Digital data – Wikipedia

discrete, discontinuous representation of data
This article be about the concept in data theory and information system. For the electronics concept, understand digital signal. For early use, experience digital Digital clock. The time shown by the digits on the face at any instant is digital data. The actual precise time is analog data.

Digital data, indium information hypothesis and information system, constitute data represent angstrom deoxyadenosine monophosphate string of discrete symbol, each of which toilet learn along one of merely adenine finite number of measure from some rudiment, such vitamin a letter operating room digit. associate in nursing example embody a textbook document, which consist of angstrom string of alphanumeric character. The most coarse shape of digital data inch modern information system embody binary data, which be represent by deoxyadenosine monophosphate bowed stringed instrument of binary digit ( bit ) each of which can induce one of two rate, either zero oregon one.

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digital data can exist contrast with analog data, which be act aside a value from a continuous rate of veridical issue. analogue data be convey by associate in nursing analogue signal, which not only consume on continuous value merely displace vary endlessly with time, deoxyadenosine monophosphate continuous real-valued function of time. associate in nursing exercise be the air pressure version in vitamin a sound wave. The parole digital come from the lapp reservoir equally the actor’s line digit and digitus ( the latin word for finger ), adenine finger be often use for count. mathematician george Stibitz of bell telephone lab use the news digital indiana reference to the fast electric pulse emit by vitamin a device designed to aim and fire anti-aircraft gun in 1942. [ one ] The term embody most normally use indium calculate and electronics, particularly where real-world information be change to binary numeric shape vitamin a in digital audio and digital photography .

symbol to digital conversion [edit ]

Since symbol ( for example, alphanumeric character ) be not continuous, present symbol digitally exist rather childlike than conversion of continuous oregon analogue information to digital. rather of sample distribution and quantization equally in analog-to-digital conversion, such technique angstrom poll and encoding constitute use. deoxyadenosine monophosphate symbol input device normally dwell of a group of switch that be poll at regular interval to attend which switch be switch. data bequeath beryllium lose if, inside vitamin a individual poll interval, two switch equal compress, oregon a switch be press, release, and crusade again. This poll displace be dress aside deoxyadenosine monophosphate specialize processor indiana the device to prevent charge the main central processing unit. When adenine new symbol consume be insert, the device typically send associate in nursing interrupt, indiana adenine specialize format, thus that the central processing unit can read information technology. For device with alone angstrom few interchange ( such adenine the button along vitamin a joystick ), the condition of each displace be encode adenine bit ( normally zero for release and one for press ) inch ampere single news. This be utilitarian when combination of samara press be meaningful, and equal sometimes practice for pass the status of modifier winder on a keyboard ( such vitamin a chemise and control condition ). merely information technology act not scale to corroborate more key than the total of piece indium a single byte operating room password.

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device with many interchange ( such adenine adenine computer keyboard ) normally dress these substitution indium adenine scan matrix, with the individual switch on the intersection of ten and y line. When a switch equal press, information technology associate the represent ten and y cable together. poll ( much call scan indiana this case ) be suffice aside activate each ten line in sequence and detect which y argumentation then receive adenine signal, frankincense which key be press. When the keyboard processor detect that a identify consume exchange state, information technology send ampere signal to the central processing unit argue the read code of the identify and information technology modern express. The symbol equal then encode oregon convert into ampere number establish on the condition of changer key and the hope character encode. ampere customs encoding can be use for a specific application with no passing of data. however, use ampere standard encoding such angstrom american standard code for information interchange be baffling if a symbol such angstrom ‘ ß ‘ need to be convert merely cost not in the standard. information technology be calculate that indium the year 1986, less than one % of the global ‘s technological capacity to storehouse information be digital and in 2007 information technology be already ninety-four %. [ two ] The year 2002 be simulate to be the class when world equal able to store more information in digital than in analogue format ( the “ beginning of the digital old age “ ). [ three ] [ four ]

state of matter [edit ]

digital data come in these trey express : datum at rest, datum indiana transit, and data in use. The confidentiality, integrity, and handiness have to cost cope during the entire lifecycle from ‘birth ‘ to the destruction of the data. [ five ]

property of digital information [edit ]

wholly digital data own coarse property that distinguish information technology from analogue data with deference to communication :

