Optical Communication Methods Chapter 3

This presentation will: Help you understand different types of optical communication methods including: Infrared Fibre optic Laser It will help you understand their advantages and disadvantages and typical applications.

Introduction There are many way of communicating between devices. Some methods make use of light to transmit data from one source to another source.

Infrared This type of technology has been around for many years and are often found in remote controls for televisions and some computer consoles. Xbox http://www.republicofcode.com/tutorials/photoshop/xbox360/10.jpg TV http://gfreak.files.wordpress.com/2008/07/sony_bravia_d3000_1.jpg Remote http://www.freewebs.com/xbox360country/remote.jpg Click!

Infrared X  Early mobile phones used infrared technology to allow data transfer to take place. People used to share contacts and play games using infrared technology. This soon became redundant because of the introduction of Bluetooth technology (covered in next lesson). One of the limitations of infrared technology was that it needed direct line of site and wouldn’t work over more than 10 metres. Bandwidth was also very slow with a maximum speed of 115.2kbps. Communication can’t take place if something gets in the way.

Fibre Optic Introduced in a previous lesson... This method of communication at speeds which have not been beaten by other optical communication methods. This type of technology is mainly used were large distances are covered (over 100 metres). You can find fibre optic cables in a lot of house holds which have an entertainment unit. Fibre optic cables are often used to transmit the sound from the device (such as a blu-ray player) to the amp.

Laser These work by having two laser devices in direct line of sight to each other. Each device can send and receive laser beams to each other. Data is transmitted at the speed of light (like in fibre optics) but doesn’t need a physical connection. Laser technology is easy to set up and is portable which means they could be used in different locations. A TV crew could film an event and send the footage back to a satellite van which can then transmit to the station. Video sent to receiver Stadium http://elitechoice.org/wp-content/uploads/2008/08/wembley-stadium.jpg

Laser Lasers work incredibly well but only when atmospheric conditions are right. Problems often occur when the weather isn’t at its best. Although they aren’t all that common, there have been experiments to communicate between satellites in space. Bandwidths can reach speeds of around 1.5Gbps at distances of up to 4km.

Activity Describe the following optical communication methods: Infrared Fibre Optic Laser Remember: Identify, Amplify and Exemplify Complete the following table Method Advantage Disadvantage Where is it used? Infrared Fibre Optic Laser

Example exam questions Give three situations when infrared might be used. Give two situations when fibre-optic cables might be used. Give three situations when laser might be used for communications.