hom kav hlau txais xov ntau tshaj plaws hauv kev siv niaj hnub no yog RF coaxial cable. Nws yog qhov yooj yim thiab muab qib zoo ntawm kev ua haujlwm. Vim li no, coob tus coaxial cables yog tsim rau ntau lub hom phiaj.
Uss
Cables ntawm hom no yog siv rau qhov tsim nyog xa xov tooj cua zaus hluav taws xob teeb liab. Lawv qhov pom tseeb tshaj plaws ntawm kev siv yog tshaj tawm cov duab rau hauv TV hauv tsev, tab sis lawv xav tau hauv ntau qhov chaw. Coaxial cables kuj tseem siv rau kev soj ntsuam video thiab kev sib txuas ntawm cov txais thiab kav hlau txais xov los ntawm cov neeg siv khoom lag luam thiab kev lag luam. Lawv xav tau qhov uas yuav tsum tau xa cov teeb liab ntau zaus hla qhov deb.
Kev tsim ntawm coaxial cables txo qis thiab cuam tshuam. Yog li ntawd, lawv tau dav siv nyob rau hauv lub koom haum ntawm kev sib txuas network. Piv txwv li, digital coaxial cables tau siv thaum ntxovCov ntaub ntawv ntawm Ethernet hauv cheeb tsam network, txawm hais tias niaj hnub no lawv tau hloov los ntawm cov fibers kho qhov muag kom ceev cov ntaub ntawv hloov pauv thiab pheej yig dua twisted khub thaum lub teeb liab zaus tsis siab.
History of Creation
RF coaxial cable yog ib feem tseem ceeb ntawm cov khoom siv hluav taws xob niaj hnub no. Thawj qhov kev siv ntawm nws tshwm sim nyob rau hauv 1884, thaum Ernst von Siemens (ib tug ntawm cov founders ntawm Siemens) patented nws lub tswv yim, tab sis lub sij hawm ntawd tsis muaj daim ntawv thov rau nws. Nws tsis yog txog xyoo 1929 uas Tswb Laboratories patented niaj hnub coj mus muag coaxial cables, txawm hais tias lawv siv me me. Piv txwv li, lawv tau siv xyoo 1934 los xa cov duab hauv TV los ntawm Berlin Olympics mus rau Leipzig. Xyoo 1936, ib coaxial cable rau 40 kev sib txuas xov tooj tau muab tso rau ntawm London thiab Birmingham, thiab hauv Tebchaws Meskas, ntawm New York thiab Philadelphia, ib txoj kab sim tau tsim los xa cov duab hauv TV.
Tom qab pib kev lag luam siv, lwm yam kev siv tau raug tshawb pom uas tsim tau zoo thiab siv dav hauv kev lag luam thiab hauv tsev.
coaxial cable yog dab tsi?
Nws zoo li cov hlua hluav taws xob tuab. Tsim los ntawm cov khoom uas muab cov tsis tshua muaj RF teeb liab kis tau tus mob. Nws cov ntsiab lus tseem ceeb yog:
- tus neeg xyuas pib;
- insulating dielectric;
- sab nraum zoov;
- outer container.
Lub chaw tus neeg xyuas pib yuav luag ib txwm ua los ntawm tooj liab. Qee zaum siv tooj liab lossis aluminium alloy. Tej zaum yuav muaj ib lossis ntau cov xov hlau.
Insulating dielectric cais cov conductors thiab yog ib qho ntawm cov laj thawj tseem ceeb ntawm cov teeb liab attenuation. Tej zaum yuav muaj zog los yog ib nrab cua. Nws yog nqa tawm nyob rau hauv daim ntawv ntawm cov raj ntev ua los ntawm polyethylene los yog fluoroplastic, los yog ua npuas ncauj, feem ntau yog huab cua.
Cov neeg xyuas sab nrauv feem ntau yog tooj liab braid. Qhov no muab cov coaxial twisted cable nrog txaus yooj. Qee zaum 2 lossis 3 txheej yog siv los txhim kho kev tiv thaiv. Qhov no feem ntau yog ua tiav los ntawm kev tso ib lub braid ncaj qha rau lwm qhov, txawm hais tias tooj liab ntawv ci los yog daim kab xev yuav siv tau rau qee kis. Nrog rau kev siv cov khaubncaws sab nraud povtseg ntxiv, kev cuam tshuam thiab hluav taws xob tau txo qis.
