Guided/Wired Transmission Media in Computer Network

  • Post last modified:13 December 2020
  • Reading time:11 mins read
  • Post category:Computer Network
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Guided Media

Guided Media is also known as Wired or Bounded transmission media. A signal travelling the media is directed and confined by the physical limits of the medium.

Advantage of guided media

  • More secure
  • Provides high speed
  • Used for shorter distances

Disadvantage of guided media

  • Need Physical link
  • Time Consuming

Read: Introduction To Computer Network

Three Types of Guided Media

There are three types of guided media which are Twisted-Pair Cable, Coaxial Cable and Fiber-Optic Cable are explained below.

Twisted-Pair Cable

Twisted-Pair Cable consists of two insulated conductors wire wound (normally copper), twisted together. In which one wire is to carry the signal to destination and other is used as a ground reference. Twisting is done so that the noise will equally affect the wire from the external environment.

Advantage of Twisted Pair Cable

  1. The frequency range is 0 to 3.5 kHz
  2. Repeater spacing is 2 KM

Disadvantage of Twisted Pair Cable

  1. No capacity to carrying a signal over long distances without the use of repeaters.
  2. Not suitable for broadband applications because of low bandwidth capacity.
  3. Poor security and easy to tap.

Applications of Twisted Pair Cables

  1. It is used in telephone lines.
  2. Also used in the DSL line (ADSL)
  3. ISDN (Integrated Services Digital Network).

Read: Types of Network Topology

Types of twisted pair cable

Unshielded Twisted-Pair Cable

Unshielded Twisted-Pair Cable is the widely used twisted-pair cable used in telecommunications as Ethernet cables and telephone wires.

UTP cables consist of 2  pairs of twisted cable use RJ-11 connector and cables consist of 4  pairs use an RJ-45 connector.

Advantages of Unshielded Twisted-Pair Cable
  1. Higher data rates
  2. Easy to set up and install
  3. Flexible and low-cost media
Disadvantages of Unshielded Twisted-Pair Cable
  1. Limited bandwidth
  2. Susceptible to noise and cross talk

Shielded Twisted-Pair Cable

This type of cable consists of a special braided metal foil to block external interference.

Advantages of Shielded Twisted-Pair Cable
  1. Better performance at a higher data rate
  2. Eliminates cross talk
  3. Comparatively faster
Disadvantages of Shielded Twisted-Pair Cable
  1. Difficult to manufacture and install
  2. Bulky and expensive
  • It is used in telephone lines to provide data and voice channels.

Read: Line Configuration in Computer Networks

Coaxial Cable

Coaxial cable has a central core conductor of stranded or solid wire (usually copper) enclosed in an insulating protection cover, which is, in turn, encased in an outer conductor of metal foil or a combination of the two. The outer metallic work as a shield against noise and as a conductor, which complete the circuit. The whole cable is covered by a plastic cover.

Two types of Coaxial Cable

  1. BaseBand: (50 ohms) used for digital transmission.
  2. BroadBand: uses for analog transmission on standard TV cable.

Coaxial cable advantages

  1. Carries signals of higher data rate and bandwidth.
  2. Used in analog telephone networks and traditional Cable TV networks.

Coaxial cable disadvantages

  1. The network depends on a single cable.
  2. Expensive and difficult to install when compared with twisted pair.

Applications of Coaxial cable

  • Used in analog telephone networks, could carry 10,000 voice signals.

Fiber-Optic Cable

Fiber-Optic Cable is made of glass and transmits of data is based on the concept of reflection of light through glass. A glass core is surrounded by less dense glass called cladding.

Two types of Propagation Modes

Multimode mode

Multiple light beams from a light source move through the core in different paths.

It is implemented in two forms: step-index and graded-index.
(a) Step-index: density of the core remains constant from the centre to the edges.
(b) Graded-index: decreases this distortion of the signal through the cable

Single mode

Single-mode uses step-index fiber and a focused source of light which limits beams to a small range of angles, all close to the horizontal.

Reference: guided/wired transmission media (Wikipedia)

Read: Transmission Modes in Computer Networks

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