, non-linear cuam tshuam, polarization hom dispersion, thiab lwm yam, uas tseem cuam tshuam rau tib lub sijhawm nce ntawm ob qho tib si. Tsis tas li ntawd tsis muaj qhov zoo tshaj plaws digital channel hauv cov txheej txheem xa tawm tiag tiag, lub teeb liab yuav ib txwm muaj aberrations thiab qeeb hauv cov txheej txheem sib kis ntawm ntau yam xov xwm, uas txhais tau hais tias yuam kev codes thiab jitter. Txhawm rau txo qhov cuam tshuam ntawm cov teeb meem tsis zoo no, cov kws tshaj lij hauv kev lag luam tau thov Forward Error Correction, lossis FEC (Forward Error Correction) luv luv.
FEC yog luv rau Forward Error Correction. Forward Error Correction yog ib hom kev ua yuam kev, uas yog hais txog cov txheej txheem uas lub teeb liab tau ua ua ntej raws li qee qhov algorithm rau coding ua ntej raug xa mus rau hauv cov kab sib kis, ntxiv cov lej tsis sib xws nrog cov yam ntxwv ntawm lub teeb liab nws tus kheej, thiab kev txiav txim siab. qhov tau txais cov teeb liab ntawm qhov kawg tau txais raws li qhov sib thooj algorithm, txhawm rau txhawm rau paub cov lej yuam kev tsim tawm thaum lub sijhawm sib kis thiab kho lawv. Txhawm rau muab ib qho piv txwv yooj yim, ib tus neeg sau ib tsab xov xwm nrog ntau tus typos hauv nws, tom qab ntawd tus neeg paub paub tseeb uas tuaj yeem nyeem nws, tom qab ntawd kho qhov typos thiab tom qab ntawd qhia rau tus neeg ua haujlwm. Ua ntej kev kho, tus neeg ua haujlwm tsis tuaj yeem nyeem nws, thiab tsuas yog tom qab tus neeg txheeb xyuas tau kho qhov typos tuaj yeem nyeem nws.
FEC yog haum rau kev sib txuas lus ceev (40G thiab 100G), lub teeb liab kho qhov muag deteriorates thaum kis tau tus mob vim muaj ntau yam, ua rau mis-coding ntawm qhov kawg tau txais, uas tej zaum yuav misjudge. "1" teeb liab raws li "0" teeb liab los yog "0" teeb liab raws li "1" teeb liab, FEC muaj nuj nqi muaj cov ntaub ntawv code nrog tej yam kev ua yuam kev kho muaj peev xwm los ntawm lub channel coder nyob rau hauv lub xa kawg, thiab lub channel decoder ntawm qhov kawg decodes cov code tau txais. Yog hais tias tus naj npawb ntawm qhov yuam kev tsim nyob rau hauv kev sib kis yog nyob rau hauv qhov kev ua yuam kev kho muaj peev xwm (tsis txuas ntxiv ua yuam kev), tus decoder yuav nrhiav thiab kho qhov yuam kev txhawm rau txhim kho qhov zoo ntawm cov teeb liab.
