radio link communication
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RADIOLINKING
COMMUNICATION
COMPUTER NETWORKS
BY-:
ANURAG BHATOA - 2901
NEHA DHIMAN - 2902
USHA DOGRA - 2904
ANISH JABBLE - 2906
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RADIO TRANSMISION
A radio communication system sends signals by radio
waves.
Types of radio communication systems deployed depend on
technology, standards, regulations, radio spectrum
allocation, user requirements, service positioning, and
investment.
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The radio equipment involved in communication systems
includes a
1. Transmitter
2. Receiver
Each having an antenna and appropriate terminal equipment
such as a microphoneat the transmitter and a loudspeaker
at the receiver in the case of a voice-communication system.
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EARTHS SURFACE
Ground Wave
In the VLF, LF, and MF bands, radio waves follow curvature
of earth.
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EARTHS SURFACE
IONOSPHERE
In the HF band, they bounce off the ionosphere.
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TRANSMITTER AND RECEIVER-:
A transmitter is an electronic device which, usually with the
aid of an antenna, propagates an electromagnetic signal such
as radio, television, or other telecommunications.
A radio receiver is an electronic circuit that receives its input
from an antenna, uses electronic filters to separate a wanted
radio signal from all other signals picked up by this antenna,
amplifies it to a level suitable for further processing, and
finally converts through demodulation and decoding the
signal into a form usable for the consumer, such as sound,
pictures, digital data, measurement values, navigational
positions, etc.
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An RF (radio frequency) link is a electronic device which
has the capability to send and/or receive data/signals without
the use of wires. Currently there are 3 types of radiofrequency link :
433.92 MHz - suitable for transmission of audio and other
data signals.
2.4000 - 2.4835 GHz (ISM-Band) - suitable for
transmission of both static images and moving video signals.
Transceiver Sets - a transceiver is a device that is able to
both transmit and receive radio frequency signals. The use of
transceivers makes possible the bi-directional transfer of
information enabling applications such as telephony and the
remote control of electronic devices.
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HOW RADIO COMMUNICATION WORKS
Radio electromagnetic waves are used because they cantravel very large distances through the atmosphere without
being greatly attenuated due to scattering or absorption.
Radio receives the radio waves, decodes this information,
and uses a speaker to change it back into a sound wave.An illustration of this process is given below:
A sound wave is produced with a frequency of 5 Hz - 20
kHz.
A microphone converts the sound wave into an electrical
signal.
The electrical wave traveling through the microphone wire is
analogous to the original sound wave.
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The electrical wave is used to encode or modulate a high-
frequency "carrier" radio wave. The carrier wave itself does
not include any of the sound information until it has been
modulated. The carrier wave can either be amplitude
modulated (AM, top) by the electrical signal, or frequency
modulated (FM, bottom).
The signal is transmitted by a radio broadcast tower. Radio contains an antennato detect the transmitted signal, a
tunerto pick out the desired frequency, a demodulatorto
extract the original sound wave from the transmitted signal,
and an amplifierwhich sends the signal to the speakers.
The speakers convert the electrical signal into physical
vibrations (sound).
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RADIO SYSTEM
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ADVANTAGES
Easy to generate.
Can travel long distances.
Can penetrate buildings easily, used for both indoors and
outdoors.
Are omnidirectional , so do not have to carefully aligned
physically.
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DISADVANTAGES
At high frequency radio waves tend to travel in straight lines
and bounce off obstacles.
Power falls off sharply with distance from the source ,
roughly as 1/r2 in air.
At all frequencies, radio waves are subject to interferencefrom motors and other electrical equipment.
Also absorbed by rain.
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CLASSICAL VS. MODERN-:
Classical radio communications systems use frequency-
division multiplexing (FDM) as a strategy to split up and
share the available radio-frequency bandwidth for use by
different parties communications concurrently.
Modern radio communication systems include those thatdivide up a radio-frequency band by time-division
multiplexing (TDM).
These systems offer different tradeoffs in supporting
multiple users, beyond the FDM strategy that was ideal for
broadcast radio but less so for applications such as mobile
telephony.
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THANKYOU
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