twisted pair cables

7/28/2019 Twisted Pair Cables

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A twisted pair cabling is a type of wiring were twoconductors are twisted together in order to cancel outelectromagnetic interference from external source.

Twisted pair cable is used in guided media to provide a

conduit(Channel or a pipe conveying liquids ) from onedevice to another.

A twisted pair consists of two conductor(Normally copper), each with its own plastic insulation(which is used

only as ground reference).Twisted pair cable were invented by Alexander Graham Bellin 1881.



Twists- It is extremely important that each pair is twistedtogether for the duration of the cable length. At lowfrequencies this is not a problem, but at high frequencies,noise and crosstalk became a major problem.

Crosstalk- When wires are lade side by side, actual data

travelling through them causes tiny external electromagnetic signals, that work the way into the adjacent wire.this is called cross talk.

These unwanted frequencies have an equal effect on both

wires in same direction (polarity).It was found that by twisting the wires together ,the electro-magnetic polarity of the unwanted signals is skewed as the wire bends andtwists this has an cancelling effect .The more twists per

inch of wire the better the cancellation effect.



I. Unshielded Twisted Pair Wire.II. Shielded Twisted Pair.

Unshielded Twisted Pair Wire :UTP is what’s typically installed by phone companies and is

what 10base T Ethernet runs over UTP is graded.UTP is graded according to its data carrying ability (e.g.,

Level 3,Level 4,Level 5).

Shielded Twisted pair wire.STP is typically used for Token-ring networks where it iscommonly referred to IBN type 2.(Or 2,3,6,8,etc)

However there are several manufacturers of Ethernetequipment and interfaces that support Ethernet over STP.



Category Specification DataRate(Mbps)

Use

1 Unshielded twisted pair used in telephone <0.1 Telephone

2. UTP wires originally used in t-lines 2 T-lines

3. Improved CAT 2 used in LANS 10 LANs

4. Improved CAT 3 used in token ring network 20 LANs

5.

5E.

Cable wire is normally 24AWG with jacket & outsidesheath . An extension to category five that includes extra

features to minimize the crosstalk &electromagnetic interference

100

125

LANs

LANs

6. To test the new category with matched componentfrom same manufacturer

200 LANs

7. SST(Shielded screen twisted pair) the shielddecreases the effect of cross talk & increases the

600 LANs



I. These are cheaper and far easier tosplice.

II. Less susceptible to electricalinterference caused by nearby equipmentor wires.

III. In turn are less likely to causeinterference themselves.

IV. Because it electrically “cleaner” ,STP

wire can carry data at a faster speed.



I. STP wire is that it is physically larger and moreexpensive than twisted pair wires.

II. STP is more difficult to connect to a terminatingblock.

twisted pair cables

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