2. Transmission media
Signals are transmitted in the form of electromagnetic energy from one
device to another.
OR
Transmission medium is the means through which we send our data
from one place to another
5. Wired or Guided Media or Bound Transmission Media :
Bounded transmission means having connectivity between a source and destination using cables
or wires. The signals have to travel through this channel i.e. physical media and this makes it
limited to its expansion.
6. UnBounded or UnGuided Transmission Media:
• Unguided medium transport electromagnetic waves without using a physical conductor.
• This type of communication is often referred to as wireless communication.
• Signals are normally broadcast through free space and thus are available to anyone who has a device capable of
receiving them.
7. Types of Guided Medium :
Guided Medium
Coaxial Cable Twisted-Pair Cable Fibre-Optic Cable
8. Coaxial Cable:
• Coaxial is called by this name because it contains two conductors that are parallel to each other.
• Copper is used in this as center conductor which can be a solid wire or a standard one.
• Coaxial cables provide high bandwidth rates of up to 450 mbps.
• The actual data travels through the center conductor in the cable
For example TV wire is usually coaxial
Characteristics Of Coaxial Cable:
1.Low Cost
2.Easy to install
3.Medium immunity
4.Medium of attenuation
9. Types of Coaxial Cables:
1. BaseBand:
• It is mostly used for LAN's.
• This is a 50 ohm (Ω) coaxial cable which is used for digital transmission.
• Baseband transmits a single signal at a time with very high speed.
• The major drawback is that it needs amplification after every 1000 feet.
2. BroadBand:
• This uses analog transmission on standard cable television cabling.
• It transmits several simultaneous signal using different frequencies.
• It covers large area when compared with Baseband Coaxial Cable.
10. Advantages of Coaxial Cable:
•Bandwidth is high
•Used in long distance telephone lines.
•Transmits digital signals at a very high rate of 10Mbps.
•Much higher noise immunity
•Data transmission without distortion.
Disadvantages of Coaxial Cable:
•Single cable failure can fail the entire network.
•Difficult to install and expensive when compared with twisted pair.
•If the shield is imperfect, it can lead to grounded loop.
11. Twisted Pair Cable:
• This cable is the most commonly used and is cheaper than
others.
• It is lightweight, cheap, can be installed easily, and they support
many different types of network.
• The purpose of twisting the wires is to reduce electrical
interference (or noice ) from similar pairs close by.
• The most common application of twisted pair is the telephone
system.
• Twisted pairs can run several kilometers without amplification,
but for longer distances repeaters are needed.
Types of Twisted Pair :
Twisted Pair
Unshielded Twisted Pair
(UTP) Cable.
Shielded Twisted Pair
(UTP) Cable.
12. Shielded twisted-pair (STP):
• In Shielded Twisted cable, each pair of insulated conductors
is encased in a metal shield to prevent Crosstalk
• The quality aspect of shielded twisted pair is same as the
Unshielded twisted pair but the shield must be connected to
ground
• It is used for both analog and digital transmission.
• It is said to be a “balanced transmission medium”.
Unshielded twisted Pair(UTP):
• UTP is the most common type of twisted pair cable used in
telecommunication networks.
• The UTP consists of two copper conductors, each having their own
insulating material, intertwined with each other to cancel induced
current.
• The reason for placing twist in the pair of wires is to minimize the
vulnerability of the twisted pair cable to external electrical noise.
• Its frequency range is suitable for data transmission as well as voice
transmission(100Hz-5MHz)
13. 1. Cheaper and far easier to splice
2. In a telephone system, signals can travel several kilometers without amplification when twisted pair wires
are used .
3. It is the least expensive media for transmission for short distances.
4. Because it is electrically "cleaner", STP wire can carry data at a faster speed.
Advantages of Twisted Pair:
Disadvantages of Twisted Pair :
1. STP wire is that it is physically larger and more expensive than twisted pair wire.
2. STP is more difficult to connect to a terminating block.
14. Fiber Optic Cable:
A fibre-optic cable is made of glass or plastic and transmits signals in the form of light.
15. Advantages of Optical Fiber Cable:
• Bandwidth
• Low Power Loss
• Size
• Weight
• Security
• Flexibility
Disadvantages of Optical Fiber Cable:
• Difficult to Splice
• Expensive to Install
• Highly Susceptible
• Can’t Be Curved
17. 1) RADIO WAVE
Radio frequency is easier to generate and because of its large wavelength it can penetrate through walls and
structures a like. Radio waves can have wavelength from 1 mm – 100,000 km and have frequency ranging from 3 Hz
(Extremely Low Frequency) to 300 GHz (Extremely High Frequency). Radio frequencies are sub-divided into six
bands.
Radio wave has frequency between 10 K Hz to 1 G Hz. Radio waves has the following types.
• Short waves
• VHF (Very High Frequency)
• UHF (Ultra High Frequency)
In radio wave there is no security . Example of Radio wave is FM.
18. 2) MICRO WAVE:--
Micro waves travels at high frequency than radio waves and provide through put as a wireless network
media. Micro wave transmission requires the sender to be inside of the receiver.
There are two types of Microwave
a) Terrestrial Micro waves :
Terrestrial Micro waves are used are used to transmit wireless signals across a few miles. These systems
operate in a low Giga Hertz range.
b) Satellite Micro waves :
Satellite micro wave transmission is used to transmit signals throughout the world. Satellite dishes are used
to send the signals to the satellite where it is again send back down to the receiver satellite.
19. 3) INFRARED WAVE
• Infrared signals can be used for short range communication in a closed area using line of sight propagation.
• Infrared wave lies in between visible light spectrum and microwaves.
• The infrared wave are relatively Directional , Cheap and easy to built.
• It has wavelength of 700-nm to 1-mm and frequency ranges from 300-GHz to 430-THz.
Example of Infrared wave is TV remote, DVD remote,
