Telecommunications channels make use of a variety of telecommunications media. These include twisted-pair wire, coaxial cables, and fiber-optical cables, all of which physically link the devices in a network. Also included are terrestrial microwave, communications satellites, cellular phone systems, and packed and LAN radio, all of which use microwave and other radio waves. In addition, there are infrared systems, which use infrared light to transmit and receive data.
Types of telecommunications Media
1) Wired Technologies
2) Wireless Technologies
Wired Technologies
Twisted-Pair wire
Ordinary telephone wire, consisting of copper wire twisted into pairs, is the most widely used medium for telecommunications. These lines are used in established communications networks throughout the world for both voice and data transmission. Twisted-pair wiring is wrapped or shielded in a variety of forms and used extensively in home and office telephone system and many local are networks and wide area network.
Coaxial cable
Coaxial cable consists of a sturdy copper or aluminum wire wrapped with spacers to insulate and protect it. The cable’s cover and insulation minimize interference and distortion of the signals the cable carries. Group of coaxial cables may be bundled together in a big cable for ease of installation. These high-quality lines can be placed underground and laid on the floors of lakes and oceans.
Fiber Optical
Fiber optical uses cables consisting of one or more hair-thin filaments of glass fiber wrapped in a protective jacket. They can conduct pulses of visible light elements generated by lasers at transmission rates as high as trillions of bits per second. This speed is hundreds of times faster than coaxial cable and thousands of times better than twisted-pair wire lines. Fiber-optic cables provide substantial size and thousand of time better than twisted-pair wire lines. Fiber-optical cables provides substantial size and weight reductions as well as increased speed and greater carrying capacity.
Wireless Technologies
Terrestrial Microwave
Terrestrial microwave involves earthbound microwave system that transmit high-speed radio signals in a line-of-sight path between relay stations space approximately 30 miles apart. Microwaves antennas are usually placed on top of buildings, towers, hills and mountain peaks, and they are a familiar sight in many section of country.
Communication Satellites
Communication Satellites also use microwaves radio as their telecommunications medium. Typically high-earth orbit (HEO) communication satellite are placed in stationary geosynchronous orbits approximately 22,000 miles above equator.
Satellite are powered by solar panels and can transmit microwave signals a rate of several 100 million per second.
Cellular and PCS Systems
Cellular and PCS telephones and pager system use several radio communications technologies. however, all of them divide geographic area into small areas, or cells, typically on from one to several square miles in area. Each cells has it’s own low-power transmitter or radio relay antenna device to relay calls one sale to another. computer and other communication processers coordinate and control the transmission to and from mobile user as they move from one area to another.
Wi-Fi
Wi-Fi is a way for wireless devices to communicate. Wi-Fi, short for wireless Fidelity, is the Wi-Fi Alliance’s name for a wireless standard, or protocol, used for wireless communication. Wiring an office or a building for a local area network is often a difficult and costly task. Older building frequently do not have coaxial cables or additional twisted-pair wire.
Bluetooth
A short range wireless technologies called Bluetooth is rapidly being build into computer and other device. Bluetooth serve as a cable-free wireless connection to peripheral device such as computer and scanner. Links up to 8 devices in 10-m area. Useful for personal networking (PANs) and in business to transmit data from handheld devices to other transmitters.
