Transmission Media

Computer Science: OCR A Level, topic 3.3.17

Transmission media are different ways of physically transferring data along a network.

This is often referred to as 'Ethernet cable'.
Inside the cable, there are eight wires which are twisted into pairs. This is to reduce interference from other signals and improve transmission speed.
Twisted cables have different ratings to indicate how quickly data can be transferred.
E.g. Cat-5e can transmit at 1 Gbps.
E.g. Cat-6 can transmit at 10 Gbps.

Fibre-optic cables are made of thin strands of glass which transmit binary data as pulses of light.
Fibre-optic cables have many advantages:
Do not suffer interference.
Very high bandwidth (100Tbps).
Because of the lack of interference, fibre-optic cabling is appropriate for long distance communication such as undersea cabling.

Radio waves are the transmission media of wireless networking.
E.g. WiFi.
E.g. Bluetooth.
The amplitude (strength) of a radio wave decreases as it moves further from its transmitter. This is why WiFi signal loses strength further away from a WAP.
Radio waves are also subject to interference from other radio signals of similar frequency. Wireless access points (WAPs) often check for frequency channels that are least congested before starting a broadcast.

Coaxial cable is a wired transmission media where an insulated copper wire is surrounded by a metal mesh to protect it from interference.
This is most often used for cable television.

Test yourself on Transmission Media