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2. WHAT IS COMMUNICATION?
Communication is the process of
exchanging information between two
different points.
The information may be sent from one
point to another point through a wire /
cable or it may be sent on particular
frequency (wireless) on air.

3. COMMUNICATION REQUIREMENTS

4. BLOCK DIAGRAM OF COMMUNICATION
SYSTEM
Input
Transducer
Modulator
Demodulator
Amplifier
Receiver Amplifier
Output
Transducer
Transmitter
Input
information
Output
information

5. INPUT TRANSDUCER
Input Transducer:
• A transducer is a sensor that changes energy from one form to another.
More technically a transducer converts a physical parameter into another
form.
• Transducers can be used at the input (a microphone) or the output (a
speaker) of a system.
• With electronic-measuring systems, the input transducer converts a
quantity to be measured (temperature, humidity, flow rate, weight) into an
electrical parameter (voltage, current, resistance, capacitance) that can be
processed by an electronic instrument or system.

6. INPUT TRANSDUCER
Transducers are used in electronic communications systems to convert
signals of various physical forms to electronic signals, and vice versa. In this
example, the first transducer could be a microphone, and the second
transducer could be a speaker.

7. TRANSMITTER
• It is the one which transmits the information after processing
the normal signal (modulating signal) to modulated signal.
• It has some elements like modulator to combine low
frequency information with RF carrier and an amplifier to
amplify the signal before giving it to the antenna.
Receiver
• It is the one, which receives the modulated information and
retrieves the actual information from the modulated signal.
• It has an amplifier to amplify the weak signal and a
demodulator to separate the actual information from the
modulated information.

8. CHANNEL
• It is the medium through which the information is being
carried out.
• If the information is being carried over wires, it is called wire
line communication.
• If the information is carried over a particular frequency on air,
it is called wire less communication.

9. MODULATOR & DEMODULATOR
• Modulator: A radio frequency modulator (or RF modulator) takes a
baseband input signal and then outputs a radio frequency modulated
signal. This is often a preliminary step in signal transmission, either by
antenna or to another device such as a television.
• Demodulator: A demodulator is a circuit that is used in amplitude
modulation and frequency modulation receivers in order to separate the
information that was modulated onto the carrier from the carrier itself. A
demodulator is the analog part of the modulator. A modulator puts the
information onto a carrier wave at the transmitter end and then a
demodulator pulls it so it can be processed and used on the receiver end

10. AMPLIFIER
• An electronic amplifier, or (informally) amp is an electronic device that
increase the power of a signal.
• It does this by taking energy from a power supply and controlling the
output to match the input signal shape but with a larger amplitude.
• In this sense, an amplifier modulates the output of the power supply to
make the output signal stronger than the input signal.
The four basic types of amplifiers are as follows:
• Voltage amplifier
• Current amplifier

11. WIRED VS. WIRELESS
• The main difference between the wired and wireless
communication infrastructure is the existence of the physical
cabling.
• Wired communication consists of a physical cable between
two points, where as wireless communication doesn’t have
any physical cabling between the points. The information will
be sent on a particular frequency over air.

12. WIRED VS. WIRELESS

13. TRANSMITTER AND RECEIVER
Transmitter
A radio transmitter consists of several elements that work together to
generate radio waves that contain useful information such as audio, video, or
digital data.

14. TRANSMITTER
• Power supply: Provides the necessary electrical power to operate the
transmitter.
• Oscillator: Creates alternating current at the frequency on which the
transmitter will transmit. The oscillator usually generates a sine wave,
which is referred to as a carrier wave.
• Modulator: Adds useful information to the carrier wave. There are two
main ways to add this information. The first, called amplitude modulation
or AM, makes slight increases or decreases to the intensity of the carrier
wave. The second, called frequency modulation or FM, makes slight
increases or decreases the frequency of the carrier wave.
• Amplifier: Amplifies the modulated carrier wave to increase its power. The
more powerful the amplifier, the more powerful the broadcast.
• Antenna: Converts the amplified signal to radio waves.

15. RECEIVER
• A radio receiver is the opposite of a radio transmitter. It uses an antenna to
capture radio waves, processes those waves to extract only those waves
that are vibrating at the desired frequency, extracts the audio signals that
were added to those waves, amplifies the audio signals, and finally plays
them on a speaker.

