Editing Analog signal (section)

{{Short description|Continuous time-varying signal}}
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{{Use American English|date=July 2018}}

An '''analog signal''' ([[American English]]) or '''analogue signal''' ([[British English|British]] and [[Commonwealth English]]) is any [[continuous-time signal]] representing some other quantity, i.e., ''analogous'' to another quantity. For example, in an [[Analog recording|analog audio]] [[Audio signal|signal]], the instantaneous signal [[voltage]] varies continuously with the [[Sound pressure|pressure of the sound waves]].<ref>{{cite book |doi=10.1016/B978-1-876938-60-4.50013-6 |chapter=Communications and networking |title=Computers for Librarians |date=2003 |last1=Ferguson |first1=Stuart |last2=Hebels |first2=Rodney |pages=197–226 |isbn=978-1-876938-60-4 }}</ref>

In contrast, a [[digital signal]] represents the original time-varying quantity as a [[Sampling (signal processing)|sampled]] sequence of [[Quantization (signal processing)|quantized]] values. Digital sampling imposes some [[Nyquist frequency|bandwidth]] and [[dynamic range]] constraints on the representation and adds [[quantization noise]].

The term ''analog signal'' usually refers to [[electrical]] signals; however, [[Classical mechanics|mechanical]], [[pneumatic]], [[hydraulic]], and other systems may also convey or be considered analog signals.