Radio Broadcasting, Transmission and Reception
Radio communication means the radiation of radio swells by the transmitting station,
the propagation of these swells through space and their event by the radio receiver.
Fig-1 shows the general principles of radio broadcasting, transmission and event.
As a matter of convenience, the entire arrangement can be divided into three corridor viz.
transmitter, transmission of radio swells and radio receiver.
Transmitter is an extremely important outfit and is house in the broadcasting station.
Its purpose is to produce radio swells for transmission into space.
The important factors of a transmitter are microphone,
audio amplifiers, oscillator and modulator ( See Fig-1).
A microphone is a device which converts sound swells into electrical swells.
When the speaker speaks or a musical instrument is play.
The varying air pressure on the microphone generates an audio electrical signal
which corresponds in frequence to the original signal.
The affair of microphone is fed to a multistage audio amplifier for raising the strength of weak signal.
(ii) Audio amplifier-
The audio signal from the microphone is relatively weak and requires modification.(Radio Broadcasting)
This job is fulfilled by protrud audio amplifiers. The amplified affair from the last
audio amplifier is fed to the modulator for rendering the process of modulation.
( iii) Oscillator-
The function of oscillator is to produce a high frequence signal, called a carrier surge.
Generally, a demitasse oscillator is use for the purpose.
The power position of the carrier surge is rise to a sufficient position by radio frequence amplifier stages (not shown in Fig-1).
Utmost of the broadcasting stations have carrier surge power of several kilowatts.
Similar high power is necessary for transmitting the signal to the required distances.
The amplified audio signal and carrier surge are fed to the modulator.
Then, the audio signal is superimpose on the carrier surge in a suitable manner.
The attendant swells are call modulate swells or radio swells and the process is call modulation.
The process of modulation permits the transmission of audio signal at the carrier frequence.
As the carrier frequence is veritably grandly, thus, the audio signal can be transmit to large distances.
The radio swells from the transmitter are fed to the transmitting antenna or upstanding from where these are radiate into space.
2.Transmission of radio swells
The transmitting antenna radiates the radio swells in space
in all directions.
These radio swells travel with the haste of light i.e. 3 × 108 m/ sec.
The radio swells are electromagnetic swells and retain the same general parcels.
These are analogous to light and heat swells except that they've longer wavelengths.
It may be emphasis then that radio Swells are transferred without employing any line.
It can be fluently show that at high frequence, electrical energy can be radiate into space.
On reaching the entering antenna, the radio swells induce bitsy e.m.f. in it.
This small voltage is fed to the radio receiver.
Then, the radio swells are first amplify and also signal is uproot from them by the process of demodulation.
The signal is amplified by audio amplifiers and also fed to the speaker for reduplication into sound swells.
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