Lesson 9 - Data Exchange

Lesson 9 - Data Exchange

1. CODEC

   • A device/program used to code or decode data. its the software required for VoIP. This program is used, where necessary, to digitise an analogue voice signal, then compress it and split it into internet packets for transmission. it then performs the reverse at the receiving end.

2. 3 transmission modes used in communication

   • Simpex
     • Sends data in one direction only, for example radio broadcast
   • Half Duplex
     • Allows two-way transmissions but the devices don't transmit at the same, for example a system that monitors and controls manufacturing processes. It sends messages to the control computer which will respond with new settings but they both cannot send messages at the same time. May use half duplex to maximize bandwidth.
   • Duplex (Full Duplex)
     • Allows two-way communication at the same time, for example the telephone system, landline, mobile

3. Wired

   • Fibre Optic
     • :) Fast, works over long distances, little interference.
     • :( Complex connection and termination equipment.
     • For example: cable networks use from their source to the distribution panels in the street.
   • Coaxial
     • :) Fast, reliable.
     • :( More expensive than other options, susceptible to noise.
     • For example: connection to cable TV networks, aerial connection to TV

4. Wireless

   • Satellite
     • :) Can increase the distance a network can reach
     • :( Expensive.
     • For example: Global communication systems
   • Microwave
     • :) Signal degrades very little over long distances
     • :( Devices must be in a direct line of sight. Can be affected by rain, pollen and sun spot activity. Suffer from external interference.
     • For example: Earth to satellite communication. Bluetooth.