Data Communications : Components, Protocols Components


Data Communications : Components, protocols Components

 

Outcome : Audience will be able to
i.      differentiate between data and information

ii.      To name various components of a communication system

iii.      To describe the characteristics of the effective communication

iv.      To differentiate between protocol and standard

v.      To know various standards organization

 

Data

Data is considered to be raw data. It represents ‘values of qualitative or quantitative variables, belonging to a set of items.’ It may be in the form of numbers, letters, or a set of characters. Data is often collected via measurements. In data computing or data processing, data is represented by in a structure, such as tabular data, data tree, a data graph, etc.

Categories of Data

Data can be analog data or digital data- analog data refers to information that is continuous, example voice, surrounding temperature, time.

Digital data take discrete values, examples being the data stored in computer in the form of 0’s and 1’s. Digital clock displays the digital information about time.

Figure-1: Sound Waves

The simplest transmission of signal that we do every day is our voice transmission, but sound energy can travel only a small distance before it dies down. You can’t expect some one here your voice who is around 100 meter away or still little more than that. Also it is not possible for you listen to something that was said by someone a few days or years back.

All these are possible today. With the invention of microphone you could convert your voice energy into the electrical wave, then the invention of other devices such as telephone, computer etc it is possible today to communicate your signal (analog or digital) to far off place and also you could record somebody voice and listen to it at any time in future.

Thus, to communicate over longer distance we need to convert the data into signals. With the use of microphone we can convert your voice energy into the electrical wave called signals. At the other end these waves or signals are converted back into voice with the use of speakers. The use of mic and speakers covert our acoustic signal into electrical signals and then back into voice / audio. The audio signals can be stored as analog format or digital format for playing at a later time. Use of other communicating technology/devices have made it possible to transmit it to different networked systems.

Figure-3: Converting Sound to electrical and back to sound waves

Figure above shows how our voice is communicated using mic and speaker system. Voice, which is an acoustic wave is converted into electrical signal and transmitted over cables as electromagnetic signals and then again converted as the voice signal

Components of a computer communication:

 

In the today’s world you need a number of components made of both software and hardware to help you to communicate at a far off place. These are:

Figure-2: Components of Computer Communication (Source DCN by Forouzan, TMH)
  1. Message: The message is the information to be communicated. Popular for of information include text, numbers, pictures, audio, video.
  2. Sender- The sender is the device that sends the data message. It can be a computer, workstation, telephone, handset, video camera and so on
  3. Receiver- Is the device that receives the message. It can be a computer, workstation, telephone, handset, television etc.
  4. Transmission Medium – The transmission medium is a physical path by which a message travels from sender to the receiver. Some examples are twisted-pair wire, coaxial cable, fiber-optics cable, radio wave etc.
  5. Protocol – A protocol is a set of rule that govern data communication. It represents an agreement between the communicating devices. Without a protocol, two device may be connected but not communicating, just as a person speaking French cannot be understood by two persons speaking Hindi.

 

Characteristics of data communication:

 

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

I. 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 real-time transmission.

4. Jitter. Jitter refers to the variation in the packet arrival time. It is the uneven delay in the delivery of audio or video packets. For example, let us assume that video packets are sent every 3D ms. If some of the packets arrive with 3D-ms delay and others with 4D-ms delay, an uneven quality in the video is the result.

 

Difference between protocol and standards

 

Protocol : A protocol is a particular set of rules for having a conversation between two computers to convey a specific set of information. It is an agreement between the communicating parties on how the communication is to proceed. Violating the protocol will make the communication more difficult.

An example of protocol would be TCP/IP. The specifics of the above would detail the addressing format, number of bits used, methods to decide grouping, size of data chunks and more

 

Standard  : A standard (and in the networking arena, many protocols are standards) is a document that specifies something that has the overwhelming support and agreement of the standards making bodies.

An example of standards would be 802 standards. One of them, 802.3u, lays down the specifications related to FastEthernet. So, if anyone were to design a hardware or software related to FastEthernet, they would have to follow those specifications. Some of the standards making organizations are given below:

 

  • IEEE-Institute of Electrical, Electronics Engineers. Formed in 1962 by grouping Institute of Radio Engineers and American Institute of Electrical Engineers. Standards are designed and maintained by IEEE-SA (IEEE Standards Association)
  • ANSI- American National Standard Institute- five societies are AIEE, ASME, ASCE, AIME(mining), ASTM(testing & Material)
  • ITU-International telecommunication Union
  • ISO – International Organisation for standards
  • EIA – Electronic Industries Association
  • ESTI (Europian Telecommunications Standards Institute)-  ETSI has been successful in standardizing the Low Power Radio, Short Range Device, GSM cell phone system and the TETRA professional mobile radio system.
  • W3C-www consortium – formed on 18 Feb 2011

 

Questions:

 

Name the protocols and standards.

What are the components of data communication?

What are the characteristics of data networks?

What is the difference between standard and protocol, Name some standards and protocols.

 

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