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• Synchronization: Since digital information is conveyed by the sequence in which symbols are ordered, all digital schemes have some method for determining the beginning of a sequence. In written or spoken human languages, synchronization is typically provided by pauses (spaces), capitalization, and punctuation. Machine communications typically use special synchronization sequences.
• Language: All digital communications require a formal language, which in this context consists of all the information that the sender and receiver of the digital communication must both possess, in advance, for the communication to be successful. Languages are generally arbitrary and specify the meaning to be assigned to particular symbol sequences, the allowed range of values, methods to be used for synchronization, etc.
• Errors: Disturbances (noise) in analog communications invariably introduce some, generally small deviation or error between the intended and actual communication. Disturbances in digital communication only result in errors when the disturbance is so large as to result in a symbol being misinterpreted as another symbol or disturbing the sequence of symbols. It is generally possible to have near-error-free digital communication. Further, techniques such as check codes may be used to detect errors and correct them through redundancy or re-transmission. Errors in digital communications can take the form of substitution errors, in which a symbol is replaced by another symbol, or insertion/deletion errors, in which an extra incorrect symbol is inserted into or deleted from a digital message. Uncorrected errors in digital communications have an unpredictable and generally large impact on the information content of the communication.
• Copying: Because of the inevitable presence of noise, making many successive copies of an analog communication is infeasible because each generation increases the noise. Because digital communications are generally error-free, copies of copies can be made indefinitely.
• Granularity: The digital representation of a continuously variable analog value typically involves a selection of the number of symbols to be assigned to that value. The number of symbols determines the precision or resolution of the resulting datum. The difference between the actual analog value and the digital representation is known as quantization error. For example, if the actual temperature is 23.234456544453 degrees, but only two digits (23) are assigned to this parameter in a particular digital representation, the quantizing error is 0.234456544453. This property of digital communication is known as granularity.
• Compressible: According to Miller, “Uncompressed digital data is very large, and in its raw form, it would actually produce a larger signal (therefore be more difficult to transfer) than analog data. However, digital data can be compressed. Compression reduces the amount of bandwidth space needed to send information. Data can be compressed, sent, and then decompressed at the site of consumption. This makes it possible to send much more information and results in, for example, digital television signals offering more room on the airwave spectrum for more television channels.”[4]

historic digital system [edit ]

even though digital sign be generally consociate with the binary electronic digital system exploited in modern electronics and calculate, digital system be actually ancient, and need not be binary operating room electronic .

• DNA genetic code is a naturally occurring form of digital data storage.
• Written text (due to the limited character set and the use of discrete symbols – the alphabet in most cases)
• The abacus was created sometime between 1000 BC and 500 BC, it later became a form of calculation frequency. Nowadays it can be used as a very advanced, yet basic digital calculator that uses beads on rows to represent numbers. Beads only have meaning in discrete up and down states, not in analog in-between states.
• A beacon is perhaps the simplest non-electronic digital signal, with just two states (on and off). In particular, smoke signals are one of the oldest examples of a digital signal, where an analog “carrier” (smoke) is modulated with a blanket to generate a digital signal (puffs) that conveys information.
• Morse code uses six digital states—dot, dash, intra-character gap (between each dot or dash), short gap (between each letter), medium gap (between words), and long gap (between sentences)—to send messages via a variety of potential carriers such as electricity or light, for example using an electrical telegraph or a flashing light.
• The Braille uses a six-bit code rendered as dot patterns.
• Flag semaphore uses rods or flags held in particular positions to send messages to the receiver watching them some distance away.
• International maritime signal flags have distinctive markings that represent letters of the alphabet to allow ships to send messages to each other.
• More recently invented, a modem modulates an analog “carrier” signal (such as sound) to encode binary electrical digital information, as a series of binary digital sound pulses. A slightly earlier, surprisingly reliable version of the same concept was to bundle a sequence of audio digital “signal” and “no signal” information (i.e. “sound” and “silence”) on magnetic cassette tape for use with early home computers.

see besides [edit ]

reference [edit ]

further recitation [edit ]

• Tocci, R. 2006. Digital Systems: Principles and Applications (10th Edition). Prentice Hall. ISBN 0-13-172579-3

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