Computer science class XII chapter: NETWORKING

1. TTrraannssmmiissssiioonn MMeeddiiaa ffoorr
NNeettwwoorrkkss
Data transmission is the way or method to transfer any kind of information from oonnee ssppaaccee ttoo aannootthheerr..

2. Communication Channel
 A channel is used to convey an information signal, for example a
digital bit stream, from one or several senders (or transmitters) to
one or several receivers.
 A channel has a certain capacity for transmitting information, often
measured by its bandwidth in Hz or its data rate in bits per second
Data transmission is the way or method to transfer any kind of information from one space to another.

3. Criteria for Media
Evaluation
 Bandwidth –data carrying capacity of a channel
(High bandwidth- broadband, low bandwidth-narrowband)
 Bit rate - expresses the data rate capacity of a networking system
 Delay - The time required to send a signal across a network
 Cost of medium material
 Ease of installation and Maintenance
Data transmission is the way or method to transfer any kind of information from one space to another.

4. Categories of Transmission
Media
A. Guided media
and
B. Unguided Media
Data transmission is the way or method to transfer any kind of information from one space to another.

5. A. Guided Media
 Guided Transmission Media uses a "cabling" system that guides the
data signals along a specific path.
 The data signals are bound by the "cabling" system. Guided Media
is also known as Bound Media.
There 4 basic types of Guided Media:
1. Open Wire
2. Twisted Pair
3. Coaxial Cable
4. Optical Fiber
Data transmission is the way or method to transfer any kind of information from one space to another.

6. Bandwidth comparison
Cable Type Bandwidth
Open Cable 0 - 5 MHz
Twisted Pair 0 - 100 MHz
Coaxial Cable 0 - 600 MHz
Optical Fiber 0 - 1 GHz
Data transmission is the way or method to transfer any kind of information from one space to another.

7. 1. Open Wire
Data transmission is the way or method to transfer any kind of information from one space to another.

8. 2. Twisted Pair
Data transmission is the way or method to transfer any kind of information from one space to another.

9.  Each pair would consist of a wire used for the +ve data signal and a
wire used for the -ve data signal.
 Any noise that appears on 1 wire of the pair would occur on the
other wire. Because the wires are opposite polarities, they are 180
degrees out of phase.
 Numbers of pairs are bundled together. Twisting decreases
crosstalk. When the noise appears on both wires, it cancels or nulls
itself out at the receiving end.
 It is mainly used for telephone system and for subscriber’s loop like
LAN.
 The degree of reduction in noise interference is determined
specifically by the number of turns per foot. Increasing the number
of turns per foot reduces the noise interference.
Data transmission is the way or method to transfer any kind of information from one space to another.

10. Shielded Twisted Pair
Data transmission is the way or method to transfer any kind of information from one space to another.

11. Advantages:
1. Easy to string 2. Cheap
Disadvantages:
 Subject to interference.
 In comparison to others ( Coax & optical fiber) twisted pair is
limited in bandwidth, distance and data rate Like if used for digital
systems it requires repeater after every 2-3 Kms.
 It’s low bandwidth capabilities make it unsuitable for broadband
applications.
 Susceptible to noise weather shielded and unshielded
Data transmission is the way or method to transfer any kind of information from one space to another.

12. UTP and STP cables
Data transmission is the way or method to transfer any kind of information from one space to another.

13. Categories of Twisted-Pair Cables
Category 1: The basic cabling used for voice
Category 2: Suitable for voice and data up to 4 Mbps
Category 3: Suitable for data up to 10 Mbps
Category 4: Suitable for data up to 16 Mbps
Category 5: Suitable for data up to 100 Mbps

14. 3. Coaxial Cable
 Coaxial Cable consists of 2 conductors. The inner conductor is held
inside an insulator with the other conductor woven around it
providing a shield.
 An insulating protective coating called a jacket covers the outer
conductor.
 The outer shield protects the inner conductor from outside electrical
signals.
 The distance between the outer conductor (shield) and inner
conductor plus the type of material used for insulating the inner
conductor determine the cable properties or impedance.
Data transmission is the way or method to transfer any kind of information from one space to another.

