Data communication medium
Some type of connection is required to exchange data between the receiving and sending computers. This connection is usually called a channel. The various methods used to implement channels are network media. Eg – common telephone lines, microwave systems, fibre optic cables, coaxial cables, satellite communication systems etc. The amount of data flow depends on the width of the channel. If the width of the channel is more, more data can be sent through it simultaneously.
Wired
Data can be exchanged between the sending and receiving computers through various types of cables. Namely--
(i) Co-axial cable (Co-axial cable)
(ii) Twisted pair cable
(iii) Fiber optic cable
(i) Co-axial cable:
A coaxial cable is a type of electrical conductor made of copper. This type of wire is made with the help of two electrically conductive and two electrically non-conductive materials. They have a white plastic insulator between them to cover the inner conductor and separate it from the outer conductor. A black plastic jacket is usually used to cover the outer conductor from the outside. The inner conductor copper wire is straight, but the outer conductor is twisted on all sides. Data transfer is very fast through such cables. But the data transfer rate depends on the distance. Data transfer speeds over coaxial cables can range from 10 Mbps to 2 Gbps. There are two types of coaxial cable. Namely: 1. Thinnet and 2. Thicknet
1. Thinnet: Thinnet coaxial cable is relatively thin. The cost of such cables is also low. There is no need to use a repeater up to 200 meters in sending data through thinnet.
2. Thicknet: Thicknet coaxial cable is thicker and weighs more than Thinnet. The price of this type of cable is higher than that of thinnet. There is no need to use a repeater up to 500 meters when sending data through a thicket. Signal loss is less in data transfer through such cables. The signal strength decreases as the distance increases during data transfer. Therefore repeaters have to be installed at certain distances. The function of the repeater is to increase the power of the signal through the amplifier circuit. Coaxial cables are used to transfer data from computers to monitors, to exchange data between multiple telephone exchanges in cable TV, and in local area networking.
(ii) Twisted pair cable: Both data and voice can be communicated through telephone lines. For this reason, this type of communication medium is widely used in almost all countries of the world. Twisted pair.
There are two types of cables. Namely-- (1) Unshielded Twisted Pair, (2) Shielded Twisted Pair.
Twisted pair cable is made by symmetrically twisting two conductors of copper. Twisted pair cable is very cheap in cost and easy to implement. Data transfer through such cables is affected by environmental temperature, humidity etc. Twisted pair cable is commonly used in local telephone systems. Used to protect connections between servers and terminals in some network systems. The data transfer speed is 9600 bps within a distance of 100 meters but the data transfer speed is lower for longer distances. There is a high probability of signal loss when data is transferred over such a medium. However, data can be sent over a distance of several kilometres without any amplification.
(iii) Fiber optic cable: Fiber optic cable is a type of cable made of glass fibres through which data is exchanged. Light signals instead of electrical signals. Many such cables are made using glass theory. A laser beam is used for data transfer through such cables. Plastic is usually used as a fibre jacket. Since light signals have a much higher frequency than electrical signals, data is transferred much faster through them. Fibre optic cables have data transfer speeds of 10 Mbps to 2 Gbps. Optical fibres consist of three segments. namely--
(1) Core,
(2) Cladding and
(3) Jacket.
Composition of fibres: Silica and glass are used as insulating materials for making fibres. The properties of these insulating materials are described below:
→ Energy wastage is reduced. Ultra clarity is chemical inertness. Easy processing capability. Fast data transfer capability.
The speed of data transfer through fibre optic cables is much higher than other mediums. The bandwidth of this type of cable is very high and the weight is relatively light. There is less chance of signal loss during data transfer. However, the cost of fibre optic cables is relatively high and the implementation of data transfer methods through such cables is relatively complicated. Fibre optic cables cannot be completely bent.
Communication System:
The transmitter collects data from the source and transmits it to the receiver through fibre optic cables. The data sent through the fibre is usually an analogue signal or a digital signal. After converting the digital signal into a light wave suitable for transport through the fibre with the necessary modulation, the transmitter injects it into the fibre. Optical fibres transport information by the total internal reflection of light rays. Thus the light beam is captured by the receiver through repeated total internal reflection. The data transfer speed of fibre optic cables is much higher than other cables. Fibre optic cable is generally used for fast data transfer over long distances. Three components are used for data transfer through fibre optic cables. namely-1. The light source, 2. medium and 3. detector.
