Concept of Communication System
Communication is an innate process. Not only humans but animals as well. One interacts with the other. Since the dawn of human civilization, human beings have communicated with each other in various ways to meet various needs. This is why they first use gestures or gestures, later use their own sign language. In the aftermath of the rise of civilization, letters were sent in person to communicate with distant caravans, and later. The communication process starts with the post office, trunk calls, telegraph, or telephone. Radio, TV, etc. are also a type of communication process or medium through which a presenter or news reader
It is able to communicate by delivering information to a large number of viewers. Such exchanges or communication system is the process by which one communicates with another to exchange information. In today's world, with the advent of the Internet, or the mobile phone, the scope of the communication process has become wider, wider, and easier, and now not only people with humans, but also devices with devices. So we can say that communication is a process of exchanging information between different people or devices to achieve a goal or purpose in a well-coordinated manner. It is used to transmit information or messages verbally or anywhere else through the sender, receiver, communication, and some devices.
Concept of Data Communication
Data communication or data communication is done to make the communication effective. It is a system for secure and efficient data exchange between the source (sender) and the receiver. Figure 2.1 shows the structure of an electronic data communication system. And the receiver is required. The transmitter first converts the data from CERS into the medium by converting it into an electric or electric signal. The receiver then receives the signal or data from the medium and delivers it to the destination. (Data is also corrected in case of data distortion due to unexpected noise or other reasons.) Examples of different communication elements:
1. Sears: Camera, microphone, computer keyboard, etc.
2. Transmitter: Modem, Router, TV Station, Radio Station, Telephone & Mobile Phone. Company Exchange etc.
3. Medium: telephone line, fiber optic cable, microwave, etc.
4. Receiver: modem, router, telephone exchange, etc.
5. Destination: computer, server, telephone or mobile phone, etc.
In today's world, we all have more or less Internet Table 2.1; Different services have an idea about the required bandwidth and its speed. The speed of this internet.
Email Up to 0.5 Mbps bandwidth. That every second. Web browsing
0.5 to 1.0 amount of data transferred from one place to another
Mbps Streaming music
0.5 Mbps is the bandwidth of the data transfer rate. Says. Bandwidth is usually a bit per second (bps).
Phone Call (VoIP)
Calculated at 0.5 Mbps. But lately, there is a lot in the network Streaming video
0.7 Mbps more bandwidth available bps (bps) - Streaming movie
Kbps instead of 1.5 Mbps (one: per second streaming HD movie)
4 Mbps thousand bits) or Mbps (Mbps; per second video conferencing)
1 Mbps One Million Bit) Even Gbps (Gbps: Video Conferencing HD)
4 Mbps one second bit per second) much more Internet also a game console
1 Mbps is used. Eight bits is called one byte Online HD multiplayer gaming 4 Mbps is one MBps to eight Mbps. The bandwidth of a communication network depends on the equipment and medium used there. Fiber optic cable has many times more bandwidth than ordinary telephone cables. Again, with fiber optic cable, if the appropriate speed terminal equipment is not used, it is not possible to get the required bandwidth. Since many people use a communication network, the bandwidth of the network is shared among all users. Many times a user or a service occupies a large portion of the bandwidth and reduces the share of others. There are a variety of ways to measure how much actual bandwidth a user is receiving on a network, depending on the design of the network or the equipment.
If there is a problem in the corner, it is possible to find out. That's why bandwidth management is a big challenge right now. Table 2.1 lists the bandwidth required for various services. Therefore, if a user does not have the required bandwidth for a particular service, then it is not possible for him to receive that service properly.
Data Transmission Method
In data communication, the process of transferring data from one device to another through the format of data bits is called the data transmission method. The data transmission method is divided into parallel data transmission and serial data transmission based on bit format. In serial data transmission, one bit is sent at a time through one medium. In parallel data transmission, many bits are sent at once through numerous means. Parallel data transmission.
