Nws qhia me ntsis ntau attenuation tshaj qhov ncaj qha teeb liab, tab sis muaj ib tug tseem ceeb heev khoom vaj khoom tsev: lub teeb liab reflected ntawm lub hlws ris tsis propagate raws tib axis raws li lub ntsiab teeb liab, vim hais tias nws muaj tsawg zog rau nws. Rau cov tshuab xa xov hluav taws xob nrog cov khoom siv rov ua dua thiab kho dua tshiab, qhov no zoo li tsis tseem ceeb, tab sis lub teeb liab TV pib nws txoj kev taug kev raws li cov teeb liab analog (hauv fiber ntau optics ib yam), thiab rau nws qhov no yog qhov tseem ceeb heev: txhua tus neeg nco txog lub dab lossis duab. nkag mus rau hauv cov TV qub nrog kev txais tos tsis meej. Zoo li nthwv dej tshwm sim tshwm sim ob qho tib si saum huab cua thiab hauv cov kab hluav taws xob. Lub teeb liab TV digital, txawm hais tias nws tau nce lub suab nrov tiv thaiv, txawm li cas los xij tsis muaj ntau qhov txiaj ntsig ntawm cov ntaub ntawv xa mus thiab tuaj yeem raug kev txom nyem ntawm qib physics, tab sis tsis tuaj yeem rov qab los ntawm kev thov rov qab.
Yuav kom lub teeb liab kis tau los ntawm qhov tseem ceeb, yuav tsum muaj qib siab, yog li amplifiers yog qhov tseem ceeb hauv cov saw hlau. Lub teeb liab kho qhov muag hauv CATV cov tshuab tau nthuav dav los ntawm erbium amplifiers (EDFA). Kev khiav hauj lwm ntawm cov cuab yeej no yog ib qho piv txwv zoo ntawm yuav ua li cas ib qho kev siv tshuab txaus txaus yog qhov txawv ntawm cov khawv koob. Nyob rau hauv ib tug nutshell: thaum ib tug beam dhau los ntawm ib tug fiber doped nrog erbium, tej yam kev mob yog tsim nyob rau hauv uas txhua photon ntawm tus thawj hluav taws xob tsim ob clones ntawm nws tus kheej. Cov khoom siv zoo li no tau siv rau hauv txhua qhov kev sib kis cov ntaub ntawv nyob rau hauv qhov ntev. Lawv yeej tsis pheej yig. Yog li ntawd, nyob rau hauv cov ntaub ntawv uas lub teeb liab amplification los ntawm ib tug tseem ceeb npaum li cas yog tsis yuav tsum tau thiab tsis muaj kev txwv nruj rau lub suab nrov, cov teeb liab regenerators yog siv:
Cov cuab yeej no, raws li tau pom los ntawm daim duab thaiv, ua ob lub teeb liab hloov dua siab tshiab ntawm optical thiab hluav taws xob xov xwm. Qhov kev tsim no tso cai rau koj hloov lub teeb liab wavelength yog tias tsim nyog.
Xws li manipulations raws li lub teeb liab amplification thiab regeneration yog tsim nyog tsis tsuas yog los them nyiaj rau kilometer-ntev cable attenuation. Qhov kev poob loj tshaj plaws tshwm sim thaum lub teeb liab sib faib ntawm cov ceg hauv network. Kev faib tawm yog nqa tawm siv cov khoom siv passive, uas, nyob ntawm qhov xav tau, tuaj yeem muaj tus lej sib txawv ntawm cov kais dej, thiab tseem tuaj yeem faib cov teeb liab los yog tsis sib xws.
Sab hauv, qhov sib faib yog cov fibers txuas los ntawm sab nrauv, lossis etched, zoo li cov kab ntawm cov ntawv luam tawm. Yuav kom nkag mus tob dua, kuv pom zoo cov ntawv NAGru txog welded ΠΈ kev npaj division raws li. Qhov ntau taps lub divider muaj, ntau attenuation nws qhia rau hauv lub teeb liab.
Yog tias peb ntxiv cov ntxaij lim dej rau lub splitter cais cov kab teeb nrog cov wavelengths sib txawv, ces peb tuaj yeem xa ob lub teeb liab ib zaug hauv ib qho fiber ntau.
Qhov no yog qhov yooj yim version ntawm optical multiplexing - FWDM. Los ntawm kev sib txuas CATV thiab cov khoom siv hauv Is Taws Nem rau TV thiab Express inputs, feem, peb yuav tau txais cov teeb liab sib xyaw ua ke hauv COM tus pin, uas tuaj yeem kis tau los ntawm ib qho fiber ntau, thiab nyob rau sab nraud nws kuj tuaj yeem muab faib ua cov khoom siv kho qhov muag thiab piv txwv li switch. Qhov no tshwm sim zoo ib yam li zaj sawv tshwm los ntawm lub teeb dawb hauv iav prism.
Rau lub hom phiaj ntawm optical teeb liab backup, ntxiv rau optical receivers nrog ob inputs, uas kuv tau sau txog hauv qhov kawg ib qho electromechanical relay tuaj yeem siv tau, uas tuaj yeem hloov ntawm ib qho mus rau lwm qhov raws li cov teeb liab tsis tau teev tseg.
Yog tias ib qho fiber ntau degrades, lub cuab yeej yuav hloov mus rau lwm qhov. Lub sijhawm hloov pauv tsawg dua li ib thib ob, yog li rau cov neeg siv khoom nws zoo li qhov phem tshaj plaws xws li ib txhais tes ntawm artifacts ntawm cov duab digital TV, uas tam sim ntawd ploj mus nrog tus ncej tom ntej.