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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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Documents

Radio Link Communication