Communication and Network

MODULATION

Modulation is the addition of information (or the signal) to an electronic or optical signal carrier. Modulation can be applied to direct current (mainly by turning it on and off), to alternating current, and to optical signals. In telecommunicatiuons, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted. Modulation of a sine waveform is used to transform a baseband message signal into a passband signal, for example low-frequency audio signal into a radio-frequency signal (RF signal).

DEMODULATION

Demodulation is the act of extracting the original information-bearing signal from a modulated carrier wave. A demodulator is an electric circuit (or computer program in a software defined radio) that is used to recover the information content from the modulated carrier wave. These terms are traditionally used in connection with radio receivers, but many other systems use many kinds of demodulators. Another common one is in a modem, which is a contraction of the terms modulator/demodulator.

BANDWIDTH

The amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second(bps) or bytes per second. For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).In computer networking, bandwidth in bit/s sometimes means the net bit rate (also known as peak bit rate, information rate or physical layer useful bit rate), channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system.

TCP/IP

Short for Transmission ControlProtocol/Internet Protocol, the suite of communications protocols used to connect hosts on the internet. TCP/IP uses several protocols, the two main ones being TCP and IP. Modern IP networking represents a synthesis of several developments that began to evolve in the 1960s and 1970s, namely the internet and local area networks, which emerged during the 1980s, together with the advent of the World Wide Web in the early 1990s.

NODE

In a network, a node is a connection point, either a redistribution point or an end point for data transmissions. In general, a node has programmed or engineered capability to recognize and process or forward transmissions to other nodes. The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of sending, receiving, or forwarding information over a communications channel.

CLIENT

The client part of a client-server architecture. Typically, a client is an application that runs on a personal computer or workstation and relies on a server to perform some operations. The client-server model is still used today. Client and server can run on the same machine and connect via Unix domain sockets. Using Internet sockets a user may connect to a service operating on a possibly remote system through the Internet protocol suite. Servers set up listening sockets, and clients initiate connections that a server may accept. Web browsers are clients that connect to web servers and retrieve web pages for display.

SERVER

In computer networking, a server is a program that operates as a socket listener. The term server is also often generalized to describe a host that is deployed to execute one or more such programs. A server computer is a computer, or series of computers, that link other computers or electronic devices together. They often provide essential services across a network, either to private users inside a large organization or to public users via the internet.

NETWORK OPERATING SYSTEM

Abbreviated as NOS, an operating system that includes special functions for connecting computer and devices into a local area network (LAN). Some operating systems, such as UNIX and the Mac OS, have networking functions built in. The Network Operating System can also do the following: Centrally manage network resources, such as programs, data and devices. Moreover, secure access to a network and to allow remote users to connect to a network. Next is to, allow users to connect to other networks like the internet. Back up data is made sure it's always available.

NETWORK ADMINISTRATOR

A network administrator is a person responsible for the maintenance of computer hardware and software that comprises a computer network. Under general direction designs, supports, maintains, and evaluates computer networking and telecommunication systems; installs, configures, and maintains both physical and virtual computer servers; maintains employee e-mail, dial-up user accounts and card key access accounts; performs other related duties as assigned.

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Secondary Storage

DISK CACHING

A portion of RAM used to speed access to data on a disk. The RAM can be part of the disk drive itself (sometimes called a hard disk cache or buffer) or it can be general-purpose RAM in the computer that is reserved for use by the disk drive (sometimes called a soft disk cache). Hard disk caches are more effective, but they are also much more expensive, and therefore smaller. Nearly all modern disk drives include a small amount of internal cache.

FILE COMPRESSION

File compression is commonly used when sending a file from one computer to another over a connection that has limited bandwidth. The compression basically makes the file smaller and, therefore, the sending of the file is faster. The design of data compression schemes therefore involves trade-offs among various factors, including the degree of compression, the amount of distortion introduced (if using a lossy compression scheme), and the computational resources required to compress and decompress the data

FILE DECOMPRESSION

Data compression is the process of making computer files, folders or information smaller than they originally intended to be. Certain types of data compression can be read or used in the compressed form, for example with compressed music formats such as mp3, while other files require decompression for the user to be able to use them. Decompression requires processing power. Decompression of file archives can be achieved on all computers, but live decompression of video requires much more powerful hardware.

INTERNET HARD DRIVE

Internet hard drives have served to offering a creative new solution to the issue of data storage.The sole purpose of an Internet hard drive is to offer a means of accessing your computer files (pictures, documents, music, videos, etc.) from any computer, as long as that computer has access to the Internet. By uploading regular backups of your files, you can remain immune from the dangers of file loss due to viruses or your hard drive crashing; your local computer can be completely destroyed and yet the files which were stored online would remain safe and unharmed.

OPTICAL DISK DRIVE

In computing, an optical disc drive (ODD) is a disk drive that uses laser light or electromagnetic waves near the light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from discs, but recent drives are commonly both readers and recorders. Recorders are sometimes called burners or writers.Compact discs, DVDs, and Blu ray discs are common types of optical media which can be read and recorded by such drives.

SOLID-STATE STORAGE

Solid-state storage is a nonvolatile, removable storage medium that employs integrated circuits (ICs) rather than magnetic or optical media. It is the equivalent of large-capacity,nonvolatile memory. Examples include flash memory Universal Serial Bus (USB) devices and various proprietary removable packages intended to replace external hard drives.The main advantage of solid-state storage is the fact that it contains no mechanical parts.

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Input and Output

ERGONOMIC KEYBOARD

An ergonomic keyboard is a computer keyboard designed with ergonomic considerations to minimize muscle strain and a host of related problems. Typically such keyboards are constructed in a V shape, to allow right and left hands to type at a slight angle more natural to the human form.

INKJET PRINTER

A type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct the ink onto the paper in the desired shapes. Ink-jet printers are capable of producing high quality print approaching that produced by laser printers. A typical ink-jet printer provides a resolution of 300 dots per inch, although some newer models offer higher resolutions.

LASER PRINTER

A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and multifunction printers (MFPs), laser printers employ a xerographic printing process, but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor.

MAGNETIC-INK CHARACTER RECOGNITION

Magnetic Ink Character Recognition, or MICR, is a character recognition technology used primarily by the banking industry to facilitate the processing of cheques. The technology allows computers to read information (such as account numbers) off printed documents. Unlike barcodes or similar technologies, however, MICR codes can be easily read by humans.The use of magnetic printing allows the characters to be read reliably even if they have been overprinted or obscured by other marks, such as cancellation stamps and signature

OPTICAL-CHARACTER RECOGNITION

Optical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of scanned images of handwritten, typewritten or printed text into machine-encoded text. It is widely used to convert books and documents into electronic files, to computerize a record-keeping system in an office, or to publish the text on a website. All OCR systems include an optical scanner for reading text, and sophisticated software for analyzing images.

OPTICAL-MARK RECOGNITION

Short for optical mark recognition, the technology of electronically extracting intended data from marked fields, such as checkboxes and fill-infields, on printed forms. OMR technology scans a printed form and reads predefined positions and records where marks are made on the form. A common OMR application is the use of "bubble sheets" for multiple-choice tests used by schools.

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