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Digital Signal ○꠹｜Definition｜1st｜20251119205401-00-⌔
Digital signal
A digital signal is a signal that represents data as a sequence of discrete values; at any given time it can only take on, at most, one of a finite number of values.123 This contrasts with an analog signal, which represents continuous values; at any given time it represents a real number within an infinite set of values.
Simple digital signals represent information in discrete bands of levels. All levels within a band of values represent the same information state.1 In most digital circuits, the signal can have two possible valid values; this is called a binary signal or logic signal.4 They are represented by two voltage bands: one near a reference value (typically termed as ground or zero volts), and the other a value near the supply voltage. These correspond to the two values zero and one (or false and true) of the Boolean domain, so at any given time a binary signal represents one binary digit (bit). Because of this discretization, relatively small changes to the signal levels do not leave the discrete envelope, and as a result are ignored by signal state sensing circuitry. As a result, digital signals have noise immunity; electronic noise, provided it is not too great, will not affect digital circuits, whereas noise always degrades the operation of analog signals to some degree.5
Digital signals having more than two states are occasionally used; circuitry using such signals is called multivalued logic. For example, signals that can assume three possible states are called three-valued logic.
In a digital signal, the physical quantity representing the information may be a variable electric current or voltage, the intensity, phase or polarization of an optical or other electromagnetic field, acoustic pressure, the magnetization of a magnetic storage media, etcetera. Digital signals are used in all digital electronics, notably computing equipment and data transmission.
Printed 2026-06-28.
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Link to original Footnotes
Robert K. Dueck (2005). Digital Design with CPLD Applications and VHDL. Thomson/Delmar Learning. ISBN 1401840302. Archived from the original on 2017-12-17. Retrieved 2017-08-30. A digital representation can have only specific discrete values ↩ ↩2
Proakis, John G.; Manolakis, Dimitris G. (2007-01-01). Digital Signal Processing. Pearson Prentice Hall. ISBN 9780131873742. Archived from the original on 2016-05-20. Retrieved 2015-09-22. ↩
Analogue and Digital Communication Techniques Archived 2017-12-17 at the Wayback Machine: “A digital signal is a complex waveform and can be defined as a discrete waveform having a finite set of levels” ↩
“Digital Signal”. Archived from the original on 2016-03-04. Retrieved 2016-08-13. ↩
Horowitz, Paul; Hill, Winfield (1989). The Art Of Electronics, 2nd Ed. Cambridge University Press. pp. 471–473. ISBN 0521370957. ↩
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