A digital system uses discrete (that is, discontinuous) values to represent information for input, processing, transmission, storage, etc. By contrast, non-digital (or analog) systems use a continuous range of values to represent information. An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other In Mathematics, the word continuum has at least two distinct meanings outlined in the sections below Although digital representations are discrete, the information represented can be either discrete, such as numbers, letters or icons, or continuous, such as sounds, images, and other measurements of continuous systems. A number is an Abstract object, tokens of which are Symbols used in Counting and measuring. A letter is an element in an Alphabetic system of writing such as the Greek alphabet and its descendants An icon (from Greek εἰκών eikōn, "image" is a religious work of art most commonly a painting from Eastern Christianity.
The word digital comes from the same source as the word digit and digitus (the Latin word for finger), as fingers are used for discrete counting. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. A finger is a type of digit, an organ of manipulation and sensation found in the Hands of Humans and other Primates Normally humans have five digits
The word digital is most commonly used in computing and electronics, especially where real-world information is converted to binary numeric form as in digital audio and digital photography. Computing is usually defined like the activity of using and developing Computer technology Computer hardware and software. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical The binary numeral system, or base-2 number system, is a Numeral system that represents numeric values using two symbols usually 0 and 1. Digital audio uses Digital signals for Sound reproduction. This includes analog-to-digital conversion, digital-to-analog conversion, storage Digital photography is a form of Photography that utilizes Digital technology to make Digital images of subjects Such data-carrying signals carry electronic or optical pulses, the amplitude of each of which represents a logical 1 (pulse present and/or high) or a logical 0 (pulse absent and/or low).
When data are transmitted, or indeed handled at all, a certain amount of noise enters into the signal. is a one volume manga created by Tsutomu Nihei as a prequel to his ten-volume work Blame!. Noise can have several causes: data transmitted wirelessly, such as by radio, may be received inaccurately, suffer interference from other wireless sources, or pick up background noise from the rest of the universe. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. In physics interference is the addition ( superposition) of two or more Waves that result in a new wave pattern Microphones pick up both the intended signal as well as background noise without discriminating between signal and noise, so when audio is encoded digitally, it typically already includes noise. ELO.
Electric pulses transmitted via wires are typically attenuated by the resistance of the wire, and changed by its capacitance or inductance. Temperature variations can increase or reduce these effects. While digital transmissions are also degraded, slight variations do not matter since they are ignored when the signal is received. With an analog signal, variances cannot be distinguished from the signal and so provide a kind of distortion. In a digital signal, similar variances will not matter, as any signal close enough to a particular value will be interpreted as that value. Care must be taken to avoid noise and distortion when connecting digital and analog systems, but more when using analog systems.
Since symbols (e. g. , alphanumeric characters) are not continuous, converting symbols to digital form is rather simpler and less prone to data loss than analog to digital conversion. Alphanumeric is a is Portmanteau of Alphabetic and Numeric and is used to describe the collection of Latin letters and Arabic digits For other uses see Character. In Computer and machine-based Telecommunications terminology a character is a unit of Instead of sampling and quantization as in D/A (digital-to-analog) conversion, such techniques as polling and encoding are used. Polling, or polled operation in Computer science, refers to actively sampling the status of an external device by a client program as a synchronous activity A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page
A symbol input device usually consists of a number of switches that are polled at regular intervals to see which switches are pressed. 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 specialized processor in the device to prevent burdening the main CPU. When a new symbol has been entered, the device typically sends an interrupt to alert the CPU to read it. In Computing, an interrupt is an asynchronous signal from hardware indicating the need for attention or a synchronous event in software indicating the need for a change
For devices with only a few switches (such as the buttons on a joystick), the status of each can be encoded as bits (usually 0 for released and 1 for pressed) in a single word. A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling This is useful when combinations of key presses are meaningful, and is sometimes used for passing the status of modifier keys on a keyboard (such as shift and control). But it does not scale to support more keys than the number of bits in a single byte or word.
Devices with many switches (such as a computer keyboard) usually arrange these switches in a scan matrix, with the individual switches on the intersections of x and y lines. In Computing, a keyboard is an Input device partially modelled after the typewriter keyboard which uses an arrangement of buttons or keys 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 x line in sequence and detecting which y lines then have a signal, thus which keys are pressed. When the keyboard processor detects that a key has changed state, it sends a signal to the CPU indicating the scan code of the key and its new state. The symbol is then encoded, or converted into a number, based on the status of modifier keys and the desired character encoding. In Communications a code is a rule for converting a piece of Information (for example a letter, Word, Phrase, or A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page
A custom encoding can be used for a specific application with no loss of data. A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page However, using a standard encoding such as ASCII is problematic if a symbol such as 'ß' needs to be converted but is not in the standard. American Standard Code for Information Interchange ( ASCII)
Although digital signals are generally associated with the binary electronic digital systems used in modern electronics and computing, digital systems are actually ancient, and need not be binary nor electronic.