16. RECEIVER CONT..
• Antenna: Captures the radio waves. Typically, the antenna is simply a
length of wire. When this wire is exposed to radio waves, the waves
induce a very small alternating current in the antenna.
• RF amplifier: A sensitive amplifier that amplifies the very weak radio
frequency (RF) signal from the antenna so that the signal can be
processed by the tuner.
• Tuner- A circuit that can extract signals of a particular frequency from a
mix of signals of different frequencies. On its own, the antenna captures
radio waves of all frequencies and sends them to the RF amplifier, which
dutifully amplifies them all.
Unless you want to listen to every radio channel at the same time, you
need a circuit that can pick out just the signals for the channel you want to
hear. That’s the role of the tuner

17. RECEIVER CONT..
• Detector: Responsible for separating the audio information from the
carrier wave. For AM signals, this can be done with a diode that just
rectifies the alternating current signal. What’s left after the diode has its
way with the alternating current signal is a direct current signal that can be
fed to an audio amplifier circuit. For FM signals, the detector circuit is a
little more complicated.
• Audio amplifier: This component's job is to amplify the weak signal that
comes from the detector so that it can be heard. This can be done using a
simple transistor amplifier circuit.
• Of course, there are many variations on this basic radio receiver design.
Many receivers include additional filtering and tuning circuits to better
lock on to the intended frequency — or to produce better-quality audio
output — and exclude other signals. Still, these basic elements are found
in most receiver circuits.

18. TYPES OF WIRELESS COMMUNICATION
• Point-to–Multipoint
• Broadcasting
• Simplex System
• Half Duplex System
• Full Duplex System

19. TYPES OF COMMUNICATION SYSTEMS
• Point-to–multipoint communication: In this type of
communication, there is one sender and multiple recipients.
For example in video conferencing one person will be talking
but many others can listen. The message from the sender has
to be multicast to many others.
• Broadcasting: In broadcasting, there is central location from which
information is sent to many recipients as in the case of audio or video
broadcasting. In a broadcasting system, the listeners are passive and there
is no reverse communication path.

20. SIMPLEX SYSTEM
• It is one way communication. It can either transmit
or receive. But only one function it does at any time.
– Ex: Radio, Television, GPS Rx etc.

21. HALF DUPLEX
It can do both the functions. i.e., it can transmit as well as receive. But
only one function at a time. That means, if it is transmitting, it works
like a transmitter and if it is receiving, it works like a receiver.
Ex: Police Walkie-Talkie

22. FULL DUPLEX
It can do both the (Tx and Rx) functions at a time.
Ex: Telephone and mobile systems

23. CURRENT WIRELESS SYSTEM
• Cellular systems
• Wireless LANs
• Satellite Systems
• Infrared Communication
• Broadcast Radio
• Mobile communication
• Bluetooth
• Wi-fi

24. WIRELESS COMMUNICATION
Advantages:
 Mobility
 A wireless communication network is a solution in areas where cables are
impossible to install (e.g. hazardous areas, long distances etc.)
 Easier to maintain
Disadvantages:
 Has security vulnerabilities
 High costs for setting the infrastructure
 Unlike wired communication wireless comm. is influenced by physical
obstructions, climatic conditions, interference from other wireless
devices

25. MODULATION
In electronics and telecommunications, modulation is the process of
varying one or more properties of a periodic waveform, called the carrier
signal, with a modulating signal that typically contains information to be
transmitted.

26. 59
MODULATION
• It is the process of superimposing the modulating signal over a high freq.
Carrier.
• Modulation = Adding information (e.g. voice) to a carrier electromagnetic
(radio) signal

27. 61
NEED OF MODULATION
• To reduce the noise and interference (More discussion about
interference)
• Multiplexing and de multiplexing (More discussion about MUX and
DEMUX Later)
• Todecrease the Antenna size ( Antenna Discuss later)
• Totransmit the audio signal to far distance

28. 63
TYPES OF MODULATION
Different types of Analog modulations are
• Amplitude modulation.
• Frequency modulation.
• Phase modulation
Amplitude modulation:
• If the Amplitude of the carrier signal is varied according to the amplitude
of the modulating signal, it is called Amplitude Modulation
• AM was the earliest modulation method used to transmit voice by radio

29. 64
AMPLITUDE
MODULATION

30. AMPLITUDE MODULATION
Advantages:
• It is simple to implement
• It can be demodulated using a circuit consisting of very few components
• AM receivers are very cheap as no specialized components are needed
Disadvantages
• It is not efficient in terms of its power usage.
• It is prone to high levels of noise because most noise is amplitude based
and obviously AM detectors are sensitive to it

