Kwiingcali ezininzi zonxibelelwano, iikhonsepthi ezinje 'njengokubambezeleka kokusasaza' kunye 'nokulibazisa i-skew' zizisa iinkumbulo ezibuhlungu zeklasi yefiziksi yesikolo samabanga aphakamileyo.Enyanisweni, iimpembelelo zokulibaziseka kunye nokulibaziseka kwe-skew ekuhanjisweni komqondiso zicaciswa ngokulula kwaye ziyaqondwa.
Ulibaziseko yipropathi eyaziwayo ukuba ikhona kuzo zonke iindidi zothumelo losasazo.Ulibaziseko losasazo lulingana nenani lexesha elidlulayo phakathi kwaxa isignali ihanjiswa naxa ifunyenwe kwelinye icala lomjelo wekhebula.Umphumo ufana nokulibaziseka kwexesha phakathi kokubetha umbane kunye neendudumo ziviwa-ngaphandle kokuba iimpawu zombane zihamba ngokukhawuleza kunesandi.Elona xabiso lokulibaziseka kwi-twisted-pair cabling ngumsebenzi we-nominal velocity of propagation (NVP), ubude kunye nobuninzi.
I-NVP iyahluka ngokwemathiriyeli yedielectric esetyenziswa kwintambo kwaye ichazwa njengepesenti yesantya sokukhanya.Umzekelo, ulwakhiwo oluninzi lwecandelo 5 le-polyethylene (FRPE) lunoluhlu lwe-NVP ukusuka kwi-0.65cto0.70c (apho u-“c” umele isantya sokukhanya ~ 3 x108 m/s) xa kulinganiswa kwintambo egqityiweyo.Ulwakhiwo lweentambo zeTeflon (FEP) ukusuka kwi-0.69cto0.73c, kanti iintambo ezenziwe ngePVC zikwi-0.60cto0.64crange.
Amaxabiso asezantsi e-NVP aya kuba negalelo ekulibazisekeni okongeziweyo kubude obunikiweyo bentambo, njengokuba ukunyuka kobude bentambo ukuya ekupheleni kuya kubangela ukonyuka okulinganayo ekulibazisekeni ukuya ekupheleni.Njengazo zonke ezinye iiparamitha zothumelo, amaxabiso okulibazisa axhomekeke rhoqo.
Xa izibini ezininzi kwintambo enye zibonisa ukusebenza kokulibaziseka okwahlukileyo, umphumo kukulibaziseka skew.Ukulibazisa i-skew kugqitywa ngokulinganisa umahluko phakathi kwesibini kunye nokulibaziseka okuncinci kunye nesibini esinokulibazisa kakhulu.Izinto ezichaphazela ukulibaziseka kokusebenza kwe-skew ziquka ukukhethwa kwezinto, ezifana nokugquma i-conductor, kunye noyilo lomzimba, njengomahluko kumazinga e-twist ukusuka kwisibini ukuya kwisibini.
Ukulibaziseka koKwandiswa kweCable
Nangona zonke iintambo ezijijekileyo zibonisa ukulibaziseka ukuya kumlinganiselo othile, iintambo eziyilwe ngokunyanisekileyo ukuvumela iiyantlukwano kwi-NVP kunye neperi-to-isibini umahluko wobude ziya kuba nokulibaziseka okwamkelekileyo kulungelelwaniso oluthe tye lwetshaneli.Ezinye zeempawu ezinokuchaphazela kakubi ukulibaziseka kwe-skew ukusebenza zibandakanya iintambo ezinolwakhiwo olungalunganga lwe-dielectric kunye nezo zineeyantlukwano ezigqithileyo kwi-pair-to-pair twist rates.
Ukulibaziseka kosasazo kunye nokulibaziseka kokusebenza kwe-skew kuchazwe yimigangatho yenethiwekhi yendawo yendawo (LAN) yemeko embi kakhulu100 ulungelelwaniso lwe-mchannel ukuqinisekisa ukuhanjiswa komqondiso ofanelekileyo.Iingxaki zothumelo ezayanyaniswa nokulibaziseka okugqithisileyo kunye nokulibaziseka kwe-skew kubandakanya ukwanda kwejitha kunye namazinga empazamo encinci.Ngokusekelwe kwiinkcukacha ze-LAN ze-IEEE 802-series, ukulibaziseka okukhulu kwe-570 ns/100mat 1 MHz kunye nokulibaziseka okukhulu kwe-skew ye-45ns / 100mup ukuya kwi-100 MHz ziphantsi kokuqwalaselwa yi-TIA kudidi lwe-3, i-4 kunye ne-5, i-4-pair cables.IQela eliSebenzayo le-TIA TR41.8.1 likwaqwalasela uphuhliso lweemfuno zokuvavanya ukulibaziseka kokusasazwa kunye nokulibaziseka kwe-skew ye-100 ohm ikhonkco elithe tye kunye nemijelo eyakhiwe ngokuhambelana ne-ANSI/TIA/EIA-568-A.Njengesiphumo sekomiti ye-TIA “iLetter Ballot” TR-41:94-4 (PN-3772) kwagqitywa ngentlanganiso kaSeptemba 1996 ukuba kukhutshwe “Industry Bhalothi” kuyilo oluhlaziyiweyo phambi kokukhululwa.Ayikasonjululwa ngumba wokuba ingaba udidi olutyunjiweyo luya kutshintsha na (umzekelo, udidi 5.1), ukubonakalisa iiyantlukwano phakathi kweentambo ezivavanyelwa ukulibaziseka okongezelelweyo/iimfuno zokulibaziseka kwe-skew, kunye nezo zingekhoyo.
