Radio communication and the Mobile Phone<br />By Mike Ham<br />
Radio waves<br />Radio waves are electromagnetic radiation consisting of wavelengths in the electromagnetic spectrum which are longer than infrared light. They travel at the speed of light and can be received by radio stations.<br />Radio waves are emitted by man made sources and natural sources such as lightening. They are an important part of our every day lives.<br />Radio waves can be received in either amplitude modulation (AM) or Frequency Modulation (FM)<br />
Radio frequencies are measured in Hertz (Hz) where one Hz is one oscillation per second. 1KHz a thousand, 1 MHz is a million, and 1GHz is a thousand million. <br />Telecommunication such as broadcast radio, television Frequencies consist between 30 kHz and 300 GHz.<br />In the UK, AM radio uses frequencies between about 180 kHz and 1.6 MHz, FM radio ranges from 88 to 108 MHz, and TV ranges from 470 to 854 MHz.<br />
Radio communication using AM<br />A radio frequency wave used for communication is also know as a carrier wave.<br />Radio waves carry embedded codes or messages that act as codes. It does this by modulation<br />For Amplitude Modulation (AM) the electrical signal for example a microphone for music or speech, is used to make the amplitude of the carrier wave different according to the modulating signal.<br />
How does a mobile phone network use radio communication?<br />Radio communication can be used with mobile phones by sending and receiving it.<br />Radio frequency signals from the phones are transmitted to the nearest base station and signals such as speech can be transmitted back as well.<br />Once the signal reaches the base station, it is then transmitted to the main telephone network via cables or higher frequency radio links.<br />
Each location in the world has a hexagonal cell and each base station provides radio coverage to the different cells.<br />To ensure users remain within the range of base station, the cells overlap. If base stations aren't in the correct place mobile phones would not work. <br />When a person moves out of range from one cell, the controlling networks hand it over communications to the next base station.<br />
Refrences<br />Cell network diagram [Online image]. Available from: http://www.sitefinder.ofcom.org.uk/mobilework.htm [26/01/11].<br />Clip art phone and radio tower [Clip art image]. Available from: PowerPoint [26/01/11].<br />Modulation and carrier waves [Online image]. Available from: http://www.sitefinder.ofcom.org.uk/mobilework.htm [26/01/11].<br />PUBLIC TELECOMMUNICATION NETWORKS UNIT (2001) How Mobile Phone Networks Work [WWW] Ofcom. Available from: http://www.sitefinder.ofcom.org.uk/mobilework.htm [Accessed 21/01/11].<br />Radio waves [online image] Available from: http://www.astro.cornell.edu/academics/courses/astro2201/images/wave-freq.gif [accessed 21/01./11]<br />What is a radio wave? [WWW] available from: http://en.wikipedia.org/wiki/Radio_waves[accessed 21/01/11]<br />
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.