Radio communication and the mobile phone

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Radio communication and the mobile phone

  1. 1. Radio communication and the mobile phone<br />Lucy Standring<br />
  2. 2. RADIO Communication<br />Radio as a form of communication has been apparent for over 100 years.<br />Guglielmo Marconi made the first radio transmission in 1895.<br />Within 30 years of this first transmission radio was being used in everyday life for broadcasting as well as communication within the police and military.<br />
  3. 3. How radio communication works<br />The frequency wave used for radio communication is called a carrier wave.<br />These waves are produced and transmitted from the transmitter as a sine wave.<br />A sine wave is only able to convey minimal information, but can be switched on and off, which was used within the Morse code process.<br />If more information is needed, modulation needs to occur (see the next slide for more information).<br />Within modulation some aspect of the carrier wave much be varied, for example for FM it is the frequency.<br />
  4. 4. Amplitude modulation<br />This is the process of attaching information to a carrier wave ready for transmission.<br />Amplitude modulation is carried out to allow more data to be transmitted.<br />Within the process the amplitude of the carrier wave is varied.<br />This is done within accordance of the information being transmitted (for example speech and music tracks).<br />
  5. 5. Electromagnetic waves<br />Electromagnetic waves are received and emitted by mobile phones and their base stations.<br />They can be emitted by natural sources (such as the warmth from the sun), as well as man-made sources (such as mobile phones).<br />They are made up of oscillating (vibrating rapidly) electric as well as magnetic fields. The frequency of these fields determines their properties and use.<br />We also see using part of the electronic spectrum, which the eye detects as visible light.<br />
  6. 6. Mobile phone networks<br />Mobile phones send and receive data (text messages, voice messages etc.) via radio communication.<br />Radio frequency signals containing the data are firstly sent from the phone to the nearest base station.<br />These signals are then transmitted to the main telephone network, by either:<br />- telephone cables<br />- higher frequency radio links between an antenna at base station and another at a terminal connected to the main telephone network<br />
  7. 7. Base stations<br />Every base station provides radio coverage a specific area.<br />Connected to one another by central switching centres. <br />These central switching centres track calls and transfer them to different base stations as the callers moves around.<br />Base stations cells overlap, to ensure mobile phone users are always within range of one.<br />Size of the cell for a base station depends on:<br />- Local terrain – Signals can be blocked by trees, buildings etc.<br />- Frequency band the network operates in.<br />- Capacity needed in the given area.<br />Typically spaced between 0.2-0.5km apart in towns and 2-5km apart in the countryside.<br />
  8. 8. Key words<br />Electromagnetic waves – AKA radio waves, contain both electric and magnetic fields, can be emitted and received.<br />Frequency – The number of wave oscillations per second, measured in Hz (hertz).<br />Carrier wave – A radio wave that can be modulated in order to transmit information.<br />Sine wave – Waveform which looks like a sine curve<br />Modulation – Varying an aspect of a carrier wave, for example amplitude, frequency etc.<br />
  9. 9. References<br />PUBLIC TELECOMMUNICATION NETWORKS UNIT (2001) How Mobile Phone Networks Work [WWW] Ofcom. Available from: http://www.sitefinder.ofcom.org.uk/mobilework.htm [Accessed 26/01/11]<br />PANDA (n.a.) Marconi Guglielmo[Online image]. Available from: http://panda.unm.edu/Courses/Finley/pix/MarconiGuglielmo.jpg [Accessed: 26/01/11].<br />WIKIMEDIA (n.a.) Amplitude modulation [Online image]. Available from: http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/Amplitude_modulation.svg/585px-Amplitude_modulation.svg.png [Accessed: 26/01/11].<br />TODAYIFOUNDOUT (n.a.) Electromagnetic spectrum [Online image]. Available from: http://www.todayifoundout.com/wp-content/uploads/2010/08/114284main_EM_Spectrum500.jpg [Accessed: 26/01/11].<br />

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