Nangona ukulibaziseka kokusasazwa kunye nokulibaziseka kwe-skew kunikwa ingqwalasela enkulu, kubalulekile ukuqaphela ukuba owona mba ubalulekileyo wokusebenza kweekhebula kwiinkqubo ezininzi ze-LAN uhlala uthintelwa kumlinganiselo we-crosstalk (ACR).Ngelixa imida ye-ACR iphucula umqondiso kwireyishini yengxolo kwaye ngaloo ndlela inciphisa izehlo zeempazamo ezincinci, ukusebenza kwenkqubo akuchatshazelwa ngokuthe ngqo ngamajelo eekheyibhuli anolibaziseko olubalulekileyo lwe-skew margins.Umzekelo, i-15 ns yokulibaziseka i-skew ye-cabling channel ayiyi kubangela nayiphi na intsebenzo yenethiwekhi engcono kune-45 ns, kwinkqubo eyilelwe ukunyamezela ukuya kuthi ga kwi-50 ns ye-skew yokulibaziseka.
Ngesi sizathu, ukusetyenziswa kweentambo ezinolibaziseko olubalulekileyo lwe-skew margins zixabiseke ngakumbi kwi-inshurensi abayinikezelayo ngokuchasene nezenzo zofakelo okanye ezinye izinto ezinokutyhala ukulibaziseka ngaphaya komda, kunokuba kuthenjiswe ukusebenza kwenkqubo engcono xa kuthelekiswa nomjelo onokuthi uqhubele phambili. idibana kuphela nenkqubo yokulibaziseka skew imida ngeenanoseconds ezininzi.
Ngenxa yokuba iintambo ezisebenzisa izinto ezahlukeneyo ze-dielectric kwiibini ezahlukeneyo ziye zafunyanwa ukuba zibangele iingxaki nge-skew yokulibaziseka, kukho ukungqubuzana kwangoku malunga nokusetyenziswa kwezinto ezixubileyo ze-dielectric ekwakheni ikhebula.Amagama afana no “2 ngo 2″ (intambo enezimbini ezimbini ezinemathiriyeli yedielectric “A” kunye neeperi ezimbini ezinemathiriyeli “B”) okanye “4 ngo-0” (intambo enazo zone izibini ezenziwe ngesixhobo esingu-A, okanye imathiriyeli B ) ezicebisa kakhulu ngamaplanga kunentambo, ngamanye amaxesha zisetyenziselwa ukuchaza ukwakhiwa kwedielectric.
Ngaphandle kwe-hype yorhwebo enokulahlekisa umntu ukuba akholelwe ukuba kuphela izakhiwo ezinodidi olunye lwemathiriyeli ye-dielectric eziya kubonisa ukulibaziseka okwamkelekileyo kokusebenza kwe-skew, inyani yeyokuba iintambo eziyilwe ngokufanelekileyo zinesixhobo esinye se-dielectric, okanye izixhobo ezininzi ze-dielectric zikwazi ngokulinganayo ukwanelisa nokuba ezona mfuno zilibaziseko zeshaneli zibukhali ezichazwe yimigangatho yezicelo kunye nezo ziphantsi koqwalaselo yi-TIA.
Phantsi kweemeko ezithile, ulwakhiwo oluxubeneyo lwedielectric lunokude lusetyenziswe ukucombulula ukulibaziseka kweeyantlukwano eziphuma kumazinga ahlukeneyo okujija.Amanani 1 kunye no-2 abonisa ukulibaziseka kommeli kunye ne-skew values efunyenwe kwisampuli yekhebula yeemitha ezili-100 ezikhethiweyo ezino "2 by 2" (FRPE/FEP) ulwakhiwo.Qaphela ukuba ukulibaziseka okukhulu kokusasazwa kunye nokulibaziseka kwe-skew kule sampuli yi-511 ns / 100mand 34 ns, ngokulandelanayo kuluhlu lwamaza ukusuka kwi-1 MHz ukuya kwi-100 MHz.
Ixesha lokuposa: Mar-23-2023