Talk:Crest factor

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[edit] Table

The table of the article is wrong.

The mean values of sine, triangle and square wave signals are all 0.

The values given are for (perfectly) rectified signals.

KjellElec

Yes. Also, the meaning of waveform factor is not explained. Omegatron 04:33, 21 October 2006 (UTC)
It appears to be the RMS divided by the mean, though I don't know how it is used. — Omegatron 07:52, 9 March 2007 (UTC)

[edit] Reformat

Please break up the table into individual images and editable math formulas in an HTML table. I'll do it if no one else does, but I don't have time right now. — Omegatron 19:38, 20 October 2006 (UTC)

The table should also be expanded to include Gaussian white noise, pink noise, compressed mastered CD audio, raw audio from a microphone, etc. etc. — Omegatron 19:59, 20 October 2006 (UTC)

Starting:

Wave type Waveform Mean value (rectified) Waveform factor RMS value Crest factor
Sine wave {2 \over \pi} \approx 0.637 {\pi \over 2 \sqrt{2}} \approx 1.11 {1 \over \sqrt{2}} \approx 0.707 \sqrt{2} \approx 1.414
Half-wave rectified sine {1 \over \pi} \approx 0.318 {\pi \over 2} \approx 1.571 {1 \over 2} = 0.5 2
Full-wave rectified sine {2 \over \pi} \approx 0.637 {\pi \over 2 \sqrt{2}} \approx 1.11 {1 \over \sqrt{2}} \approx 0.707 \sqrt{2} \approx 1.414
Triangle wave {1 \over 2} = 0.5 {2 \over \sqrt{3}} \approx 1.155 {1 \over \sqrt{3}} \approx 0.577 \sqrt{3} \approx 1.732
Sawtooth wave {1 \over 2} = 0.5 ? ? ?
Square wave 1 1 1 1

Obviously we should create dedicated images. These are just placeholders. Omegatron 04:12, 21 October 2006 (UTC)

I created better images and they are now in the article and here. — Omegatron 05:05, 9 March 2007 (UTC)

http://www.dliengineering.com/downloads/crest%20factor.pdf

I think we should more clearly discuss the mean values are obtained by rectification. At a quick-glance, these values seem incorrect, though they are just rectified.

What do you mean? — Omegatron 05:05, 9 March 2007 (UTC)

[edit] Peak Value?

Suppose we have a waveform whose peak values are asymmetric. That is, the magnitude of the negative peak is different from the magnitude of the positive peak. Which peak is used when calculating crest factor: the higher or lower magnitude? Or should the average of the peak magnitudes be used?

65.161.52.184 21:22, 18 December 2006 (UTC) Scott L.

The higher value would be used. — Omegatron 05:05, 9 March 2007 (UTC)
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