Transmission modes- Callum Pilling

Transmission modes- Callum Pilling

1. Simplex transmission

   • sends data in one direction only. A radio broadcast is a good example of simplex transmission

2. Half-duplex transmission

   • allows two-way transmissions but the devices don’t transmit at the same time. A system being used to monitor and control manufacturing processes can use half-duplex transmissions. It will send a message to the control computer, which will respond with new settings, but they both cannot send messages at the same time. Some network systems use half-duplex to maximise bandwidth.

3. Full duplex transmission

   • allows two-way communication at the same time. The telephone system, land or mobile, is an example of a full duplex system.

4. P arallel and serial transmission

   • In parallel transmission, a number of bits of data are transmitted simultaneously over an equal number of wires/channels. This allows the bits in a whole byte of information to be transmitted together. It has a short range, with an absolute maximum of around 5 metres.
   • Parallel transmission used to be popular for connecting printers to computers but it is rarely used these days in computing because of its cost and limited range.
   • In serial transmission, bits are transmitted one at a time over a single wire/channel. This reduces the cost of the cable, but gives a slower rate of data transfer. There is also some additional complexity, as bytes have to be disassembled into individual bits for transmission and then reassembled after receipt. Serial transmissions can be used over large distances.
   • Byte – In computing and telecommunications, a byte is unit of digital information which commonly consists of eight bits. (See page 19 for a defi nition of bits.)

5. Transmission modes

6. There are three common modes of transmission:

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