A communication system consists of an information source that generates messages, a transducer to convert the information to an electrical signal, a transmitter to process and transmit the signal, a channel to carry the signal between transmitter and receiver, and a receiver to reproduce the original signal. Mobile phones use radio waves transmitted through antennas to communicate with each other over mobile networks.

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MODULE-05
18ELN14

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DIGITAL ELECTRONICS FUNDAMENTALS

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Communication System
Communication : Transfer of useful information between two points.
They are basically classified as
1) Wired communication : Media or channel is through wire
2) Wireless Communication : Media is Air

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Communication System
Information source:
Messages are in the form of words, picture sound signal, video etc.
Transducer:
Information signals are not electrical in nature , a device which
converts one form of signal to another form is called transducer.
Here transducer used to Convert signal to electrical form for
transmission
Transmitter:
The main function of transmitter is to process the electric signal like
Modulation, amplification and filtering to make it capable to
transmit signal over long distance.

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Communication System
Channel: This medium is either wired (twisted pair, co-axial,
Optical Fiber Cable (OFC), etc.) or wireless (free space, radio
communication, etc.), through which the message travel from the
transmitter to receiver.
Noise: It is an unwanted signal which distort the message signal.
They can interface with signal at any point in a communication and
are unpredictable in nature.
Receiver: The main function of receiver is to reproduce the
massage signal in electrical form. It performs the functions like de-
modulation, filtering, amplification, etc. Ex: loud- speaker

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Communication System
Principles of Operation of mobile phone
 Mobile phones use radio waves to communicate
 Radio Waves are Electromagnetic Waves ,where data is in
oscillating electric and magnetic field form
 Mobile phones transmit radio waves in all direction by built
in radio antenna
 An antenna converts an electric signal to the radio wave
(transmitter) and vice versa (receiver).
 Modern smart phones also contain more than one type of
antenna. In addition to the cellular antenna, they may also
have Wi-Fi, Bluetooth and/or GPS antennas.

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Communication System
Mobile Network
Topology

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