31. 66
FREQUENCY MODULATION
Frequency Modulation:
• If the Frequency of the carrier signal is varied according to the Amplitude
of the modulating signal, it is called Frequency modulation
• Frequency modulation (FM) is most commonly used for
radio,Radar,Music,Speech and television broadcast. The FM band is
divided between a variety of purposes.
• In addition, the FM band also includes FM radio, which operates from 88
MHz to 108 MHz. Each radio station utilizes a 38 kHz frequency band to
broadcast audio. Above 108Mhz reserved for navigation signals used by
aircraft to find runways so broadcasting on this range is not allowed(also
most radios 99% won’t tune this high) while below 87.6 some countries
below 65.8MHz used by other service like television ,two way radios and
emergency service

32. 67
FREQUENCY MODULATION

33. ADVANTAGES
 Less noise: The modulation is carried only as variations in frequency. This
means that any signal level variations will not affect the audio output,
provided that the signal does not fall to a level where the receiver cannot cope.
• Easy to apply modulation at a low power stage of the transmitter: It is
possible to apply the modulation to a low power stage of the transmitter,
and it is not necessary to use a linear form of amplification to increase the
power level of the signal to its final value.
Disadvantages
• More complicated receiver and transmitter

34. MULTIPLEX &
DEMULTIPLEX
• In Telecommunications and computer networks, multiplexing
(sometimes contracted to muxing) is a method by which multiple
analog or digital signals are combined into one signal over a
shared medium. For example, in telecommunications, several
telephone calls may be carried using one wire.
• The multiplexed signal is transmitted over a communication
channel, such as a cable. The multiplexing divides the capacity of
the communication channel into several logical channels, one for
each message signal or data stream to be transferred.
• A reverse process, known as Demultiplexing, extracts the original
channels on the receiver end. A device that performs the
multiplexing is called a multiplexer (MUX), and a device that
performs the reverse process is called a demultiplexer (DEMUX or
DMX).
• Inverse multiplexing (IMUX) has the opposite aim as multiplexing,
namely to break one data stream into several streams, transfer
them simultaneously over several communication channels, and
recreate the original data stream.

35. MULTIPLEXING

36. 1. FDM( Frequency division Multiplexing)
2. WDM(Wave Length division Multiplexing)
3. TDM(Time division Multiplexing): TDM divided in two parts---
a) Synchronous TDM
b) Asynchronous TDM
Frequency Division Multiplexing (FDM)
• FDM was developed to work with early telephone networks. It worked by
dividing the frequencies to support multiple users. In FDM , the signals are
translated into different frequency bands and sent over the medium. The
communication channel is divided into different frequency bands, and
each band carries the signal corresponding to one source
TYPES OF
MULTIPLEXING:

37. FREQUENCY DIVISION MULTIPLEXING (FDM)
In FDM- f1,f2,f3………..( Different Freq.)
But Time constant=T (At the same time)
In FDM, Signals of different frequencies are combined into a
single composite signal & is transmitted on single link

38. APPLICATION OF FDM:
• One of FDM’s most common application is cable television. Only one cable
reaches a customer’s home the service provider can send multiple
television channels or signal simultaneously over that cable to all subscriber
with interference.Recievers must tune to the appropriate freq. to access the
desired signal
• FDM is used for FM & AM radio broadcasting
• FDM is used in television broadcasting
• First generation cellular telephone also uses FDM
Time Division Multiplexing (TDM)
• TDM was developed later (late 1950's) with new "digital" technology. This
works a little different than FDM, in that users are given all of the
frequency some of the time. The way TDM actually works is pretty
complicated.
• However, the process involves converting signals from analog to digital.
TDM not only allows more data to be sent over a physical medium, it
provides a better quality of service (Quos).

39. TIME DIVISION MULTIPLEXING
(TDM)
TDM comes in two
flavors:
i) SynchronousTDM
ii) AsynchronousTDM

40. © UTL Technologies www.utltraining.com
MULTIPLE ACCESS METHOD
Multiple Access means that all devices have equal access to the
network
It determines how several users can share a medium with minimum or
no interference
FDMA (Frequency Division Multiple Access)
TDMA (Time Division Multiple Access)
CDMA (Code Division Multiple Access)

41. © UTL Technologies www.utltraining.com
FDMA
FDMA is a method that lets more than one user to share a single radio
frequency spectrum. This is done by assigning active users a different
frequency channel. FDMA is a basic technology in the Analog Advanced
Mobile Phone Service (AMPS), the most widely-installed cellular phone
system installed in North America. T is same ,f varies