This method uses LED (Light Emitting Diode) or Laser Diode as a light source. The function of an LED or Laser Diode is to convert electrical energy into light energy and transmit it through an optical fiber medium. That is, fibre optic cable is used as the medium here. A consumer device consists of two parts. These two are the photodetector and the processing unit. The job of the photo detector is to collect data from the fiber. The processing unit consists of an amplifier, filter, demodulator etc. They deliver the data to the user through proper demodulation, amplification and filtration. There are only two types of fiber optic. Namely:
(a) Single Mode Fiber Optic Cable: Light rays of only one wavelength are transmitted through it at a time.
(b) Multi-mode fiber optic cable: It transmits multiple light rays of different wavelengths simultaneously. is transported. Fiber is typically as thin as human hair and weighs less than other cables. Such cables are free from electromagnetic effects. Currently, data is being transferred through such mediums as telephone, mobile phones, internet.
Wireless Media: Wireless media can also be used for data exchange. namely--
(i) Radio wave
(ii) Microwave
(iii) Infrared
(i) Radio wave: The frequency of radio waves is usually from 10 KHz to 1 GHz. The electromagnetic spectrum between 10 KHz to 1 GHz is called radio frequency. There are three types of radio web. namely--
1. Low power frequency
2. High power frequency
3. Spread spectrum
1. Low Power Single Frequency: Low power single frequency radio waves operate only on a specific frequency.
2. High Power Single Frequency: High power single frequency radio waves can travel longer distances than low power frequencies and can penetrate any obstacles in the way. The distance can be increased by increasing the number of repeater stations.
3. Spread spectrum: In the spread spectrum, signals are sent over a range of frequencies instead of a single frequency. In this method, the signal is coded and sent. This ensures data security. The frequency range received from radio waves is divided into several parts.
(ii) Microwave System: A microwave system is used to send very high-frequency signals (2 GHz or more frequency) from one place to another through the air. Transmitter stations are placed every 25/30 km for data transfer to the surface through a microwave link. The signal transmitted from one transmitter station is amplified and amplified by the next station and transmitted to the next station. These stations are placed on top of buildings or on hilltops to avoid interference with signal transmission. Signals in microwave systems cannot follow curved paths. If the distance from the sending end to the receiving end is within 75 miles then two transmitter stations should be placed between them.
This system supports data transfer rates of 1Mbps—10Gbps and 250,000 simultaneous voice channels. Local telephone systems are generally used in large metropolitan areas. So if there is an obstacle between the sender and the receiver, the signal cannot be sent. Audio, video, image, text etc. can be sent from the computer in a microwave system.
Data transfer system using satellite: The main disadvantage of the microwave system is that the signal cannot travel in a curved path. So many repeaters are required for data transfer. Communication satellites act as relay stations for microwave systems. The satellites are 36000 km above the earth. The satellites rotate at the same speed as the Earth's rotation. Several satellites of various countries used for communication are currently floating in the void. A signal of 6 GHz frequency is transmitted along the satellite from the sending computer. After reaching the satellite, the strength of these signals is reduced. From the sending computer, these satellites receive the signal sent from the surface and amplify it and send it to the receiver at 4 GHz frequency. Sending thousands of miles away. Intelsat is an international satellite communications company. The member states of this organization are connected to each other through Intelsat satellites. Moreover, many countries have established their own satellite communication systems. Data is transferred from anywhere in India through INSAT-IB, India's own satellite. Communication satellites have data transfer speeds of 1Mbps to 10 Gbps.
(iii) Infrared (Infrared): Infrared is a type of electromagnetic wave whose speed is in the terahertz range. In this method LED (Light Emitting Diode) is used to transmit data and Photodiode is used in the receiver to receive. It cannot penetrate any solid material. Infrared signals lose their power when exposed to strong light sources.
