Components and Basic Block Diagram of Data Communication

Basic Components of data communication are:

Components and Basic Block Diagram of Data Communication


  • Source: It is the transmitter of data.

Examples are Terminal, Computer, Mainframe, etc.

  • Medium: The communications stream through which the data is being transmitted.

Examples are Cabling, Microwave, Fiber optics, Radio Frequencies (RF), Infrared Wireless, etc.

  • Receiver: The receiver of the data transmitted.

Examples are Printer, Terminal, Mainframe, and Computer.

Components and Basic Block Diagram of Data Communication
Components and Basic Block Diagram of Data Communication

The above figure shows the basic block diagram of a typical data communication system. This can further be broken down into three; the source system, transmission system, and destination system.

1. Source


The source generates the information or data that will be transmitted to the destination. Popular forms of information include text, numbers, pictures, audio, video, or a combination of any of these.

Information is put together in analog or digital form and broken into a group or segment of data called packets. Each packet consists of the following:

  • the actual data being sent
  • header
  • information about the type of data
  • where the data came from
  • where it is going, and
  • how it should be reassembled so the message is clear and in order when it arrives at the destination.

2. Transmitter


The transmitter a device used to convert the data as per the destination requirement.

For example, a modem converts the analog (telephonic) signal to digital (computer) signals and alternatively digital to analog.

3. Transmission medium


The transmission medium is the physical path by which data travels from the transmitter to the receiver.

For Example of such channels are copper wires, optical fibers, and wireless communication channels, etc.

4. Receiver


This receives the signals from the transmission medium and converts it into a form that is suitable to the destination device.

For example, a modem accepts an analog signal from a transmission channel and transforms it into digital bitstream which is acceptable by the computer system.

5. Destination


It is simply a device for which source device sends the data.

Data Communication Criteria


The effectiveness of the data communications system depends on four fundamental characteristics:

1. Delivery

The system must deliver data to the correct destination. Data must be received by the intended device or user and only by that device or user.

2. Accuracy

The system must deliver the data accurately. Data that have been altered in transmission and left uncorrected are unusable.

3. Timeliness

The system must deliver data in a timely manner. Data delivered late are useless. In the case of video and audio, timely delivery means delivering data as they are produced, in the same order that they are produced, and without significant delay. This kind of delivery is called a real-time transmission and this occurs in a real-time system.

4. Jitter

Jitter refers to the variation in the packet arrival time. It is an uneven delay of the delivery of audio or video packets.

For example, let us assume that video packets are sent every 20ms. If some of the packets arrive with a 20ms delay and others with a 30ms delay, an uneven quality in the video is the result.


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