Computer Engineering Articles - Page 33 of 35

In fiber optic communication, signals are transmitted through an optical fiber. This is based upon certain characteristics of light, namely refraction and total internal reflection.RefractionWhen a light ray goes from a denser transmission medium to a rarer one or vice versa, then its direction changes at the interface of the two medium. This phenomenon is called refraction of light.The density of an optical medium is measured in refractive index. Higher the refractive index, denser it is.The angle between the incident ray and the normal is called angle of incidence Θi, while the angle between the refracted ray and the normal ... Read More

In fiber optic communication, data is transmitted from the source to the destination by sending light pulses through optical fibers. It changes electrical pulses to light signals and vice versa for communication. Fiber optic communications are preferred when a huge amount of data needs to be transmitted across large distances.The process of communication using fiber optics has the following steps −Conversion of input electrical data to light signals : The data to be sent by the sender is in the form of electrical signals. These signals are converted to light pulses by the transmitter circuitry using a light source. A ... Read More

Coaxial cables, commonly called coax, are copper cables with metal shielding designed to provide immunity against noise and greater bandwidth. Coax can transmit signals over larger distances at a higher speed as compared to twisted pair cables.Structure of Coaxial CablesCoax has a central core of stiff copper conductor for transmitting signals.  This is covered by an insulating material. The insulator is encased by a closely woven braided metal outer conductor that acts as a shield against noise. The outer conductor is again enclosed by a plastic insulating cover. The structure is shown in the following figure −Categories of Coaxial CablesCoaxial ... Read More

The primary purpose of computer networks is to transfer data from a source machine to a destination machine. One of the elementary ways to transfer data between machines is to use removable storage media. The steps for the transfer are −Copy data from the source computer to the removable storage device.Physically transport the removable device to the source computer.Copy data from the removable device to the destination computer.Some of the removable media that can use for transferring data between devices are −Magnetic tapesOptical discs like CDs, DVDs, and Blu-ray DiscsUSB flash drivesZip discs and floppy discsMemory cards and Memory sticksAdvantages ... Read More

Bandwidth The range of frequencies that are used for transmitting a signal without being substantially attenuated is called the bandwidth. It is calculated as the difference between the highest and the lowest frequencies. It is expressed in Hertz (Hz).For example, if the minimum frequency is 100 Hz and the maximum frequency is 1000 Hz, the bandwidth will be 900 Hz.The bandwidth of a transmission medium is the frequency width of the medium and is dependent upon its physical characteristics like thickness, material, length etc. For example, the bandwidth of a coaxial cable is 750 MHz ( MegaHertz).BasebandBaseband transmissions are those requiring ... Read More

Internet Standards refer to all the documented requirements both in technology as well as methodology pertaining to the Internet. The standardization process has three steps. The documentation laid down in a step is called the maturity level. There were previously three maturity levels but are merged to form only two maturity levels now which are:Proposed Standard: These are the standards that are ready for implementation. However, they can be revised according to circumstances of deployment. Draft Standard: When a Proposed Standard has been meticulously tested by at least two sites for at least 4 months, they are considered as Draft Standard. ... Read More

The service domains, legal status, and scopes of telecommunication companies worldwide are varied. In order to provide compatibility among different agencies, International Telecommunication Union (ITU) was formed. ITU is a specialized agency of the United Nations Organizations that standardizes information and communication technologies worldwide. ITU membership lays down the who’s who of the telecommunications world.Some of the main functions of the ITU areAllocates global use of radio spectrumAssigns satellite orbits through international cooperationDevelops standards for networking technologiesStrives to improve communications in developing and underdeveloped countries.Protects and supports communications and information exchange.ITU has three main sectorsITU-T: It is the Telecommunications Standardization ... Read More

Network StandardsNetworking standards define the rules for data communications that are needed for interoperability of networking technologies and processes. Standards help in creating and maintaining open markets and allow different vendors to compete on the basis of the quality of their products while being compatible with existing market products.During data communication, a number of standards may be used simultaneously at the different layers. The commonly used standards at each layer are −Application layer − HTTP, HTML, POP, H.323, IMAPTransport layer − TCP, SPXNetwork layer −IP, IPXData link layer − Ethernet IEEE 802.3, X.25, Frame RelayPhysical layer −RS-232C (cable), V.92 (modem)Types ... Read More

Ethernet is a set of technologies and protocols that are used primarily in LANs. However, Ethernet can also be used in MANs and even WANs. It was first standardized in the 1980s as IEEE 802.3 standard. Since then, it has gone through four generations, as shown in the following chartStandard Ethernet is also referred to as Basic Ethernet. It uses 10Base5 coaxial cables for communications. Ethernet provides service up to the data link layer. At the data link layer, Ethernet divides the data stream received from the upper layers and encapsulates it into frames, before passing them on to the ... Read More

X.25X.25 is a protocol suite defined by ITU-T for packet switched communications over WAN (Wide Area Network). It was originally designed for use in the 1970s and became very popular in 1980s. Presently, it is used for networks for ATMs and credit card verification. It allows multiple logical channels to use the same physical line. It also permits data exchange between terminals with different communication speeds.X.25 has three protocol layers Physical Layer: It lays out the physical, electrical and functional characteristics that interface between the computer terminal and the link to the packet switched node. X.21 physical implementer is commonly used ... Read More