Radio Transmission

WHAT IS RADIO?

• “Radio\” is a gadget or, electronic device that we listen to.
• Technically Radio is a method of transmitting electrical energy from one place to another without using any kind of direct, wired connection.
• There are two main devices used in radio transmission; one is transmitter and another is receiver
• Transmitter sends out a radio wave through the air—maybe from one side of the world to the other—and completes its journey when it reaches to receiver.
• When we extend the antenna (aerial) on a radio receiver, it catches some of the electromagnetic energy passing by. When we tune the radio to a station, an electronic circuit inside the radio selects only the program that we want from all those that are broadcasting.
• A radio set is equipped with electronic components that catches radio waves sailing through the air, and converts them back into sounds we hear.

RADIO WAVES

• Radio waves carry energy as an invisible, up-and-down movement of electricity and magnetism, much like ocean waves.
• The huge transmitter antennas of the radio station transmits program signals which are carried by radio waves, travelling at a speed of light, to the smaller antenna on our radio set.
• The size of a wave is called its amplitude.
• Frequency is the number of wave cycles that are completed in one second.
• When a radio program is added to the carrier in such a way that the program signal causes fluctuations in the carrier\’s frequency, it is called frequency modulation (FM).

• When peaks of the carrier wave are make bigger or smaller the process is known as amplitude modulation (AM).

AM & FM MODULATION

• Two characteristics, amplitude and frequency, mark the difference between AM and FM radio. AM stands for amplitude modulation, which means the amplitude of the radio signal is used to encode information. FM denotes frequency modulation, which uses a change in frequency to encode information.
• Modulation is the variation of some property of the radio carrier in a manner that conveys information. Both AM and FM radio use modulation to encode information.
• The AM radio are in the frequency range of 535-1605 kHz, assigned at 10 kHz intervals, while the FM radio band is from 88 to 108 MHz.
• AM and FM radio differ in performance, specifically with regard to sound quality and the broadcast range. FM stations tend to sound better than AM stations as it use a high frequency range, but AM stations can usually be heard farther away.