Network Devices
Transmission Media
Transmission media are the paths that carry data between devices in a network. Without a medium there is nothing for the data to travel along, so every link in a network is made of one. Each medium carries the data as a signal in a form that suits it, and the network hardware at each end, such as the NIC, turns the data into that signal and back again.
The three media
| Medium | Form the data travels in | Example use |
|---|---|---|
| Copper cable | Electrical signals | A fixed desktop computer in a dance studio wired to a wall socket |
| Fibre optic cable | Pulses of light through glass or plastic | A media department sending large video files to its main data store |
| Wireless | Radio waves through the air | A card reader carried by a waiter moving between tables |
Copper is the cheaper of the two cables and is fine for ordinary amounts of data over short runs. Fibre costs more but carries far more data and keeps the signal strong over long distances, which is why it is chosen when huge files have to travel a long way. Wireless needs no cable at all, so it is usually the only sensible choice when a device has to move around, but the radio waves must travel through the air to reach the network, so the device has to stay in range.
Choosing the right medium
Think about what the device does and where it is. A device that never moves and sits near a socket can use copper cable. A link that must shift enormous amounts of data a long way, such as a media department sending video to a data store, is better on fibre optic cable. A device that is carried from room to room cannot be tied to a cable, so it uses wireless. A wireless link still has a medium: the radio waves travelling through the air, not a cable.
Practise this
OCR GCSE Computer Science · Network Devices