Wireless Communication System:
The communication method that can exchange information over a certain distance without wires is called the wireless communication method. The distance between the computers used in this method can be short or long. It is used for networking in various types of fixed or mobile cellular phones, PDAs, and laptops. In those cases where it is difficult to establish communication using remote, wireless communication methods can easily establish communication.
Wireless Communication System Requirements: Following are the wireless communication system requirements:
(i) Wireless communication systems can be used in security systems in various residential buildings, and office buildings.
(ii) Cellular telephones use radio waves to make phone calls from different locations.
(iii) WiFi is a wireless local area network that connects various related hardware including computers to the Internet.
(iv) Currently various interfacing devices like keyboard, mouse etc. are using wireless technology.
(v) This technology is used in wireless remote control units of modern televisions.
Bluetooth
In 1994, telecom vendor Ericsson developed a wireless communication protocol called Bluetooth. Bluetooth is named after King Harald Bluetooth of Denmark. Bluetooth is a protocol used to exchange information between multiple computers located nearby in personal area network systems. It can be used to establish wireless networks. The distance between the computers used to exchange data through Bluetooth is from 10 to 100 meters. Currently personal computers laptops, PDAs, mobile phones etc. have Bluetooth built-in. Many users around the world are exchanging information easily through Bluetooth. The speed of data exchange through this is 1 Mbps Bluetooth works at 2.4 GHz frequency. The network established through Bluetooth technology is called Piconet. Multiple piconets together are called scatter nets. Each piconet can have one master node and up to seven slave nodes. Below is a diagram of a scatternet consisting of two piconets:
Bluetooth is used to transfer data between multiple devices located in close proximity using radio waves. Data can be exchanged over wireless communication systems without any license. Walls or other barriers cannot impede data exchange. The Bluetooth Special Interest Group works to manage Bluetooth. Its membership is 15 thousand companies. Among them are telecommunication, computing, and networking companies. Bluetooth can transmit data at 2.4GHz frequency. Bluetooth can be used to exchange data between faxes, mobiles, telephones, laptops, Global Positioning System (GPS) receivers, digital cameras, etc. It is easily portable and can automatically detect different devices.
WiFi
WiFi is a wireless LAN standard whose main purpose is to easily connect portable computing devices to the Internet. WiFi is derived from two words Wireless Fidelity. This method uses a high-power transmitter which achieves 2.5 hops per second. WiFi can be connected to PCs, video games, smartphones, etc. Currently, more than 900 million people are using WiFi. The Internet connection can be easily found in places where the internet network is not usually available like the kitchen or garden.
Range
WiFi is limited to a small area. A typical wireless access point uses 802.11b or 802.11g to provide connectivity up to 32 meters (120 ft) indoors and up to 95 meters (300 ft) outdoors. The range also depends on the frequency band. The 2.4 frequency can cover a slightly larger area than the 5 GHz frequency.
WiFi LAN can be used in public places such as libraries, hotels, railway stations, airports, and cafeterias. In some places, such as open areas or historical places, it is easier to create a LAN. Through this, multiple devices can be connected to the internet at the same time. Most laptops and smartphones have built-in wireless adapters, so it's very cost-effective to use. It can be used anywhere in the world as it is considered the same standard. Networking through it does not require any authority approval. Data transfer speed over WiFi is average. Sometimes the connection is disconnected. Also, transferring data to multiple devices simultaneously can cause signal jams.
WiMax
WiMax Worldwide Interoperability for Microwave Access | WiMax is a type of wireless communication system used for Internet connectivity over a large area. In 2005 its speed was 40 Mbit/s but in 2011 its speed stagnated. Gbit/s. WiMax is a part of the 4th generation of wireless technology In the case of a local area network, this connection is spread over 30 meters (100 feet) and in case of a metropolitan area network, 50 kilometres (30 miles). Data transfer speed within Wimax ranges from 30 Mbps to 40 Mbps.
Users new to WiMax can get faster connections. Its receiver is easily portable. A base station can be used by more than a hundred users. 10 Mbps speed is available within 10 km. However, an uninterrupted signal is not available in bad weather. Data exchange consumes more power. It is high in expensive maintenance cost. Bandwidth decreases if the number of users in the same area is high. Through this, a wireless internet facility is available instead of wired internet.
Comments
Post a Comment