2. Introduction to radio waves Radio waves are the lowest energy form of the electromagnetic spectrum and are incredibly important in the telecommunications industry. Radio’s frequency range is typically between 30KHz and 300 GHz. A diagram of the electromagnetic spectrum, with radio waves at the far left of the spectrum.
3. Radio Waves Radio waves are used in a variety of communications systems, from television broadcasts to mobile phone networks. The radio wave frequencies are split up into bands, each of these bands is allocated for different uses, the chart below illustrates the different uses for each band. A chart showing the different radio bands in the radio frequency.
4. Amplitude Modulation Amplitude modulation works by varying the amplitude of the carrier wave to convey the required information. Other methods of modulation exist, such as frequency modulation which varies the frequency of the carrier wave to convey the signal. Amplitude modulation provides the cheapest and simplest means to broadcast. However, it is prone to interference. A graph demonstrating Amplitude Modulation.
5. Mobile Phone Networks A mobile phone sends and receives signals via radio waves. Radio frequencies are emitted from the phone containing voice signals, the signals are received by a base station and the response relayed back to the phone at a different frequency. A mobile phone network consists of a grid of hexagonal “cells”. Each cell represents a specific geographical area and each cell overlaps to ensure the user is always in range. The radio waves containing the speech signals are sent back and forth from base stations as a user move from one cell to another. A diagram of a mobile phone network.
6. references ANON (n.d) Image of Electromagnetic Spectrum [Online image]. Available from: http://www.kollewin.com/blog/electromagnetic-spectrum/ [27/01/2011]. ANON (n.d) Radio Band Frequencies[Online image]. Available from: http://en.wikipedia.org/wiki/Radio_spectrum [27/01/2011]. PUBLIC TELECOMMUNICATION NETWORKS UNIT (2001) How Mobile Phone Networks Work [WWW] Ofcom. Available from: http://www.sitefinder.ofcom.org.uk/mobilework.htm [Accessed 27/01/11].