Lub plhaub tiv thaiv sab nraud tiv thaiv kev tsim cov kab mob tawm tswv yim. Nws kuj tseem muab kev tiv thaiv kev nkag mus ntawm av thiab ya raws, thiab tiv thaiv kev puas tsuaj rau cable los ntawm lwm yam kev siv tshuab.
Txoj Cai Ua Haujlwm
Coaxial cable ua tam sim no los ntawm ob qho tib si sab hauv thiab sab nraud. Cov tam sim no sib npaug thiab muaj qhov sib txawv polarity, vim tias txhua qhov chaw nyob hauv lub cable, tsis txhob tawg dhau nws thiab tsis raug cuam tshuam. Yog li ntawd, tsis muaj cov khoom sab nraud cuam tshuam rau cov teb. Yog li, coaxial feeder yog qhov zoo tagnrho rau kev teeb tsa sab hauv lossis ze ntawm cov tsev lossis lwm yam khoom. Qhov no yog nws lub ntsiab kom zoo dua piv rau, piv txwv li, twisted khub.
Thaum xaiv hom coaxial cable, nws cov kev qhia tshwj xeeb thiab qhov ntsuas yuav tsum raug coj mus rau hauv tus account.
Impedance
Tus yam ntxwv tseem ceeb tshaj plaws ntawm coaxial cable yog nws impedance, uas yog txiav txim los ntawm nws txoj kab uas hla thiab dielectric khoom. Parameter yog ntsuas hauv ohms. Nws lub ntsiab lus feem ntau yog:
- 50 ohm coaxial cable. Muab cov teeb liab tsawg tsawg rau qhov hnyav ntawm tus neeg xyuas pib. Feem ntau siv rau cov hom phiaj kev tshaj lij.
- 75 ohm coaxial cable. Nws muaj qhov hnyav tsawg kawg nkaus rau ib theem ntawm kev poob. Siv dav hauv TV hauv tsev thiab khoom siv Hi-Fi.
- Lub 93 ohm cable yav dhau los yog siv los txuas cov khoos phis tawj thiab txuas cov saib.
Lwm qhov txiaj ntsig ntawm impedance muaj, tab sis lawv tsawg dua hauv kev thov.
Lwm qhov tseem ceeb ntawm lub coaxial twisted cable yog nws cov teeb liab kis tau tus mob. Lawv qib nyob ntawm ntau yam, nrog rau qhov zoo ntawm cov khoom siv dielectric thiab cov neeg xyuas pib. Lub teeb liab attenuation yog proportional rau cable ntev. Specifications feem ntau lub xeev poob hauv decibels ib chav tsev ntev. Piv txwv li, RG-6A / U coaxial cable muaj qhov attenuation ntawm 1.0 dB / 10 m ntawm 100 MHz. Hmoov tsis zoo, tsis yog txhua tus neeg tsim khoom siv tib lub sijhawm ntev, yog li kev suav ntxiv yuav xav tau rau kev sib piv.
siab tshaj lub zog
Txawm hais tias qhov kev qhia tshwj xeeb no tsis tseem ceeb heev rau cov ntawv thov teeb liab tsawg, nws tuaj yeem dhau los ua teeb meem thaum xa hluav taws xob siab. Feem ntau, cov kev txwv tshwm sim vim qhov kub poob hauv lub cable. Yog xav tau kev xa hluav taws xob siab, xyuas qhov kev khiav hauj lwm voltage.
Shortening factor
Qhov no yog qhov piv ntawm cov teeb liab kis ceev hauv coaxial cable mus rau qhov nrawm ntawm nws qhov kev nthuav tawm hauv lub tshuab nqus tsev (qhov ceev ntawm lub teeb).
Qee qhov xwm txheej, tus nqi ntawm qhov nrawm nrawm tuaj yeem yog qhov tseem ceeb, piv txwv li, thaum theem ntawm lub teeb liab tseem ceeb. Nws yog ib txwm tsawg dua 1. Nyob rau hauv ntau yam, nws yog txiav txim los ntawm cov khoom ntawm dielectric. Rau cov coaxial cables nrog cov khoom polyethylene dielectric, qhov shortening yam yog 0.66, thiab nrog polyethylene ua npuas ncauj - nyob rau hauv qhov ntau ntawm 0.80-0.88.