42. © UTL Technologies www.utltraining.com
TDMA
Time division multiple access (TDMA) :
In TDMA ,The channels(freq.) is not divided on the basis of freq. but on the
basis of time. Total time available in the channel is divided between
several users.
Each time is allotted a particular a time interval called time slot during
which the data is transmitted by the user.
E.g- Playing Card
T1,T2,T3,T4.........(Time different)
f1= Frequency(Same)

44. CDMA

45. TRANSMISSION MEDIA/MEDIUM
The Media through, which transmission takes place is called as Transmission
Media. There are two types of transmission media. They are
 Guided or Wired Media
 Unguided or Wireless Media
GUIDED MEDIA: With guided transmission media ,the waves are guided
along a physical path. E.g.- twisted pair cables, Co-axial & Fiber optic
cable
UNGUIDED MEDIA: With unguided transmission media, the waves /data
are not guided by any physical path.
E.g.- Microwave ,Radio or Infrared

46. TRANSMISSION MEDIA
Transmission
media
Guided
(wired)
Twistedpair Coax Optical fiber
Unguided
(wireless)
Satellite
Microwave
LOS

47. TWISTED PAIR
• Twisted pair is the ordinary copper wire that connects home and many
business computers to the telephone company.
There are two types of twisted pair
cables. They are,
•Unshielded Twisted Pair
(UTP)
•Shielded Twisted Pair (STP)

48. • Unshielded twisted pair (UTP) is the most popular and is generally the
best option. UTP cable is popular cable which is used in computer
networking that consist of two shielded wires twisted around each
other.

49. UTP(UNSHIELDED TWISTED
PAIR)
used by phone
supporting computer network traffic. It is also companies who
provide ISDN.
– CAT2 :supporting speeds up to 4 Mbps.
– CAT 3 (Category 3): up to 10 Mbps of data
– CAT 4 (Category 4): 16 Mbps throughput
– CAT 5 (Category 5): up to 100 Mbps throughput
– CAT 6 (Category 6): six times the throughput of CAT 5
– CAT 7 (Category 7): signal rates up to 1 GHz
 Connectors:
i) RJ 45 & RJ 11 -

50. UNSHIELDED TWISTED PAIR
CONNECTOR
• The standard connector for unshielded twisted pair
cabling is an RJ-45 connector. This is a plastic
connector that looks like a large telephone-style
connector .
• A slot allows the RJ-45 to be inserted only one way. RJ
stands for Registered Jack, implying that the
connector follows a standard borrowed from the
telephone industry. This standard designates which
wire goes with each pin inside the connector
Shielded Twisted Pair Cable
Twisted pair is
enclosed in a shield
that functions as a
ground. This is known
as shielded twisted
pair (STP)

51. i) Mostly used for LAN( Local Area Network)
ii) They can be used for voice, low speed data, high speed data, audio
etc..
• Categories:
– CAT1 is typically telephone wire. This type of wire is not
capable of

52. STP
• A disadvantage of UTP is that it may be
susceptible to radio and electrical
frequency interference.
• Shielded twisted pair (STP) is suitable for
environments with electrical interference;
however, the extra shielding can make the
cables quite bulky.
Comparing STP and UTP
Throughput: STP and UTP can both
transmit data at 10, 100, and 1000
Mbps Depending on grade of cabling
and transmission method used
Cost: STP usually more expensive than
UTP
Connector: Both use RJ-45 and RJ-11
Noise Immunity: STP more noise-
resistant
Size and scalability: Max segment
length for both is 100 m on 10BASE-T
and 100BASE-T networks
Maximum of 1024 nodes

53. COAXIAL CABLE
Coaxial cables are widely employed
today to carry signals between
various electronic devices such as
televisions, displays, computers,
CRT displays, transceivers,
computer stations on a computer
network, etc.
The coaxial cables commonly used
today for transmission of RF signals
comprise a core containing an inner
conductor, a metallic sheath
surrounding the core and serving as
an outer conductor, with a
protective jacket surrounding the
metallic sheath. The inner electrical
conductor is completely encircled
by an outer electrical conductor
with a non-conducting layer
between them.

54. COAXIAL CABLE CONNECTORS
• The most common type of connector used with
coaxial cables is the Bayone-Neil-Concel-man
(BNC) connector . Different types of adapters are
available for BNC connectors, including a T-
connector, barrel connector, and terminator.
• C110-F
Coaxial F RG6 Crimp Connectors F
crimp connector for RG6 dual- and
quad-shield coaxial cable
• SNS - Snap-N-Seal Compression
Connectors.

