Transmission Media

Transmission Media

The media which are used to transmit and received data in the communication is called transmission media . There are two types of transmission media in the computer network .They are :

a. Guided media

The media which has end to end connection that wires in between the device is called guided media. It is also known as bounded media or wire media. Due to point to point connection in between devices.The data transmission rate is very high as compared to unguided media .Eg: twisted pair cable, coaxial cable & optical fiber.

Some Guided Media

1. Twisted pair cable

a. It is most popular media in communication .

b. It consists of a pair of insulated wires twisted together.

c. It is cheapest and easily available wire which can carry data a large distance without data lost.

Fig. of twisted pair cable

d. The twisted of cables help to reduces noise from outside source and cross talk on multi-pair cable.

e. It is mostly used in telephone system.

f. There are two types twisted pair cable , they are : shielded twisted pair cable and shielded twisted pair cable.

g. The STP simply has additional shielding materials that may be continuous used at any point in paths of cable . It consists higher bandwidth as compare to UTP but it is slide expensive.

h. The UTP cable have not protection against external interference so it preference is also degraded but it is less necessary.

2. Coaxial cable

a. The basic structure is shown in following diagram :

Fig. of coaxial  cable

b. It consists of a thick copper wire in the core surrounded by and insulation plastic with a net of thin copper wires and a thick plastic in the outer part .

c. It is generally come into two categories : Thick coax and thin coax.

d. Thick coax generally has icon core diameter and it has highs degree a noised immunity and 5 band-width ( 100 base 5).

e. It is relatively expensive than twisted pair cable .

f. i t is used in television in our home town( Nepal).

3. Optical fiber

a. It is the most advanced media in communication .

b. It is very thin media is very hard to identify with necked eyes .

Fig: optical fiber

c. It uses light for data transmission rather then critical signal.

d. The basic structure is shown in following diagram:

e. It consists two layer : Glade and core. Both layer at of some materials either plastic or glass . The light is passed through and optical fiber by the process of total internal reflation. It consists "laser" or "LED" as the source to convert electronic signal into light and "PIN" at the receiving end to convert light signal into electronic signal.

f. It does not have any danger of data leakage and electrical interfaces .So, it can be used in any environment such as big factories , grounds or airport etc.

g. It has highest brand width and highest speed as compare to other.

h. Data can travel at long distance without amplification so the amplification cost can be minimized.

i. It is very expensive.

b.Unguided Media

The Media in which are transmitted through some frequently or wave is called unguided media. It is also called bounded  or wireless media. The data transmission speed of such media depends upon various factors such as connecting, distance, etc. Eg: satellite, Bluetooth,WiFi, etc

Some unguided media

 Satellite

It is a space station that receives microwaves signals from and earth based station, amplifies that signals back over of wide range to any number of earth station.

The satellite communication is shown in following diagram:

Fig of communication satellite 

A transmission from the earth to a satellite is called up link and a transmission from satellite to an earth station is called down link.

It is used in various application such as radio and television bread casting , audio and video conferencing etc.