15. Coaxial cable is a copper-cored
cable surrounded by a
heavy shielding and is used to
connect computers in a
network. Widely used for
cable TV connections.
Can be used for broadband
transmission.
Outer conductor shields the
inner conductor from picking
up stray signal from the air.
Offers High bandwidth of upto
400MBPS.
Repeater is used to
regenerate the weakened
signals.
Category Impedance Use
RRGG--5599 75 W Cable TV
RRGG--5588 50 W Thin
Ethernet
RRGG--1111 50 W Thick
Ethernet

16. (a.)
Data transmission is the way or method to transfer any kind of information from one space to another.

17. Advantages:
 Not susceptible to interference
 Transmits faster
 With FDM it can carry 10,000 voice channels
Disadvantages:
 Heavy & bulky
 Needs booster over distance. Like repeaters or amplifiers are
needed every few Kms.
Data transmission is the way or method to transfer any kind of information from one space to another.

18. 4. Optical Fiber
 Optical Fiber consists of thin glass fibers that can carry information
at frequencies in the visible light spectrum and beyond.
 The typical optical fiber consists of a very narrow strand of glass
called the Core.
 Around the Core is a concentric layer of glass called the Cladding.
 A typical Core diameter is 62.5 microns (1 micron = 10-6 meters).
Typically Cladding has a diameter of 125 microns.
 Covering the cladding is a protective coating consisting of plastic, it
is called the Jacket.
Data transmission is the way or method to transfer any kind of information from one space to another.

19. Data transmission is the way or method to transfer any kind of information from one space to another.

20. FO Cable may have 1 to
over 1000 fibers

21. Optical fibers use light to send
information through the optical
medium.
It uses the principal of total
internal reflection.
Modulated light transmissions
are used to transmit the
signal.

22. Principle of working
Characteristic of Fiber Optics is Refraction.
The core refracts the light and guides the light along its path.
The cladding reflects any light back into the core and stops light
from escaping through it - it bounds the media!
Data transmission is the way or method to transfer any kind of information from one space to another.

23. Advantages:
 Noise immunity: RFI and EMI immune (RFI - Radio Frequency
Interference, EMI –Electro Magnetic Interference)
 Security: cannot tap into cable. Hence guarantees secure
transmission.
 Large Capacity due to BW (bandwidth) , can handle several
channels in parallel.
 No corrosion
 Longer distances than copper wire
 Smaller and lighter than copper wire
 Faster transmission rate
 Highly suitable for harsh industrial environments.
Data transmission is the way or method to transfer any kind of information from one space to another.

24. Disadvantages :
 Physical vibration will show up as signal noise.
 Limited physical arc of cable. Bend it too much & it will break.
 Difficult to split, Highly fragile.
Copper:
 It has low resistance to electrical current and signal travels farther.
 guided medium
 bandwidth - depends on the thickness of the wire and the distance
traveled.
 interference - susceptible to electromagnetic waves generated by
neighboring wires.
 Two main types - twisted pair and coaxial cable (coax)
Data transmission is the way or method to transfer any kind of information from one space to another.

25. The Advantages of Fiber over Copper :
 Interference - does not cause interference; and is not susceptible
to interference.
 Bandwidth - handles much higher bandwidth than copper
 Low attenuation - requires fewer repeaters and amplifiers (every
30 Km vs. 5Km)
 Immune to power surges, failures, and other electromagnetic
interference
 thin and lightweight
 don’t leak light; tough to tap (secure)
Data transmission is the way or method to transfer any kind of information from one space to another.

