# Talk:Decibel

Page contents not supported in other languages.

## A Commons file used on this page or its Wikidata item has been nominated for deletion

The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion:

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 22:39, 7 January 2022 (UTC)

## Fourier transform or Fourier trnasform, and logarithms

There is a complication with Fourier transform that it works in linear space, but sometimes people want a spectrum in logarithmic space. As well as I know it, there is no easy trick to doing it, like there is with FFT. That is, no fast logarithmic transform. I don't know what means anything should go here, though, but it might be interesting to mention spectra with a logarithmic frequency axis. Gah4 (talk) 01:03, 10 February 2022 (UTC)

That's probably not really relevant for the decibel article, but you may want to check out the constant-Q transform, which sounds close to what you're talking about. Hqb (talk) 07:15, 10 February 2022 (UTC)
I think you are right, but I wanted it to get discussed to be sure. Gah4 (talk) 07:49, 10 February 2022 (UTC)

## dBd vs dBi for antennas

In the page it is stated that 1 dBd equals 2.15 dBi. Unfortunately, this is only true in free space. At ground levels, depending on the antenna height, this can be 6-7 dBi. 5.168.129.245 (talk) 16:49, 25 March 2022 (UTC)

## Clarify in lede how decibel is strictly a relative value but may in practice may be used in context of fixed reference

Frustrating thing with decibel is how it strictly represents a relative value but in common usage or in specific practices is simultaneously used to represent an "absolute" value relative to a reference that may or may not be explicitly stated. I'm sorry I got carried away with making edits that got reverted. I'll just put my attempt here in talk...hopefully someone can figure out something better than the self-contradictory way it is written there currently:

"The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B) that expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. In practice, the decibel may be expressed in the context of a fixed reference value, in which case its symbol should be suffixed with letter codes to indicate the reference value (for examples see § Suffixes and reference values)." Em3rgent0rdr (talk) 15:55, 27 July 2022 (UTC)

No need to apologise. Your edits were perfectly legitimate, and in the spirit of BRD. My concern about your text proposal is the use of the word "should", when (IMO) "should not" is more appropriate. How about this
"The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B) that is used to express the ratio of two values of a power or root-power quantity on a logarithmic scale. In practice, the decibel may be expressed in the context of a fixed reference value, in which case its symbol is sometimes suffixed with letter codes to indicate the reference value (for examples see § Suffixes and reference values), though the practice of using such a suffix is deprecated by standards bodies."
Dondervogel 2 (talk) 20:53, 27 July 2022 (UTC)
ah yes good point that I should not use "should" when talking about something deprecated by standards bodies. Yes that variant looks good. Em3rgent0rdr (talk) 21:06, 27 July 2022 (UTC)
Great! Thank you for listening. Dondervogel 2 (talk) 21:47, 27 July 2022 (UTC)

## Article issues and classification

The article has not qualified for B-class since tagged "citation needed" in 2008 (also February 2021). There is also a "clarification needed" tag dated March 2018. This is a technical article with a lot of formulas that need sourcing. Reassess to C-class. -- Otr500 (talk) 00:53, 1 March 2023 (UTC)