hsc ipt communication systems presentation matched to the NSW BOS syllabus

1. Communication System Communication Systems support people who are working together by enabling them the electronic exchange of data and information. This presentation will enable the users to access a wide range of information regarding Communication Systems.

9. Examples of Communication Systems

14. Transmitting and receiving in communication systems:

16. Serial Transmission Data is transmitted, on a single channel, one bit at a time one after another - Much faster than parallel because of way bits processed (e.g. USB and SATA drives) Sender Transmitted Receiver received 1 0 1 0 0 1 1 0

18. Simplex: One direction only Transmission Direction Half duplex: Both directions but only one direction at a time

19. Full duplex: send and receive both directions at once

20. 3 Types of LANs RING – consists of nodes in a closed loop or circle. Each node is part of a loop linking all the nodes together and nodes are attached to the cable at various points around the ring. Traffic can be one-way around the loop or can travel in both directions if a double loop is used. Its advantages include: a single cable is used to connect all the nodes making it extremely cheap, takes up less space and easy to fault-find in terms of broken cable. Its disadvantages include: if the ring is broken or cable is faulty the network ceases to operate, the ring must be broken to add or remove nodes, and it’s slow as it goes around the entire circle. STAR – is a network topology that consists of computers attached to a central point or node (a device such as a computer connected to a network) which can be a computer like a mainframe, hub with links going out to computers that are workstations and servers. Star networks are popular and most common in LANs. Its advantages include: each node has its own cable and doesn’t need to share the line with other nodes, if a cable to a node is broken then only that node is affected while the rest of the network can operate normally, new links to the central node can be easily added or existing links easily removed without affecting the rest of the network. Its disadvantages include if the central node fails then the entire network will cease to operate, more cabling is needed than for other network topologies which is uneconomical.

21. BUS – this uses a cable in single line with two end points. At each end point there is terminator that prevents signals at the end of the cable from being reflected back into the network. In a BUS network each node is connected to a single cable and it is mostly used for small LANs. Its advantages include: it’s easy and cheap to set up as it requires less cables, nodes can be easily added and removed and if a node goes down the network is unaffected. Its disadvantages include: because the one cable carries all the data, collisions (data traffic jams) become more common as more nodes are added or when multiple terminals transmit at the same time. Nowadays, bus networks are often replaced with a star network

23. NETWORK TOPOLOGIES (categorizing by shape)

24. Other information processes in communication systems

28. Issues related to communication systems