Topic 10-Communications Flashcards
What are optical fibres?
Optical fibre links work by sending phone signals via infrared waves along optical fibres. The infrared waves reflect off the inside surfaces of the fibre. In order for optical fibres to work across the globe, long cable made up of thousands of tiny strands of glass- fibre have been laid across continents and under the oceans - connecting up the world!
Optical fibres communications are much quicker than satellite communications, but both systems introduce a time-delay into the signals.
What are satellite communication?
Satellite communication work using microwaves. They are put into geosynchronous orbit. This means that the satellites takes 24hours to complete its orbit - the same time as the earth takes to rotate microwaves signals are sent from an earth station dish,the microwave signal is detected by the satellite and then re-emitted by another dish on the satellite back towards the earth
How do mobile phones work?
Mobile phones work by transmitting low power microwave signals to a local base station mast. All base stations are connected at a mobile telephone switching office (MTSO) and these communicate with each other via optical fibre connections. The mobile phone signal is sent to its nearest base station which then sends out another microwave signal to the recipient phone.
Signals sent via optical fibres have advantages over traditional telephone signals sent via wire because:
1) fibres optic lines use less energy
2) they need fewer boosters
3) there is no cross-talk (interference) with adjoining cables
4) they are difficult to bug
5) their weight is lower is so they ate easier to install.