26. B. Unguided Media
 Unguided media ttrraannssppoorrtt eelleeccttrroommaaggnneettiicc wwaavveess
wwiitthhoouutt uussiinngg aa pphhyyssiiccaall ccoonndduuccttoorr.. TThhiiss ttyyppee ooff
ccoommmmuunniiccaattiioonn iiss oofftteenn rreeffeerrrreedd ttoo aass wwiirreelleessss
ccoommmmuunniiccaattiioonn..
Radio Waves
Microwaves
Infrared
Data transmission is the way or method to transfer any kind of information from one space to another.

27. Wireless transmission waves

28. Also called wireless communication. It transports electromagnetic
Waves without using a physical conductor. Signals are broadcast
through the air ( in some cases water). There are available to
anyone who can receive them.
Radio Frequency Allocation – the selection of the electromagnetic
spectrum defined as radio communication is divided into 8 ranges,
called bands, each regulated by government. These bands are
rated from very low frequency (VLF) to very high frequency (EHF)
VLF and HF – this propagate very close to the surface.
MF and HF – upper layers and then reflect back to the earth
VHF and UHF – transmitted using line of sight –
EHF and SHF – space propagation.

29. Frequency Bands
BBaanndd RRaannggee PPrrooppaaggaattiioo
nn AApppplliiccaattiioonn
VVLLFF 3–30 KHz Ground Long-range radio navigation
LLFF 30–300 KHz Ground Radio beacons and
navigational locators
MMFF 300 KHz–3 MHz Sky AM radio
HHFF 3–30 MHz Sky Citizens band (CB),
ship/aircraft communication
VVHHFF 30–300 MHz Sky and
line-of-sight
VHF TV,
FM radio
UUHHFF 300 MHz–3 GHz Line-of-sight
UHF TV, cellular phones,
paging, satellite
SSHHFF 3–30 GHz Line-of-sight
Satellite communication
EEHHFF 30–300 GHz Line-of-sight
Long-range radio navigation

30. Propagation methods
Data transmission is the way or method to transfer any kind of information from one space to another.

31. Radio Waves
•Radio waves are used for multicast communications, such
as radio and television, and paging systems.
• They can penetrate through walls.
•Highly regulated.
•Use omni directional antennas

32. Omnidirectional antenna

33. Micro Waves
•Microwaves are used for unicast communication such as cellular
telephones, satellite networks,and wireless LANs.
•Higher frequency ranges cannot penetrate walls.
•Use directional antennas - point to point line of sight
communications
Data transmission is the way or method to transfer any kind of information from one space to another.

34. Unidirectional antennas

35. Terrestrial Microwave
Microwaves do not follow the
curvature of earth
Line-of-Sight transmission
Height allows the signal to
travel farther
Two frequencies for two way
communication
Repeater is used to increase
the distance Hop-by-Hop

36. Satellite Communication

37. Infrared Waves
Infrared signals can be used for short-range
communication in a closed area using line-of-sight
propagation.
Used in TV remotes.
Will not penetrate walls.
Data transmission is the way or method to transfer any kind of information from one space to another.

38. Laser
Transmission
Used for line of sight transmission.
Faster than microwaves.
Adversely affected by weather.
Data transmission is the way or method to transfer any kind of information from one space to another.

39. Wireless Media
Very useful in difficult
terrain where cable
laying is not possible.
Provides mobility to
communication nodes.
Right of way and cable
laying costs can be
reduced.
Susceptible to rain,
atmospheric variations
and Objects in
transmission path.
Are subject to a lot more
errors than guided media
channels..

40. Wireless Media
Indoor : 10 – 50m : BlueTooth, WLAN
Short range Outdoor : 50 – 200m: WLAN
Mid Range Outdoor : 200m – 5 Km : GSM, CDMA, WLAN
Point-to-Point, Wi-Max
Long Range Outdoor : 5 Km – 100 Km : Microwave
Point-to-Point
Long Distance Communication : Across Continents :
Satellite Communication