The main features of a range of transmission media and modes of data transmission on a network
The form of communication link used to communicate between two or more stations. EG. Radio/TV broadcasts, copper cable (twisted pair/coax), fibre optic (FDDI), microwave, infra-red, satellite, cellular telephone network.
Each device on a network is connected to a transmission cable to allow messages to be sent from one device to another.
LANs typically use:
- Twisted pair
- fibre optic
The differences between these media relate to:
- ease of installation
- resistance to interference
Networks can also use wireless media such as:
- radio frequencies
which do not require a physical link.
There are several configuration settings which affect the mode of transmission.
Flow control and cable provisions affect the type of exchanges between stations. Simplex is a one-way mode of transmission; duplex is two way; half duplex enables two-way transmission but not for each station simultaneously; asymmetric duplex is two-way but with different speeds each way. Asynchronous transmission sends a character at a time with markers either end; synchronous systems are used to speed up this process and send whole blocks of data at a time by timing the start and end of the block. Cable types and facilities affect the type of transmission. Serial transmission sends each bit of data down the same cable in sequence; parallel transmission enable the eight data bits to travel along separate cables simultaneously.