55. Fiber Optics
• Fiber optics (optical fibers) are long, thin strands of very pure glass about
the diameter of a human hair.

56. ELEMENTS OF
FIBER:
Core
• Thin glass center of the fiber where
the light travels
Cladding
• Outer optical material surrounding
the core that reflects the light back
into the core
Buffer coating
• Plastic coating that protects the fiber
from damage and moisture
• Hundreds or thousands of these
optical fibers are arranged in
bundles in optical cables. The
bundles are protected by the cable's
outer covering, called a jacket.
Types of Fiber

57. ADVANTAGES ---OPTICAL FIBER ---
DISADVANTAGES
• Low Signal Loss in Fiber Optics. Long
Distance Transmission 60km to 300 km.
• Due to low attenuation, repeaters are
needed about every 60kms compared to
every 5kms for copper, reducing cost.
Maintenance is very high for conventional
medium. High Band width. Conventional
medium supports 500 MHz to 700 MHz.
Fiber Optics supports several GHz.
• Since it uses light, it is not affected by power
surges, EM interference or power failures.
Also not affected by corrosive chemicals in
the air. Fiber is small in size (thin) and less in
weight.
• Fiber optic cable is more
expensive. Needs skilled job
for cable joints by splicing.
• Sophisticated equipment is
required.

58. FIBER
OPTICS
Splicing:
• Splicing is a method of joining two
properly aligned fibers that the two fibers
are held together and the transmission of
light continues.
• Fusion splicing is the act of joining two
optical fibers end-to-end using heat. The
goal is to fuse the two fibers together in
such a way that light passing through the
fibers is not scattered or reflected back by
the splice, and so that the splice and the
region surrounding it are almost as strong
as the virgin fiber itself.
• The source of heat is usually an electric
arc but can also be a laser, or a gas flame,
or a tungsten filament through which
current is passed.

59. Process of fusion Splicing:
• The process of fusion splicing
normally involves using localized heat
to melt or fuse the ends of two
optical fibers together. The splicing
process begins by preparing each
fiber end for fusion.
i) Stripping the fiber
ii) Cleaning the fiber
iii) Cleaving the fiber
iv) Splicing the fibers
OTDR:
• OTDR Stands for Optical time domain
reflectometer. The aim of OTDR is to
Test,detcet,locate & measure events at
any location in the fiber optic link

60. UNGUIDED
TRANSMISSION
In this communication Antenna play a main Role, It is
also called wireless communication. It transports
electromagnetic waves without using a physical
conductor. Signals are broadcast through the Air.
Basically there are two types of configuration happens
in wireless communication:
i) Point to Point Communication
ii) Broadcast communication

61. UNGUIDED TRANSMISSION
• The term "RF waves" typically refers to radio frequency waves, a form
of electromagnetic energy invisible to the human eye. Radio
frequency communication is virtually omnipresent in the modern
world, used for everything from automobile radios to computers.
• Radio frequency (RF) is a rate of oscillation in the range of about 3
kHz to 300 GHz, which corresponds to the frequency of radio waves.

62. UNGUIDED TRANSMISSION
• This consists of means of data signals to travel
but nothing to
guide them along a specific path.
• The data signals are not bound to a cabling
media and as such are often called unbound
media.
• Unguided transmission
– Line of sight communication
– Satellite communication

63. LINE OF SIGHT COMMUNICATION
• It achieves line of sight transmission to receiving antenna.
• Line of sight propagation transmits exactly in the line of sight.
• The receive station must be in the view of the transmit station.
• It is sometimes called space waves or Troposphere
propagation.

64. LOS(LINE OF SIGHT)

65. LOS(LINE OF
SIGHT)
LOS Tools:
 Compass
 Maps
 Digital camera
 GPS
 Binocular
 Signaling mirror
 Measuring tape

66. FRESNEL ZONE
• Zone surrounding the RF LOS is said to be the Fresnel zone
• To maximize receiver strength, one needs to minimize the effect of
the out-of-phase signals by removing obstacles from the radio
frequency line of sight(RF LOS). The strongest signals are on the
direct line between transmitter and receiver and always lie in the
first Fresnel zone
• If unobstructed, radio waves will travel in a straight line from the
transmitter to the receiver. But if there are obstacles near the path,
the radio waves reflecting off those objects may arrive out of phase.
The signals that travel directly and reduce the power of the received
signal.

67. NOISE
• In communications, interference that destroys the integrity of signals on a
line.
• Noise can come from a variety of sources, including radio waves, nearby
electrical wires, lightening, and bad connections.

68. Thanks!!