Transmission modes

Transmission Modes

There are three modes of data transmission that corresponding to the three types of circuit available.

these modes are :-

1) Simplex :-

                     In simplex communications mode, there is a one way communication transmission. Television transmission is a very good example of simplex communication. The main transmitter sends out a signal                    (broadcast ), but it does not expect a reply as the receiving units cannot issue a reply back to the transmitter.

it requires one wire only.

2) Half-duplex :-

                           In half-duplex mode, both units communicate over the same medium, but only one unit can send at a time. While one is in send mode, the other unit is in receive mode. It is like two polite people talking to each other -- one talks, the other listens, but both of them could not talk at the same time.

It requires two wires. This is the most common type of transmission for voice communications.

The transmission of data to and from a hard disk is also done in half duplex mode.

3) Full-duplex or Duplex :- 

                                          A full-duplex system is used that allows information to flow simultaneously in both directions on the transmission path. Use of a full-duplex line improves efficiency as the line turn-around time required in a half-duplex arrangement in eliminated.

It also requires four wires for full-duplex system.