1. Radio Communication and Mobile phones By Chirag Thakar

2. What are Radio Waves? Electromagnetic waves are emitted by many natural and man-made sources and play a very important part in our lives. All radio wave radiation consists of fluctuating electric and magnetic fields and the frequency, which is the number of times per second at which the wave fluctuate, determines on their properties and the use that can be made of them.

3. …Continued Frequencies are measured in hertz or Hz, where 1 Hz is one oscillation per second, 1 kHz a thousandetc. We use the frequency 30KHz and 300 GHz telecommunication, radio and television.

4. Radio Communication Radio frequency used for communication is ‘carrier wave’ which is produced by a transmitter as a sine wave. If the radio wave is to convey more information, such as speech or computer data etc., this information has to be added to the carrier wave in some way, a process known as modulation.

5. Modulation Modulation is where a signal is suitable for sending over a transmission medium Reasons for modulation: Frequency translating Improving signal/noise ratio by increasing the bandwidth Multiplexing

6. Mobile Phones Using Radio Communication Mobile phones send and receive information using radio communication. The radio signals are transmitted from the phone to the nearest base station, then connected to a main telephone network. Each base station provides radio coverage to a geographical area known as a cell.

7. …Continued Transmitted signal strength falls off rapidly with distance from base stations, and mobile phones require a certain minimum signal strength to ensure adequate reception.

8. References J.E.Flood and P.Cochrane (1992) Transmission systems London: Peter Peregrinus Ltd. PUBLIC TELECOMMUNICATION NETWORKS UNIT (2001) How Mobile Phone Networks Work [WWW] Ofcom. Available from: http://www.sitefinder.ofcom.org.uk/mobilework.htm [Accessed 18/01/11].