CC LOI CP VIN THNG HIN NAYI. CP NG

I. Cp xon i (Twisted pair)Nm 1881 Alexander Graham Bell l ngi u tin a cp xon i vo s dng trong dch v in thoi.V n nm 1900,loi cp ny c s dng ph bin,rng ri trn ton nc M.Ngy nay hng triu Km cp xon i ang c s dng bn ngoi bi cc cng ty in thoi ,phc v cho truyn ti m thanh.V phn ln cc mng thng tin,Internet cng s dng loi cp ny. Cp xon i(Twisted pair) l loi cp gm nhiu cp dy ng xon li vi nhau nhm chng pht x nhiu in t (Electromagnetic Interference-EMI) t bn ngoi,t s pht x ca loi cp UTP v s xuyn m(Crosstalk) gia nhng cp cp lin k. (Trong thng tin v tuyn, s xuyn m thng c biu th giao thoa ng knh, v lin quan n giao thoa knh- k bn. ) Chng bao lu sau pht minh ra in thoi,cc ng dy cp c s dng trong cng ngh truyn ti .Hai dy c cng ra 2 pha ca thanh cho trn cc cc, truyn ti chung tuyn ng vi dy in.Ban u cc nh nghin cu nhn ra rng dy in lm gim i khong cch truyn ti ca tn hiu in thoi.V mt gii php mi c a ra gi l s chuyn v dy, gim bt s giao thoa,ti cc cc, 2 dy li c vt cho qua nhau.Nh vy mi dy s chu t nh hng ca s pht x nhiu in t t dng in hn.Ngy nay ,nhng ng dy trn vi s chuyn v tun hon nh vy vn c th cn c bt gp cc vng nng thn.iu ny i din cho mt s thi hnh sm ca s xon vi nhp xon l 4 ln trn 1 Km.Da trn nhng thnh qu nghin cu ,nm 1881,Alexander Graham Bell(nh bc hc Thy s ngi pht minh ra chic my in thoi vo nm 1876) a cp xon i vo s dng cho h thng in thoi ca chnh cng ty truyn thng Bell ca ng.

Cp xon c th lm gim nhiu v hai dy ch truyn mt ng d liu, biu din bng hiu in th gia hai dy ny. Khi nhiu nh vo, hai dy xon vo nhau nn s xem nh b nhiu ging nhau, cng tng hoc cng gim mt in p nht nh.Hiu in th gia hai dy vn gi nguyn nn d liu truyn vn ng. Do gi thnh thp nn cp xon c dng rt rng ri c bit l lm cp in thoi v s dng cho cc loi my tnh trong cng ngh truyn thng Internet.Cc loi cp xn i c tc truyn ti a c th ln n hng chc Gigabit/giy (Gbps) vi tn s dao ng c th t ti 600MHz. C hai loi cp xon i c s dng rng ri trong LAN l: loi c v bc chng nhiu(STP) v loi khng c v bc chng nhiu(UTP).

1- Cp xon i khng c v bc chng nhiu UTP(Unshielded Twisted Pair)UTP cp khng c v bc chng nhiu.B li n c tnh linh hot v bn cao.Gm nhiu cp xon nh cp STP nhng khng c lp v ng chng nhiu. Cp xon i trn s dng chun 10BaseT hoc 100BaseT. Do gi thnh r nn nhanh chng tr thnh loi cp mng cc b c u chung nht. di ti a ca mt on cp l 100 mt. Khng c v bc chng nhiu nn d b nhiu khi t gn cc thit b v cp khc do thng thng dng i dy trong nh. u ni dng u RJ-45. Cp UTP c 5 loi:

Loi 1: truyn m thanh, tc