Radio Broadcasting

Posted on November 25, 2009 by greenstoneradio.
Categories: Radio, Radio broadcasting.

Radio broadcasting is a means of transmitting audio signals via the air as radio waves. These radio waves travel from a transmitter to an antenna and from there are sent to a receiving device to be interpreted.

Radio waves are a form of electromagnetic radiation with a very high frequency. They are invisible to the human eye and sit above infrared waves in the electromagnetic spectrum. They provide a relatively simple and inexpensive way to transmit signals to wide audiences.

Whilst radio stations are commonly known as public systems there are also many stations that exist for non-broadcast purposes, such as base stations used by the emergency services, dispatch stations used by truck and taxi services, amateur radio stations and emergency broadcast systems.

The two primary types of radio station are AM and FM stations.

AM radio stations were the earliest wide-scale broadcasting systems to be developed. AM stations use amplitude modulation to change the radio carrier signal so that it can be interpreted by the listener.

A key advantage of AM radio stations is that the signal being transmitted is relatively unsophisticated, and as such it can be detected and decoded with basic equipment. However, this simple signal is vulnerable to interference by bad weather.

FM radio stations use frequency modulation to alter the radio carrier signal and broadcast a message. FM stations broadcast in the VHF (Very High Frequency) range of airwaves in the frequency range of 88 MHz to 108 MHz.

FM radio was invented in the 1930s by Edwin Armstrong with the sole purpose of solving the interference problems inherent in AM radio. FM radio is almost immune to this interference and has also achieved greater signal clarity by spacing radio stations further apart than AM stations.

The emergence of the Internet has prompted radio stations to broadcast online. Since the 1990s radio stations have been broadcasting on the Internet where they do not suffer from the licensing restrictions applied to other stations, and there is no need to setup air transmission equipment to be able to broadcast to the world.