A path through which info is transmitted in one place to another is called communication channel. It is additionally termed as communication medium or link. The twisted pair wire, coaxial cable, fiber optic cable, microwave, satellite etc. are instances of communication channels.
In a communication channel, information is transmitted in the form of signals (analog signal). The data transmission is measured in bandwidth. The bandwidth is going to be higher if more signals can be transmitted. Actually, the bandwidth measures the quantity of information that can be transmitted from the media within the given period of time. For analog signals, bandwidth is represented in hertz (Hz). It means variety of signals transmitted per second. For digital signals, it is represented in bits per second (bps). Different transmission media have different bandwidths. The higher the bandwidth from the transmission media, the more information can be transmitted.
Types of Communication Channel:
The communication channel or media is divided into two types.
In guided communication media, communication products are directly related to the other via cables or physical media for transmission of knowledge. The data signals are bounded to a cabling media. Therefore, guided media can also be called bounded media. The guided media are often utilized in LAN. The samples of guided or bounded media are:
Twisted Pair Cable: Twisted pair cable is one from the mostly used communication media.
It is employed in local area network (LAN) for data communication between different computers. It can also be used in telephone lines to carry voice and data signals.
A twisted pair cable has a set of two thin diameter copper wires. These wires are covered by padding (including plastic). These set of two wires are twisted together to make a cable. The wires are twisted around one another to attenuate (or reduce) interference using their company twisted pairs inside the cable. I know Firewire 800 9 Pin cable some pretty interesting stuff?
The data transmission speed through twisted pair cable is around 9600 bits per second in the distance of 100 meters. However, this transmission speed is less than coaxial cable or optical fiber.
The twisted pair cable may be the common communication channel for voice and data communication. But now its use is reducing because today more reliable communication media can be purchased including coaxial cable, fiber optic cable microwave and satellite.
Coaxial Cable: Coaxial cable can be termed as Coax. It carries signals of upper frequency ranges than twisted-pair cable. Coaxial cable is made up of single solid copper wire, called the inner conductor.
Coaxial cable may be used for telephone lines for voice and data transmission with quite high frequency. The bandwidth of coaxial cable is 80 times in excess of that relating to twisted pair media. Coaxial cable is additionally widely used in local area network (LAN). It is higher priced than twisted-pair wire.
Fiber-Optic Cable: In twisted-pair cable and coaxial cable, details are transmitted in the form of electric frequencies. The fiber optic cable uses light for you data. The data transmission speed is extremely high (because fiber-optic cable uses light to deliver data). The data transmission speed is up to billions bits per second. Today, most with the telephone companies and cable TV operators are choosing fiber optic cables within their networks.
A fiber optic cable includes tubes of glass (or thin glass fibers) by which information is transmitted as pulses of light. A typical optical fiber includes a very narrow strand or fiber of glass called the core. It is thinner than the usual natural splendor. The core is encompassed by a concentric layer of glass called Cladding. The diameter of a core is 62.5 microns (I micron = 10-6 meters). The diameter of cladding is around 125 microns. The cladding is coated with insulating material like plastic, called the Jacket.
2. Unguided Media:
In unguided communication media, info is communicated between communication devices available as wave. Unguided media provides means to deliver data signals but does not guide them along a unique path. The data signals are certainly not bounded to some cabling media. Therefore,. unguided media can be called unbounded media.
This transmission medium is employed when it is impossible to install the cables. The data could be transmitted worldwide through this medium. The examples of unguided or unbounded media are:
Microwaves: In microwave transmission, info is transmitted through air or space, rather than through cables or wires. Microwaves are high frequency radio waves. These waves is only able to travel in straight lines.
The info is transmitted and received through a microwave station. A microwave station can be called relay station or booster. A microwave station contains an antenna, transmitter, receiver, and other equipments which might be essential for microwave transmission. Microwave antennas they fit for the high towers or buildings and these are put within 20 to 30 miles of each other. There may be many microwave stations relating to the sender and receiver. Data is transmitted from one microwave station to a new. Each microwave station receives signals from previous microwave station and transmits to next station. In this way, info is transmitted over larger distances.
The data transmission speed of microwave transmission can be 150 Mbps. Microwave transmission is used in environments where installing physical transmission media doesn’t seem possible and where line-of-sight transmission is accessible, it is used in wide-open areas. Today, it’s employed by telephone companies, wire providers, universities etc.
Satellite Communication: A communication satellite is really a space station. It receives microwave signals (or messages) from earth stations. Satellite transmission station that may send and receive messages is recognized as earth station. The earth based stations often are microwave stations. Other devices, such as PDAs and GPS receivers, also functions as earth based stations.
Satellites rotate approximately 22,300 miles over the earth in precise locations. The communication satellite includes solar powered, transceiver that receives and sends signals. The signals are transmitted in one earth station on the satellite. The satellite receives and amplifies the signals and sends them to another earth station. This entire process takes only a few seconds. In this way, data or messages are transferred from location to a different. Transmitting a transmission from ground or earth station to a satellite station in space is named up-linking as well as the reverse is called the down-linking. The data transmission speed of communication satellite is high like upto 1 Gbps.
Different communication satellites are used to hold different types of information such as calls, television transmissions, military communication, weather data, as well as stereo utilize them for broadcasting. The global positioning systems and Internet also have the communication satellites.
Radio Broadcast: It can be a wireless transmission medium that is utilized to speak information through radio signals in air, over long-distance like between cities and countries.
In this medium, a transmitter is needed to send messages (signals) and receiver is necessary to receive them. To receive the radio signal, the receiver comes with an antenna that is located within the variety of signal. Some networks utilize a special device called transceiver utilized to send also to receive messages in the form of radio signals. The data transmission speed of radio broadcast can be 54 Mbps.
Cellular Radio: Cellular radio is really a way of radio broadcast that is employed for mobile communications including cellular telephones and wireless modems. A cellular, telephone is a telephone device that uses high frequency radio waves to transmit voice and digital messages. Some mobile users connect their laptop computer and other cellular devices to a cellular telephone gain access to the Web, send and receive e-mail etc. while from an ordinary line.