Wednesday, March 30, 2016

Network media:



Co-axial cable: Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, usually surrounded by a final insulating layer.
It is used as a high-frequency transmission line to carry a high-frequency signal.

Coaxial cables may be rigid or flexible. Rigid types have a solid sheath, while flexible types have a braided sheath, both usually of thin copper wire Thin coaxial: 10base2 is an example of thin coaxial cable
Thick: Example: 10base5


Twisted Pair:  Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of canceling out electromagnetic interference which can cause crosstalk. The greater the number of twists, the more crosstalk is reduced. It can transmit data several kilometers without amplifier. It has high error rate beyond 100m
They are classified into two categories:
1.     UTP ( unshielded twisted pair)
2.     STP (shielded twisted pair)
UTP: UTP cables are not shielded. This lack of shielding results in a high degree of flexibility as well as rugged durability. UTP cables are found in many Ethernet networks and telephone systems.
STP:Twisted pair cables are often shielded to prevent electromagnetic interference. Because the shielding is made of metal, it also serves as a ground STP cabling includes metal shielding over each individual pair of copper wires. This type of shielding prevents cable from external EMI (electromagnetic interferences).

Optical Fiber:  It is based on the  principle of total internal reflelction of light.It is at the one end of optical fiber to accept electrical signal and convert it into light pulses. The presence of pulse indicates a 1 bit  and absence of pulse indicates 0 bits.It contains the following components:

·        Core: It is the innermost part of  fibre made up of glass.
·        Cladding: Glass cladding covers core. Its refractive index is less than core.

·        Jacket:It is an outermost PVC( polyvinoyl chloride) covering of cladding





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