A path through which facts are transmitted derived from one of destination to amazing . 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, data is transmitted as signals (analog signal). The data transmission is measured in bandwidth. The bandwidth will probably be higher if more signals might be transmitted. Actually, the bandwidth measures the volume of information that can be transmitted over the media inside the given time frame. For analog signals, bandwidth is represented in hertz (Hz). It means number of signals transmitted per second. For digital signals, it’s represented in bits per second (bps). Different transmission media have different bandwidths. The higher the bandwidth with the transmission media, the greater information could be transmitted.
Types of Communication Channel:
The communication channel or media is divided into two sorts.
In guided communication media, communication items are directly related to the other person via cables or physical media for transmission of information. The data signals are bounded to a cabling media. Therefore, guided media is also called bounded media. The guided media are usually used in LAN. The instances of guided or bounded media are:
Twisted Pair Cable: Twisted pair cable is one in the most commonly used communication media.
It is found in local area network (LAN) for data communication between different computers. It can be utilized in telephone lines to handle voice and data signals.
A twisted pair cable includes a pair of thin diameter copper wires. These wires are handled by padding (for example plastic). These couple of wires are twisted together to make a cable. The wires are twisted around each other to reduce (or reduce) interference from other twisted pairs within the cable. Where can I buy can’t believe this but later you second guessed yourself?
The data transmission speed through twisted pair cable is all about 9600 bits per second in a very distance of 100 meters. However, this transmission speed is lower than coaxial cable or optical fiber.
The twisted pair cable may be the conventional communication channel for voice and data communication. But now its use is reducing because today more reliable communication media can be obtained such as coaxial cable, fiber optic cable microwave and satellite.
Coaxial Cable: Coaxial cable is additionally referred to as Coax. It carries signals better frequency ranges than twisted-pair cable. Coaxial cable includes a single solid copper wire, which is called the inner conductor.
Coaxial cable could be used for telephone lines for voice and data transmission with extremely high frequency. The bandwidth of coaxial cable is 80 times more than that relating to twisted pair media. Coaxial cable can be widely employed in local area network (LAN). It is costlier than twisted-pair wire.
Fiber-Optic Cable: In twisted-pair cable and coaxial cable, info is transmitted as electric frequencies. The fiber optic cable uses light for you data. The data transmission speed is very high (because fiber-optic cable uses light to deliver data). The data transmission speed is about billions bits per second. Today, most of the telephone companies and cable TV operators are employing fiber optic cables inside their networks.
A fiber optic cable is made up of tubes of glass (or thin glass fibers) in which info is transmitted as pulses of light. A typical optical fiber consists of a very narrow strand or fiber of glass referred to as core. It is thinner than a real hair. The core is in the middle of a concentric layer of glass called Cladding. The diameter of the core is 62.5 microns (I micron = 10-6 meters). The diameter of cladding is approximately 125 microns. The cladding is coated with heat retaining material for example plastic, called the Jacket.
2. Unguided Media:
In unguided communication media, details are communicated between communication devices as wave. Unguided media provides means for you data signals but doesn’t guide them along a certain path. The data signals are certainly not bounded to your cabling media. Therefore,. unguided media can also be called unbounded media.
This transmission medium is utilized when it can be impossible to install the cables. The data might be transmitted all over the world through this medium. The types of unguided or unbounded media are:
Microwaves: In microwave transmission, data is transmitted through air or space, instead of through cables or wires. Microwaves are high frequency radio waves. These waves can only travel in straight lines.
The info is transmitted and received via a microwave station. A microwave station can be called relay station or booster. A microwave station contains an antenna, transmitter, receiver, along with other equipments which can be needed for microwave transmission. Microwave antennas are placed on the high towers or buildings that they fit within 20 to 30 miles of one another. There may be many microwave stations between the sender and receiver. Data is transmitted in one microwave station to another. 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 is about 150 Mbps. Microwave transmission is used in environments where installing physical transmission media is impossible and where line-of-sight transmission is available, it really is utilized in wide-open areas. Today, it is used by telephone companies, cable providers, universities etc.
Satellite Communication: A communication satellite can be a space station. It receives microwave signals (or messages) from earth stations. Satellite transmission station that could send and receive messages is recognized as earth station. The earth based stations often are microwave stations. Other devices, including PDAs and GPS receivers, also functions as earth based stations.
Satellites rotate approximately 22,300 miles higher than the earth in precise locations. The communication satellite is made up of solar powered, transceiver that receives and sends signals. The signals are transmitted from earth station for the satellite. The satellite receives and amplifies the signals and sends them to a new earth station. This entire process takes just a few seconds. In this way, data or messages are transferred from location to a new. Transmitting an indication from ground or earth station with 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 extremely high for example upto 1 Gbps.
Different communication satellites are used to hold kinds of information such as cell phone calls, television transmissions, military communication, weather data, and in many cases radio stations use them commercially broadcasting. The global positioning systems and Internet also have the communication satellites.
Radio Broadcast: It is really a wireless transmission medium that is used to convey information through radio signals in air, over cross country such as between cities and countries.
In this medium, a transmitter is required to send messages (signals) and receiver is necessary to receive them. To receive the air signal, the receiver comes with an antenna which is located inside array of signal. Some networks make use of a special device called transceiver utilized to send and receive messages by means of radio signals. The data transmission speed of radio broadcast is perfectly up to 54 Mbps.
Cellular Radio: Cellular radio is a type of radio broadcast that is utilized for mobile communications such as cellular telephones and wireless modems. A cellular, telephone is a telephone device that uses high frequency radio waves to deliver voice and digital messages. Some mobile users connect their laptop computer and other mobile phones with a cellular telephone to gain access to the Web, send and receive e-mail etc. while from an ordinary telephone line.