Page 178 - PYTHON-12

Types of Communication/Transmission Media

All communication/transmission media can be divided into two categories:

Communication
Media

Guided Media Unguided Media

Twisted Coaxial Fibre Optic Satellite
Pair Cable Cable Cable Radio waves Microwaves Link

Fig. 8.25: Types of Communication Media

A. Guided Media (Wired Media): Guided media is also known as physical or conducted media.
These media use wires for transmitting data. Various wired connections are twisted pair wire,
coaxial cable and fibre optic cable.

B. Unguided Media (Wireless Media): A transmission media that does not require the use of
cables for transmission of data is known as unguided media. Wireless transmission is also known
as unguided media or non-physical media as the transmission takes place through various types
of electromagnetic waves, such as radio waves, terrestrial microwave transmissions, satellite
transmissions, cellular radio systems, infrared transmissions, etc.

8.12.1 Guided Media or Wired Networking Technologies

1. Twisted Pair Cable

A twisted pair cable is the oldest, simplest and the most
common type of conducted media. It is made of two plastic
insulated copper wires which are twisted together to form
a single wire. Each wire is 1 mm thick. Out of these two
wires, only one carries the actual signal while the other is
used for ground reference. The wires so twisted are helpful Fig. 8.26: Twisted Pair Cable
in avoiding interference from the nearby similar pairs, which
is known as crosstalk. Twisted pair can be specified as Category 1–5 and is abbreviated as Cat 1–5.
Category 6 twisted pair can support data transmission as high as 200 mbps for 100 metres while
Category 7 twisted pair can support still higher data rates.
Computer Science with Python–XII 8.24 (b) Unshielded twisted pair (UTP): UTP has seven categories, each suitable for a specific
Twisted pair comes in two varieties:

(a) Shielded twisted pair (STP): STP cables are covered in metal foil. This makes them
indifferent to noise and crosstalk.

use. In computer networks, mostly Cat-5, Cat-5E and Cat-6 cables are used. UTP cables are
connected by RJ-45 connectors.