Parallel data transmission also has one or two control lines to coordinate the sender and receiver devices with many data lines for simultaneous data transmission. The bits are moved simultaneously at exactly the same time. Since the data in the internal circuit of the computer work in parallel mode, its normal format is in parallel data transmission. It is a very fast transmission as data is sent on numerous lines simultaneously. However, it is not realistic to send data far away. This two-pronged method is often used in video streaming. Also, the use of parallel printer parts and cables to connect the printer to the computer, etc. are examples.
Serial data transmission
In this transmission, one bit after another is continuously transferred between the sender and the recipient located at any distance. This is a reliable method because it transmits the previous data bit after the other. The equipment is relatively simple and affordable as only one is used. Besides, the effect of noise is less because there are not many of them. The USB (USB: Universal Serial Bus) portion that is seen on computers and almost all devices today is an example of serial transmission.
When transmitting data in serial mode, both the sender and the receiver devices have to use the clock and one bit is sent and received per pulse per hour. Using this clock, a special method is used to determine the beginning and end of a bit, called bit synchronization. Due to bit synchronization, the data from the received signal can be detected and retrieved.
1. Asynchronous Transmission
2. Synchronous Transmission and
3. Isochronous transmission
Asynchronous transmissions can send data whenever the sender is happy, the customer is always ready to receive that data. Not only this, with the help of data sending you can take as much time as you want in the middle of sending data again. Send a start bit before sending data, Yes and by looking at that bit the customer understands that the data has started coming in and his clock adjusts to the beginning of that bit. After the data is sent, a stop bit is sent and the customer sees it. The device realizes that the data has been sent. Primary storage devices (RAM, cache, or CPU memory used in the computer, etc.) are not required in this case as data can be transmitted when needed. This method is convenient for sending small amounts of data at low speeds. An example of an asynchronous transmission is a computer keyboard. Press a key here The interval between typing by pressing the next key is bound to be unequal or indefinite. This is why this transmission system is called asynchronous.
Synchronous data transmission is called uninterrupted data transmission. In this method, data is transmitted continuously from the transmitter to the receiver. Since the receiving device adjusts its clock using the transmitted data, the predefined data is sent as idle sequence even if there is no data to be transmitted. The synchronous data transmission method first sends the data to the sender station in the primary storage (RAM, cache, or CPU memory used in the computer, etc.) and divides the data characters into blocks or frames. Equal breaks by adjusting with one block or frame clock each time
Is transmitted with. Header information of 1 or 2 bytes is sent at the beginning of each block-data and a trailer information signal of the same size is sent at the end of the block-data and usually, the identification number or address is usually given to the sender and customer to find the destination in the huge network. The receiver uses this header signal to synchronize with the sender's clock speed. The trailer indicates the end of the block and in any case, helps to diagnose and correct errors inside the block. Although technically this method is relatively complex and expensive, it is widely used for transmitting high bandwidth data over long distances. So it is essential in the case of the mobile phone network, T, V, network, etc. with a large network.
A combination of asynchronous and asynchronous is the isochronous transmission. In this process, data is transferred in the form of blocks between the start and stop bits of the asynchronous system in a synchronous manner. Since it is not completely synchronous, the data can be transmitted when needed without storing it on a storage device. It is more common in real-time applications. In the case of various multimedia communications, such as audio or video calls, data transmission is used in this manner.
Data Transmission Mode
Data transmission is a data communication interface that directs the flow of information or data between two devices. Depending on the direction of data flow, the data transmission line is divided into three parts.
This method can only send data to one side. Yes, the sender just sends the data, and the subscriber Just accepts data. Key Bird, Mouse, Pager Simplex Made Examples. Half-duplex mode: In this way, data can be sent or received by both parties, but not together, separately. When one device sends data, the other has to wait for the opportunity to come. In this method, special circuits have to be arranged to prevent collision inside the data. Waikiki, Fax, S, M, S, etc. run in half-duplex mode.
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