Muaj peev xwm
Vim tias cov conductors sab hauv thiab sab nrauv tsim muaj peev xwm, nws yog proportional rau lawv cov diameters, cable ntev, thiab dielectric tas li.
Max voltage
Qee zaum, qhov hluav taws xob nce mus txog qhov muaj nuj nqis siab. Vim li no, lub cable yuav poob. Qhov hluav taws xob nce siab vim yog qhov siab ntawm qhov sawv tsis muaj zog thiab lub zog siab. Ua ntej xaiv ib hom coaxial cable, nws yog ib qho tsim nyog los xyuas seb nws tiv taus qhov kev cia siab npaum li cas.
Lub cev qhov ntev
tus yam ntxwv no tseem ceeb rau ntau yam. conductorsCov kab uas loj dua feem ntau muaj qhov poob qis dua thiab muaj zog ntau dua. Piv txwv li, nrov 75 ohm RG-6 / U coaxial cable muaj ib txoj kab uas hla ntawm 6.86 hli.
Ntxiv rau, lub cable yuav tsum phim qhov muaj qhov ntau thiab tsawg thiab phim hom plugs kom raug. Feem ntau tom kawg yog ua kom haum hom kab nrov.
Installation Guide
RF coaxial cable yog dav siv los xa cov teeb liab los ntawm transmitter lossis receiver. Txawm hais tias nws yooj yim heev rau nruab, txhawm rau kom nws kav ntev, qee yam yuav tsum tau ua. Qhov no yog qhov tseem ceeb tshwj xeeb vim nws feem ntau ntsia sab nraum zoov thiab yuav tsum tiv taus ib puag ncig hnyav.
Tej yam xws li dej noo tuaj yeem ua rau nws cov txiaj ntsig zoo dhau sijhawm. Xws li ib tug txo mus rau unnoticed mus txog rau thaum nws mus txog qhov twg nws yuav siv tsis tau. Qee qhov kev ceev faj yooj yim yuav ua rau koj cov coax cable ua haujlwm tau zoo thiab ua rau qeeb qeeb cable degradation.
Xaiv xaj
Muaj ntau yam ntawm coaxial cables ntawm lub khw, thiab thaum xub thawj siab ib muag, kev xaiv yuav zoo li nyuaj. Thawj qhov kev txiav txim siab yuav tsum tau ua yog xaiv qhov haum impedance. Tsev Hi-Fi thiab video kav hlau txais xov siv 75 ohm coaxial cable. Cov kws tshaj lij thiab cov kws tshaj lij xov tooj cua feem ntau xaiv 50 ohm impedance.
Qhov kev txiav txim siab tom ntej yuav ua yog theem ntawm lub teeb liab attenuation uas tau txais. Yuav ua li castsawg poob, qhov loj ntawm txoj kab uas hla ntawm lub cable, nrog rau nws cov nqi. Feem ntau, koj tuaj yeem pom ntau lub npe nrog cov yam ntxwv zoo ib yam, thiab feem ntau qhov kev txiav txim siab ntawm ib hom tshwj xeeb yuav nyob ntawm txoj haujlwm ntawm cov neeg muag khoom.
Thaum pom cov kab tsim nyog tau pom, nws tuaj yeem yuav thiab nruab.
Tiv thaiv los ntawm huab cua phem
Thaum kev teeb tsa sab nraum zoov, piv txwv li, coaxial cable rau kev soj ntsuam video, nws tseem ceeb heev kom ntseeg tau tias nws muaj kev tiv thaiv zoo. Qhov no yog qhov tseem ceeb heev, vim tias txhua qhov dej noo yuav ua rau muaj kev poob loj. Yog hais tias lub dielectric sib cais cov sab hauv thiab sab nrauv conductors tau ntub, qhov no yuav degrade nws cov kev ua tau zoo thiab nce attenuation. Cov av noo kuj oxidizes lub braid thiab txo nws cov conductivity.
