What is transmission media?
Transmission media is a pathway through which data are transmitted in network. We use different types of cables or waves to transmit data.
What are the types of transmission media?
There are two types of transmission media namely: bound transmission media and unbound transmission media.
Describe bound transmission media.
Bound transmission media are the cables that are tangible or have physical existence and are limited by the physical geography. Popular bound transmission media in use are twisted pair cable, co-axial cable and fiber optical cable.
Describe unbound transmission media.
Unbound transmission media are the ways of transmitting data without using any cables. These media are not bounded by physical geography. Microwave, Radio wave, Infra red are some of popular unbound transmission media.
Explain twisted pair cable.
A pair of wires twisted with each other is known as twisted pair cable. A set of four pairs of twisted wires are bundled to form cable. These are the most common medium for LAN. Wires are twisted with each other so as to reduce the interference.
Explain Co-axial cable.
A solid central conductor surrounded by insulating material and then by a cylindrical shield woven from fine wires is known as co-axial cable. The shield is usually connected to electrical ground to reduce electrical interference. Co-axial cables have broader bandwidth and thus suitable for audio, video data transmission.
Explain Fiber-Optics cable.
A cable with central glass tube covered with protective shield which transmit data using photons is fiber optics cable. These cables transmit data via concentrated bursts of laser beams which are carried through bundles of hair thin glass fibers. They have advantages over electronic cables in transmission speed and volume. This technology has revolutionized telecommunication applications which used electronic cables. Fiber optics cables as free from electro- magnetic interference as well as wire tapping.
Unbound Transmission Media
Unbound transmission media extend beyond the limiting confines of cabling. They provide an excellent communication alternative for WANS. The lack of physical restrictions provides larger bandwidth as well as wide area capabilities. Unbound media typically operate at very high frequencies. The three types of unbound transmission media are: Radio wave, Micro wave, Infrared
Explain Radio Wave.
Although Radio waves are prevalent and well understood, we are just beginning to realize their enormous potential as a networking medium. Radio waves can operate on a single or multiple frequency bands.
What is Microwave?
Microwaves have been used in data communications for a long time. They have a higher frequency than radio waves and therefore can handle larger amounts of data.
Microwave transmission is line of sight transmission. The transmit station must be in visible contact with the receive station. This sets a limit on the distance between stations depending on the local geography. Typically the line of sight due to the Earth's curvature is only 50 km to the horizon! Repeater stations must be placed so the data signal can hop, skip and jump across the country.
List the Advantages of microwaves.
a. They require no right of way acquisition between towers.
b. They can carry high quantities of information due to their high operating frequencies.
c. Low cost land purchase: each tower occupies only a small area.
d. High frequency/short wavelength signals require small antennae.
What are the Disadvantages of Microwaves?
a. Attenuation by solid objects: birds, rain, snow and fog.
b. Reflected from flat surfaces like water and metal.
c. Diffracted (split) around solid objects.
d. Refracted by atmosphere, thus causing beam to be projected away from receiver.
Describe Infra Red.
Infrared offers a great unbound photonic solution. Like fiber-optic cabling, infrared communications use light, so they are not bound by the limitations of electricity.
0 comments:
Post a Comment