Electronics - Radio

Radio
Points : Definition, Component of Radio Transmission, Radiobroadcast (Radio transmission), Relay of Message, Modulation, Reception of the Message

Definition
A radio set is an electronic device, which is designed to receive radio or electromagnetic waves in the radio range.

Component of Radio Transmission:
Radio transmission requires following two parts.
• An Antenna at a broadcasting station (Transmitter)
• A receiver (Radio Set)

Radiobroadcast (Radio transmission)
Process of radiobroadcast can be divided into following two steps.
• Relay of message
• Reception of message

1. Relay of Message:
Low frequency sound ranging from 20 Hz to 200KHz produced at broadcast station called audio frequency sound, converted into electrical oscillation by a microphone.

Modulation
Audio frequency waves cannot be efficiently transmitted through the space. Thus for the purpose of transmission the audio frequency electrical waves from microphone are impressed upon carrier waves so that the amplitude of thee Radio frequency carrier waves varies with the frequency of A.C. current.


Modulation Definition
This process of impressing the audio frequency message on a radio frequency carrier wave called Amplitude modulation and the resultant wave is called a modulated carrier

2. Reception of the Message
When the modulated carrier waves meet at a receiving aerial, they generate fluctuating alternating current in it. This fluctuating alternating current turns into direct current by a suitable rectifier. This direct current fluctuates in harmony with the changing amplitude of the radio waves these waves causing the earphone to reproduce the sound this is called demodulation.