Digital Data Transmission: Transmission Mode
Digital Data Transmission: Transmission Mode
Digital data uses discrete discontinuous signals to represent its meanings. In a DC (direct current) transmission system, different voltage (or current) values are used to represent the values (usually 0 and 1). A digital transmission has a very low error rate and can be sent at very high speeds. Weak signals can be regenerated with a low probability of cumulative error. Since all signals are made up of 0s and 1s, signals from many sources can be readily multiplexed using digital techniques. Let's discuss the modes of digital data transmission in detail.
Earlier Article: Digital Data Transmission
What is transmission mode?
Transmission mode means transferring of data between two devices. It is also called communication mode. These modes direct the direction of flow of information.
How can data transmission be categorized?
A given transmission on a communications channel between two machines can occur in several different ways. The transmission is characterised by:
- the direction of the exchanges
- the transmission mode: the number of bits sent simultaneously
- synchronization between the transmitter and receiver
How many types of Transmission Mode are there?
The Transmission Mode is used to define the direction of signal flow between two linked devices. There are three types of transmission modes characterized according to the direction of the exchanges: Simplex, Half-Duplex and Duplex.
Let's discuss the three types of Transmission mode.
Simplex
In Simplex mode, the data flows in only one direction (ie.. unidirectional) from the transmitter to the receiver. This type of connection is useful if the data do not need to flow in both directions. For example, Keyboards can only introduce input and printer can only receive the data.
Half-Duplex
In Half-Duplex mode, (sometimes called an alternating connection or semi-duplex) the data flows in one direction or the other, but not both at the same time.
This type of connection makes it possible to have bidirectional communications using the full capacity of the line. For example: Walkie Talkie. In this, the entire capacity of a channel is taken over by whichever of the two devices is transmitting at the time.
Full-Duplex
In Full-Duplex mode, the data flows in both directions simultaneously. Each end of the line can thus transmit and receive at the same time, which means that the bandwidth is divided in two for each direction of data transmission if the same transmission medium is used for both directions of transmission.
For example: Mobile Phones. In this, signals going in either direction share the capacity of the link wither by containing two separate physical links (one for sending and the other for receiving) or by dividing the capacity of the channel between signals travelling in opposite direction.
Well, that's it on transmission modes. We shall discuss Transmission Techniques in the next article, stay tuned for that.
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