Transmission modes

Transmission modes

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 transmission but the devices dont transmit at the same time. A system being used to monitor and control manufacturing processes can use half-duplex transmissions. it will send messages to the control computer, which will respond with new settings, but they both cannot send messages at the same time which will respond with new settings, but they both cannot send messages at the same time. some networks systems use half-duplex to maximise bandwidth.

3. Full-duplex transmission: allows two-way commmunicatin at the same time. the telephone system, land or mobile. is an example of a full-duplex system.

4. Parallel and serial transmission

   • In parallel transmission, a number of bits of data are transmitted simultaneously over an equl number of wires/channels. this allows the bits inh 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 ar 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 transmission can be used over large distances.

5. Universal serial bus (USB)

   • Serial transmission method which was introduced to make many of the connections to a computer look the same. used in a variety of devices, such as, mobile phones, memory sticks and mp3 players. they also supply some power to devices.