Basics of Communication
Nithin Kumar N.R
HOD
Dept of EEE
Sanjay Memorial Polytechnic
Curriculum
References
Importance of Electronic Communication
• Long distance communication is not possible without
electronic media.
• More and more people are looking for electronic means to
transmit information.
• Well-known forms of electronic communications, such as the
telephone, radio and television, have increased our ability to
share information. Today they are major part of the our lives.
• An unexpected development in the role that computers play
in communication E-mail and Internet allows:
• Most economical way to get informations and
communication.
• Very high speed.
• High security because of individual log-in and passwords.
• On-line shopping, booking.
Communication systems
system
carrier
signal carried as
hilltop beacons
light
on-off (fire or no fire)
telegraph
electric current
on-off (Morse code)
cable TV
infrared in optical fibres
ultra-fast (on-off) pulses
mob phone
microwave
ultra-fast (on-off) pulses
AM radio
radio wave
changing amplitude (AM)
FM radio
radio wave
changing frequency (FM)
Comms technologies change
Communications: key terms
transmitter ……………........… receiver
encoding …………………….. decoding
modulation…………….... demodulation
All communication systems must contend with noise – unwanted
interference. Engineers consider signal-to-noise ratio.
Other parameters: data transmission rate, range, signal encoding.
Source–journey–detector
A useful model when describing communication systems based on:
– visible light
– infrared
– microwaves
– radio waves
Fibre optic systems use light
A simple transmitter:
button cell & LED
A simple detector:
phototransistor + multimeter
Infrared light is used more commonly than visible light - less
attenuation and dispersion.
Definitions
1.Analog signal
Analog signal is the signal, in which voltage or
current varies continuously with time.
2.Digital signal
Digital signal is the discontinuous signal, which has
only two levels, high and low or one and zero.
3.Baseband signal
The electrical equivalent of original information (For
example, sound) is known as Baseband signal.
Elements of Basic Electronic Communication System
Noise in Communication System and Types
Noise is an unwanted electrical signal which gets added
to the transmitting signal while travelling.
Due to noise the quality of transmitted information will be
degrade.
Types of Electronic Communication
Classification based on Direction of
Communication
Depending on direction used for communication, the
communication system is classified as:
Comparison of communication system
The Electromagnetic Spectrum
The frequency of EM signal ranges from few Hertz
to several GHz. This entire range of frequencies of
EM waves is called Electro-magnetic spectrum.
Segments of EM spectrum
EM Spectrum and Applications
Concept of Transmission Bandwidth
Transmission bandwidth is that portion of the
electromagnetic spectrum occupied by a signal.
Transmission bandwidth is also the frequency range
over which an information signal is transmitted or
over which an a receiver or other electronic circuit
operates.
B/W Continued….
ANY QUESTIONS?