Lesson plan
Crest factor
Crest factor is a parameter of a waveform, such as alternating current or sound, showing the ratio of largest value to the more typical value. More specifically, crest factor is the peak amplitude of the waveform divided by the root mean square (RMS) value of the waveform. The minimum possible crest factor is 1 or 1:1. 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. Higher crest factors indicate more pronounced peaks, for example sound waves tend to have high crest factors. The peak-to-average power ratio (PAPR) is the peak power (peak amplitude squared) divided by the average power (mean square or squared RMS). PAPR is the square of the crest factor. Crest factor and PAPR are both 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 decibels (dB). When expressed in decibels, crest factor and PAPR are numerically equal, due to the way decibels are calculated for power ratios vs amplitude ratios. 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.
Article summary
Crest factor is a parameter of a waveform, such as alternating current or sound, showing the ratio of largest value to the more typical value. More specifically, crest factor is the peak amplitude of the waveform divided by the root mean square (RMS) value of the waveform. The minimum possible crest factor is 1 or 1:1. 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. Higher crest factors indicate more pronounced peaks, for example sound waves tend to have high crest factors. The peak-to-average power ratio (PAPR) is the peak power (peak amplitude squared) divided by the average power (mean square or squared RMS). PAPR is the square of the crest factor. Crest factor and PAPR are both 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 decibels (dB). When expressed in decibels, crest factor and PAPR are numerically equal, due to the way decibels are calculated for power ratios vs amplitude ratios. 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.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.