Editing Crest factor (section)

{{Short description|Peak divided by the Root mean square (RMS) of the waveform}}
'''Crest factor''' is a parameter of a [[waveform]], such as [[alternating current]] or sound, showing the ratio of peak values to the effective value. In other words, crest factor indicates how extreme the peaks are in a waveform. Crest factor 1 indicates no peaks, such as [[direct current]] or a [[Square wave (waveform)|square wave]]. Higher crest factors indicate peaks, for example sound waves tend to have high crest factors.

Crest factor is the [[peak amplitude]] of the waveform divided by the [[root mean square|RMS]] value of the waveform.

The '''peak-to-average power ratio''' ('''PAPR''') is the peak amplitude squared (giving the peak ''power'') divided by the [[root mean square|RMS]] value squared (giving the average ''power'').<ref>{{cite web |title=Wireless 101: Peak to average power ratio (PAPR) |url=http://www.eetimes.com/design/microwave-rf-design/4017754/Wireless-101-Peak-to-average-power-ratio-PAPR-}}</ref> It is the square of the crest factor.

When expressed in [[decibel]]s, crest factor and PAPR are equivalent, due to the way decibels are [[Decibel#Definition|calculated for power ratios vs amplitude ratios]].

Crest factor and PAPR are therefore [[dimensionless quantities]].  While the crest factor is defined as a positive [[real number]], in commercial products it is also commonly stated as the ratio of two whole numbers, e.g., 2:1. The PAPR is most used in signal processing applications. As it is a power ratio, it is normally expressed in [[Decibel|decibels (dB)]].<!-- the next ref applies only to speakers--> The crest factor of the test signal is a fairly important issue in [[loudspeaker]] testing standards; in this context it is usually expressed in dB.<ref>[https://jblpro.com/en/site_elements/speaker-power-requirements-faq   JBL Speaker Power Requirements], which is applying the [[International Electrotechnical Commission|IEC]] standard 268-5, itself more recently renamed to 60268-5</ref><ref>[[Audio Engineering Society|AES]]2-2012 standard, Annex B (Informative) Crest Factor, pp. 17-20 in the 2013-02-11 printing</ref><ref>"Dr. Pro-Audio", [http://www.doctorproaudio.com/doctor/temas/powerhandling.htm Power handling], summarizes the various speaker standards</ref>

The minimum possible crest factor is 1, 1:1 or 0&nbsp;dB.