Let us first know the brief introduction to the data communication. As we know the term communication represents the transfer of data between the two devices either from sender to receiver or receiver to sender. Similar to this, data communication defines as the electronic transmission of information or data.
The exchange of information or between the sender to receiver or receiver to the sender is called data communication. The data can be transmitted through a medium called the transmission medium. The transmission medium can be wired cable or wireless cable. The form of the transmission medium can be wired or wireless devices. The data communication system also be of different types. It is mainly made up of the five basic components. There are
- Transmission medium
The above five categories are the most basic in data communication. Let us know each type of category in detail. The below figure 1.1 represents the components that are present in the data communication. The sender sends the data or information through the medium to the receiver.
The sender and receiver should follow some set of rules, the set of all these rules we call the protocols. When the receiver wants to receive the data, then the user must follow some set of rules. The transmitted message can be any type of data, it may be voice, video, file, image, or document and we can also send audio or video message in the form of wireless signals. The medium can be a physical path from where the message travels from one device to the other device.
The rules we use for sending and receiving of the data from the device to device, we use some set of protocols, these protocols define how and what data is communicated between the devices, the protocols also consist of some of the key elements, the key elements define the structure of the protocol.
Syntax, semantics, and timing are the elements that are present in the protocol. The syntax is used to read the bits properly and the semantic element is used to interpret the meaning of the bit, the semantics also defines the function of each field. The last component in semantic is called timing.
The Timing defines what data to send and the data we should speed up the transmission. Bit what actually the difference between the protocol and the standard in the data communication? The standard can provide the guidelines for the service providers.
The standard ensures the interconnectivity for international communications. We also have different categories of standards. There are actually two types called, De facto and De jure. Let us know the Defacto represents by fact or by the convention and De jure represents by law or by a government.
We have different standards for the data organizations. One of the organizations is ISO. ISO stands for international standard organization. The ISO also follows some of the standards called ITU-T(International Telecommunication Union), IEEE(Institute of electrical and electronic engineering), and ANSI(American national standard institutional). Let study the wireless signals.
The information through a wireless signal is passed in the form of the signal when we transfer the data, the data is transferred in the form of the electrical signal, the data should be converted into the electromagnetic form, these electromagnetic signals can be in the form of analog signals or digital signals.
The analog signal may be in the form of voice and digital signals may be in the form of files and documents. Let us understand the clear view of digital and analog signals. The digital signal can represent the sequence of voltage paths. These are mostly used within the circuit computer system. The analog signal is in continuous form and can be represented by the sequence of electromagnetic waves.
But when we want to transmit the data from one medium to another medium, the transferred information can differ from the signal received to the user. Due to some of the disturbance from the receiver side, the data cannot be reached correctly. For a better understanding let us take an example, when we take via a telephone signal, the data can be varied when it comes to the receiver side, the words we speak may be heard differently by the receiver.
This type of disturbance we call the transmission impairment. The transmission impairment may occur at any type of transmission. The different consequences can take place at different signals like analog and digital signals.
In analog signals, the degradation of the data may occur, i.e the signal quality may decrease when it comes to the receiver. In the digital signal, the data is transmitted in the form of 0’s and 1’s. During transmission, when the data changes from 0 to 1 or 1 to 0. These changes we call the bit error. Let us study the concept of digital data transmission in detail.
The data transmission can be divided into two types. There is serial and parallel communication. Serial data communication can be divided into two types. It can be synchronous and in asynchronous form. In the serial transmission, the data can be transferred one by one in a serial manner. But in the parallel transmission, the data can be sent together, all the data will be sent together from the sender to the receiver.
The data can be in synchronous and asynchronous form. In the synchronous transmission, the data can be sent in the form of bits one after another. The user will group all the bits together. When the receiver receives the message from the sender, the receiver counts the no of bits it arrived and will group all types of bits in it.
The below figure 1.1 represents the synchronous form of data transmission, the transmission of the data cannot be stopped in the middle until it received by the receiver side. In the asynchronous transmission, we should send extra start and end bits at the beginning and end of the data. The below figure 1.2 represents the data asynchronous data transfer. The start and end bits may help the receiver to understand separate data. In order to transmit the signal in the form of digital, the data must be converted into digital form. The digital to digital data transmission is to convert the digital data into the form of digital signals.
The conversion of the digital signal can be of two ways. Line coding and another one is block coding. Let us know two different types of coding in detail. The conversion of digital data into the form of digital coding is called line coding.
The digital data can be represented in the form of both binary format and the digital signal is in the form of a digital signal. the below 1.3 figure represents the line coding. The data that is sent by the sender transmits in the form of the digital signal, the encoder converts this digital data in the form of digital signals and at the receiver side, the decoder will decode the data and again it converted into the form of signals.
we also have different types the line codings like unipolar, bipolar, and polar. The unipolar will represent the level of the single voltage, the digit one represents high voltage, and digit 0 represents the low voltage. The next is called as polar encoding, in the polar encoding we use multi-voltage levels to represent the binary values. The DTE is used to transfer the information either on the sender side or on the receiver side. The DTE stands for Data terminal equipment.
The DTE can act as a terminal, printer, computer or it can be any kind of device. The data terminal equipment can generate and consume the digital form of the data. The DTE cannot communicate directly with each other. The other is called DCE, the DCE stands for data circuit terminating equipment. The DCE is also a device that can transmit the data in the form of an analog and digital signal, modulator and demodulator are the best examples for the DCE device.
To make a communication between the two devices, it must use the same modulation method it. we also have many of the standards for the DCE and DTE. Each standard provides different types of functions and characteristics. There are some of the EIA and ITU-T. These two act as the most active standards and helps in developing the DTE-DCE interface standards. We can measure all these transmitting performances through propagation and throughput.
The throughput defines how fast the data can be passed from one device to the other device, it can define the number of the passing signals through a single wall or a medium. we also have the propagation speed, where the signal can travel in a single second, the propagation speed mostly depends on two types like medium and frequency of the signal and the propagation time can define the time taken by the signal to travel one point to another point in a medium.
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