Yog vim li cas nws tseem ceeb heev kom kaw qhov kawg ntawm lub cable yog tias nws siv sab nraum zoov thiab ua kom tsis muaj dej noo. Nws yog ib qho tsim nyog los xyuas kom meej tias lub plhaub sab nraud tseem nyob ruaj khov thiab tsis puas thaum lub sijhawm teeb tsa thiab ua haujlwm ntxiv.
Ib txoj hauv kev ntxiv los tiv thaiv cov dej noo ntau los ntawm kev nkag mus rau hauv lub cable yog tsim lub voj voog nce thiab nqis. Qhov no tiv thaiv cov dej uas tau nkag mus rau hauv los ntawm kev txav mus los. Txawm li cas los xij, cov dej noo tseem yuav kis tau los ntawm kev ua capillary, yog li nws yog qhov zoo tshaj plaws los xyuas kom meej tias qhov kawg tau raug kaw thiab tiv thaiv.
Cov lus pom zoo rau kev teeb tsa dav dav
Txhua cov kab hluav taws xob muaj lub vojvoog khoov. Txhawm rau tiv thaiv kev puas tsuaj, lawv yuav tsum tsis txhob khoov ntau dua li tus nqi no. Lwm yamHauv qhov no, cov qauv sab hauv tuaj yeem raug puas tsuaj thiab poob yuav nce ntxiv.
Koj yuav tsum tau saib xyuas kom tsis txhob muaj kab mob. Qhov no yuav ua rau muaj kev hloov pauv ntawm nws qhov loj thiab yoj tsis kam. Tsis tas li ntawd, kev puas tsuaj rau lub dielectric tuaj yeem nce qib ntawm kev poob.
Yog hais tias lub cev puas lawm, xyuas kom meej tias nws cov ntaub qhwv tsis zoo. Yog tias nws txoj kev ncaj ncees tawg lawm, qhov no tuaj yeem ua rau nkag mus ntawm cov dej noo, oxidation ntawm cov hlau thiab ntub dej ntawm dielectric, uas yuav ua rau kom poob qis.
Qee zaum, cov coaxial cable yuav tsum tau muab faus. Cov thwj cim tsis tuaj yeem muab tso rau hauv av, vim lawv lub plhaub tsis yog tsim los rau cov xwm txheej no. Tab sis lawv tuaj yeem muab tso rau hauv ib qho channel tshwj xeeb tsim rau qhov no. Qhov no muaj qhov zoo dua uas lub cable yog yooj yim los hloov. Txawm li cas los xij, nco ntsoov tias tsis muaj dej nkag mus rau hauv cov channel. Lwm txoj hauv kev yog siv lub cable tshwj xeeb tsim los tso rau hauv av, cov ntaub qhwv uas tuaj yeem tiv taus cov xwm txheej zoo li no.
End
Thaum txhim kho lub coaxial cable, nws yog ib qho tseem ceeb kom txiav nws kom raug. Feem ntau, qhov kev txiav tawm lub cev yog lub ntsaws thiab qhov kawg ntaus ntawv yog tus kav hlau txais xov lossis lub receiver. Kev sib txuas yuav tsum ua kom raug thiab ua tau zoo.
Txawm hais tias cov chaw txuas hauv tsev feem ntau muaj kev ua haujlwm tsis zoo RF, muaj ob peb txoj hauv kev. Kev sib txuas zoo dua yog xav tau rau kev siv tshaj lij, txawm hais tias qhov no koj yuav tsum tau ua kom paub tseeb tiastias lawv tsim nyog rau cov zaus siv. Qee cov qauv pheej yig tsis ua raws li qhov yuav tsum tau ua thiab txo qis kev ua haujlwm ntawm coaxial cable. Yog li ntawd, nws yog qhov zoo dua los yuav cov khoom sib txuas los ntawm cov neeg muag khoom ntseeg siab.
Kev teeb tsa ntawm lub coaxial cable yuav muab ntau xyoo kev pabcuam. Txawm li cas los xij, hnav thiab tsim kua muag thiab ib puag ncig cuam tshuam yuav ua rau nws yuav tsum tau hloov tom qab ib ntus. Vim tias kev ua haujlwm tsis zoo tshwm sim maj mam, nws yuav tsis pom. Nws tshwm sim tsuas yog tom qab hloov tag nrho cov cable.
