Digital data

Digital data , in information theory and information systems , are discrete, discontinuous representations of information or works, as contrasted with continuous, or analog signals qui behave in a Continuous Manner, gold Represent information using a continuous function .

Although digital representations are the subject matter of discrete mathematics , the information represented can be either discrete, such as numbers and letters , or it may be continuous, such as sounds, images, and other measurements.

The word digital comes from the same source as the words digit and digitus (the Latin word for finger ), as fingers are often used for discrete counting. Mathematician George Stibitz of Bell Telephone Laboratories used the word digital in reference to the fast electric pulse Emitted by a device designed to aim and fire anti-aircraft guns in 1942. [1] The term is MOST Commonly used in computing and electronics ,

Symbol to digital conversion

Since symbols (for example, alphanumeric characters ) are not continuous, representing symbols. Instead of sampling and quantization in analog-to-digital conversion , such techniques as polling and encoding are used.

A symbol input device, which consists of a group of switches that are polled at regular intervals to see which switches are switched. Data will be lost if, within a single polling interval, two switches are pressed, or a switch is pressed, released, and pressed again. This polling can be done by a special processor in the CPU . When a new symbol has been entered, the device typically sends an interrupt , in a specialized format, so that the CPU can read it.

For devices with only A Few switches (Such As the buttons we joystick ), the status of Each can be encoded as bits (usually 0 for released and 1 for pressed) in a single word. This is useful when combining key presses, meaning “shift and control”. But it does not matter whether it is a single byte or word.

Devices with many switches (such as a computer keyboard ). When a switch is pressed, it connects the corresponding x and y lines together. Polling (often called scanning in this case) is done by activating each line in sequence and detecting which lines then have a signal, thus which keys are pressed. When the keyboard processor detects a key, it sends a signal to the CPU indicating the scanning of the key and its new state. The symbol is then encoded , or converted into a number, based on the status of the keys and the desired character encoding .

A custom encoding can be used for a specific application with no loss of data. However, as a standard encoding such as ASCII is a problem.

It is estimated that in the year 1986 it was already 94%. [2] The year 2002 is assumed to be the Year When human kind Was ble to store more information in digital than in analog formats (the “beginning of the digital age “). [3] [4]

Properties of digital information

All digital information possesses common properties that distinguish it from analog data with respect to communications:

  • 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 , qui in this context Consists of all the information sender and receiver que le of the digital communication must Possess Both, in advance, in order for the communication to be successful. The syntax of the syntax is that the syntax of the syntax is the same.
  • Errors: Disturbances ( noise ) in analog communications invariably Introduce Some, Generally small deviation or error entre The Intended and actual communication. Disturbances in a digital communication not disturbed by the disturbance of the disturbance. It is possible to have an error-free digital communication. Further, techniques such as check codes may be used to detect errors and guarantee error-free communications through redundancy or retransmission. 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 unpredictable and broad 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. Since 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), 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. Bandwidth space to send information, data and beat compressed, sent and then decompressed to the site of consumption. Television channels. ” [4]

Historical digital systems

Even though digital signals are associated with the binary electronic digital systems used in modern electronics and computing, digital systems are actually ancient, and need not be electronic. Citation needed ]

  • 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 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.
  • beacon is 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, medium 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 system was the first binary format for character encoding, using a six-bit code rendered as dot patterns.
  • Flag semaphore uses rods or flags 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, 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 bit earlier, surprisingly reliable version of the same concept was to bundle a sequence of audio digital “signal” and “no signal” information (ie “sound” and “silence”) on magnetic tape tape for use with early home computers .

See also

  • Analog-to-digital converter
  • Binary number
  • Comparison of analog and digital recording
  • Data (computing)
  • Digital architecture
  • Digital art
  • Digital control
  • Digital divide
  • Digital electronics
  • Digital Infinity
  • Digital native
  • Digital Physics
  • Digital recording
  • Digital Revolution
  • Digital video
  • Digital-to-analog converter

References

  1. Jump up^ Ceruzzi, Paul E (June 29, 2012). Computing – A Concise History . MIT Press . ISBN 978-0-262-51767-6 .
  2. Jump up^ “The World’s Technological Capacity to Store, Communicate, and Compute Information,”especiallySupporting online material, Martin Hilbert and Priscila López (2011),Science (journal), 332 (6025), 60-65; Free access to the article via here: martinhilbert.net/WorldInfoCapacity.html
  3. Jump up^ “video animation on The World’s Technological Capacity to Store, Communicate, and Compute Information from 1986 to 2010
  4. ^ Jump up to:a b Miller, Vincent (2011). Understanding digital culture . London: Sage Publications. dry. “Convergence and the contemporary media experience”. ISBN 978-1-84787-497-9 .

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