1. Chapter 3

2.  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.

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

4.  This type of technology has been around for many years and are often found in remote controls for televisions and some computer consoles.

5.  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.

6.  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.

7.  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

8.  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.

9. MethodAdvantageDisadvantageWhere is it used? Infrared Fibre Optic Laser

10.  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.