Data Transmission Modes

Data Transmission Modes

There are three ways for transmitting data from one point to another -

1.Simplex: In simplex mode the communication can take place in one direction. The receiver receives the signal from the transmitting device. In this mode the flow of information is Uni.-directional. Hence it is rarely used for data communication.

2.Half-duplex: In half-duplex mode the communication channel is used in both directions, but only in one direction at a time. Thus a half-duplex line can alternately send and receive data.

3.Full-duplex: In full duplex the communication channel is used in both directions at the same time. Use of full-duplex line improves the efficiency as the line turn-around time required in half-duplex arrangement is eliminated. Example of this mode of transmission is the telephone line.

Types Of Data Transmission

Types Of Data Transmission

There are two types of data transmission in computers they are - 

1. Analog Transmission.
2. Digital Transmission.

1. Analog Transmission :- Analog signals can travel longer distances. It is easy to convert the digital signal into an analog equivalent and send it to long distances. This method is called Modulation. At the receiving end the digital form of 0 or 1 can be recovered from the analog signals. This method of retrieval is called demodulation. This approach seems to be simple but there is a limitation in it. These signals are highly disturbed by electric fluctuations. Noise in electric parlance mixes with the analog signal and disturbs it. 

2. Digital Transmission :- The digital signals are less error prone. These signals cannot travel longer distances like the analog signals. A booster is required to do so. The digital signals are absorbed and regenerated at regular intervals and in this way noise signals are eliminated. The digital transmission is preferred to analog transmission due to its high quality.

Communication Protocols

Communication Protocols

You may be wondering how do the computers send and receive data across communication links. The answer is data communication software. It is this software that enables us to communicate with other systems. The data communication software instructs computer systems and devices as to how exactly data is to be transferred from one place to another. The procedure of data transformation in the form of software is commonly called protocol.

The data transmission software or protocols perform the following functions for the efficient and error free transmission of data.

1. Data sequencing: A long message to be transmitted is broken into smaller packets of fixed size for error free data transmission.
2. Data Routing: It is the process of finding the most efficient route between source and destination before sending the data.
3. Flow control: All machines are not equally efficient in terms of speed. Hence the flow control regulates the process of sending data between fast sender and slow receiver.
4. Error Control: Error detecting and recovering is the one of the main function of communication software. It ensures that data are transmitted without any error.