Tam sim no txhais tau tias thiab kev sib txuas lus pab peb tsis yog tsuas yog cov neeg nruab nrab rau kev hloov cov ntaub ntawv. Lawv muaj peev xwm muab thiab tswj xyuas cov txheej txheem thiab cov cuab yeej siv, saib xyuas kev ua haujlwm ntawm cov neeg ua haujlwm, thiab tswj cov cuab yeej siv nyob deb.
Ntau tau hais txog hom kev sib txuas lus. Peb yuav cia li sau lawv. Yog li, xov tooj, xov tooj, xov tooj cua sib txuas lus, suab tshaj tawm xov xwm, TV, satellite lossis mobile kev sib txuas lus, hom tshiab (3G, 4G, thiab lwm yam), computer wired thiab wireless networks tuaj yeem siv rau kev xa cov ntaub ntawv. Nyob rau tib lub sijhawm, ua tsaug rau kev txhim kho cov thev naus laus zis hauv kev sib txuas lus thiab kev hloov pauv, qhov zoo thiab ceev ntawm kev sib kis tau loj hlob tas li. Kev sib txuas lus channel ua lub luag haujlwm tseem ceeb hauv qhov no. Lawv yuav sib tham.
Hom thiab kev faib tawm ntawm kev sib txuas lus
Ua ntej tham txog hom, nws ua rau kev nkag siab los txhais lub ntsiab lus ntawm lub tswv yim ntawm "kev sib txuas lus". Nws txhais tau hais tias lub kaw lus uas muaj ib puag ncig uas cov teeb liab nthuav tawm, nrog rau cov khoom siv thev naus laus zis thiab txhais tau tias muab thiab tswj kev nthuav tawm ntawm lub teeb liab ntawm qee zaus ntawm qee qhov ceev.
Raws li kev faib tawm lossis kev sau ntawv, cestam sim no, kev sib txuas lus tau muab faib raws li hauv qab no:
- Los ntawm hom khoom nruab nrab (cable lossis RF).
- Los ntawm zaus band (HF, VHF, UHF, microwave, millimeter yoj, infrared).
- Los ntawm hom teeb liab (analogue lossis digital).
Ntau tus neeg tej zaum tau hnov cov lus hais xws li kev sib txuas lus digital lossis kev sib txuas lus kho qhov muag. Dab tsi yog lawv qhov txawv los yog txiaj ntsig?
Cov kev sib txuas lus digital xa cov ntaub ntawv hauv daim ntawv binary code, uas
tsuas yog muaj 0 thiab 1 xwb. Ua tsaug rau cov thev naus laus zis no, nws muaj peev xwm ua tiav cov ntaub ntawv tsawg tsawg lossis cuam tshuam, tsis zoo li cov qauv analog. Piv txwv li, thaum tham hauv xov tooj, nws yog lub teeb liab analog uas feem ntau siv, lub hauv paus ntsiab lus ntawm kev xa xov hluav taws xob tsis tu ncua oscillations. Yog vim li cas cov tshuab kev sib txuas lus analog tau raug cuam tshuam rau kev cuam tshuam thiab tuaj yeem cuam tshuam cov ntaub ntawv lossis poob cov ntaub ntawv.
Kev sib txuas lus kho qhov muag sib txawv ntawm lwm tus los ntawm cov khoom siv los ntawm cov khoom siv cable. Optical fiber ntau siv nyob rau hauv lawv cov khoom tso cai rau siab channel bandwidth, tsawg distortion los yog txo cov teeb liab txawm nyob deb deb, thiab tiv thaiv kev cuam tshuam. Tsis tas li ntawd, fiber ntau optical yog kev lag luam rau kev tsim khoom, ntau me thiab sib zog nyob rau hauv tag nrho qhov ntev. Raws li qee qhov chaw, qhov hnyav ntawm cov pa cables tuaj yeem yog 10 npaug ntawm cov xaim kho qhov muag.zoo sib xws. Kev sib txuas lus kho qhov muag kuj tseem yog digital, vim lawv xa cov ntaub ntawv hauv daim ntawv no.
Ib tus tsis tuaj yeem tab sis hais txog kev sib txuas lus wireless. Peb siv ib co ntawm lawv tsis txawm xav txog nws. Ib qho piv txwv ntawm qhov no yuav yog infrared (laser) kev sib txuas lus channel. Nws yog nws tus uas tso cai rau peb tswj lub TV lossis lwm yam khoom siv uas siv cov chaw taws teeb tswj uas muab lub teeb taw qhia ntawm lub teeb. Wireless channels suav nrog:
- Infrared lossis laser.
- Microwave channels (siv rau kev sib txuas lus satellite lossis kev sib txuas mus ntev).
- Networks ntawm cov xov tooj cua dawb frequencies (lub peev xwm los xa cov teeb liab hauv ob peb pawg ib zaug).
