Wikipedia:Articles for deletion/Discrete frequency

The following discussion is an archived debate of the proposed deletion of the article below. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in a deletion review). No further edits should be made to this page.

The result was no consensus. Stifle (talk) 16:17, 18 February 2011 (UTC)[reply]

Discrete frequency

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Nothing in this article is correct. The definition of the topic is nonsense, probably just misparsed from the sentence "Since the DFT provides a discrete frequency representation of a finite-duration sequence" which is the only mention of this word pair in the only cited source. All the content is represented correctly already in other articles. Dicklyon (talk) 22:28, 10 February 2011 (UTC)[reply]

Delete per nom. There is no concept known as "discrete frequency". --Lambiam 00:58, 11 February 2011 (UTC)[reply]

But there is, the term is used to distinguish between a single frequency and a number of frequencies. For exampe an oscilloscope can be used at a discrete frequency or swept through them. I'm not going to pretend this link is easy to read, it is just the first I came across. [1] Szzuk (talk) 19:18, 17 February 2011 (UTC)[reply]

You will have to be more specific when you say "definitions and factoids in this article are just wrong, apparently just made up" or call it "nonsense". I am the original author of the article, so it might sound like I'm challenging you. But I'm genuinely intrigued as to how you find nothing of interest here, whatsoever. Given that you are an engineer in the Valley (I saw that on your page), the article might be really elementary to you. But that's what its point was, when I created it. The title is a little dubious though, I'll agree. --Tt801 (talk) 03:48, 11 February 2011 (UTC)[reply]

Well it's hard to make a right article when the title doesn't mean anything, or doesn't mean what you think it is that you're writing about. It's not elementary, because it doesn't say much that's true. I attached "dubious" tags to the most obviously wrong bits. Read sampling rate and discrete-time signal and sampling theorem and such, and tell us what you meant to write about that's not already covered in one of those. And note that the sampling theorem does not have a converse to tell you what sampling rate is required (it is not true that "the sampling frequency has to be at the least double of the highest frequency of the input signal"; read what it does say, realize that it doesn't have a converse, and maybe you'll learn something insightful). Dicklyon (talk) 04:19, 11 February 2011 (UTC)[reply]

Sampling theorem does say that you require at least double the highest frequency to represent it completely, I don't know how else to put forth this simple fact to you. What I wrote was not a converse of the theorem, it IS the theorem. Let us take one of the "dubious" points: how is the fact that

-\pi \leq \omega \leq \pi

contains all discrete frequencies, dubious? I'd like to direct your attention to frequency warping that occurs via BLT, e.g. or the aliasing that occurs due to impulse invariance transformation. This interval contains all frequencies in the sense, that once multiplied with the sampling frequency, it yields the "original analog" frequency axis back, without loss of information (provided of course you had initially satisfied Nyquist's criterion).--Tt801 (talk) 13:20, 11 February 2011 (UTC)[reply]

Sounds like you didn't read the article. The sampling theorem provides only a sufficient condition for perfect reconstruction, not a necessary condition. It doesn't say you can't sample a signal with a sampling rate that's less than twice the highest frequency present; it doesn't even tell you, or imply, that you'll have aliasing problems if you do. This is discussed in the article, including fields that use counterexamples to such converses. Dicklyon (talk) 16:49, 11 February 2011 (UTC)[reply]

Note: This debate has been included in the list of Technology-related deletion discussions. -- • Gene93k (talk) 14:46, 11 February 2011 (UTC)[reply]

Redirect to Discrete signal. Nothing worth merging, but possible search term. -Atmoz (talk) 21:57, 11 February 2011 (UTC)[reply]
Users searching with this term are more likely searching for "discrete frequency noise" (DFN), noise that manifests as a combination of whistle tones, or for "discrete-frequency Wigner distribution", a variant of the Wigner quasi-probability distribution in which the frequency domain is discretized. It is not clear to me that their interests are best served by the recommended redirect. --Lambiam 22:53, 13 February 2011 (UTC)[reply]
Good point. I suppose it could be turned into a disambiguation page. Or a redirect to Wigner quasi-probability distribution is good too. The bulk of my comment stands though; there isn't really anything in this article that could be usefully merged anywhere, but it is a possible search term. Therefore, we should have something here instead of simply deleting the article. -Atmoz (talk) 16:33, 14 February 2011 (UTC)[reply]
A redirect to Wigner quasi-probability distribution (or linking to there from a disambiguation page) is totally unhelpful if the target page does not even use the word "discrete" – which it doesn't and is not likely to do anytime soon, as this is a quite arcane corner of a rather specialized topic. --Lambiam 20:16, 14 February 2011 (UTC)[reply]

I don't understand by what logic you conclude it's a "possible search term" any more than any other random bigram would be. Is it a "useful" search term? Seems unlikely to me. Dicklyon (talk) 16:41, 14 February 2011 (UTC)[reply]
Whether it's useful is dependent upon each specific user. In January, the page has ~1400 page views. There are limited internal links to this article, so it seems likely that at least some are searching for it (either internally or through Google). Redirect are cheap. Disamb pages are cheap. If a user naively searches for "discrete frequency", I think it's in our best interest as a reference source to usher them to information that may be related to what they are searching for. By deleting the page and leaving nothing behind to help them, we're basically saying they are too stupid to be trying to use Wikipedia. And that's not acceptable to me. -Atmoz (talk) 16:55, 14 February 2011 (UTC)[reply]
There are so many possible search terms that have no page: Flexible rotor, Repeated substring, Burnt red bean, Centralized decision, and so on ad infinitum. If this is really unacceptable to you, you have a lot of work ahead. While redirects and disambiguations pages are cheap, they need a plausible target to refer the reader to, something that is missing in this case. --Lambiam 20:16, 14 February 2011 (UTC)[reply]

Delete The content is seriously confused and I can see no way to salvage it. At the very least it should be pointed out that discrete frequencies arise from a signal which repeats in time not from a discretely time-sampled signal. I don't know of a page which makes this clear, so I do not think that a redirect would help. The search engine is at least as likely to point a user to a useful page as is a redirect. Dingo1729 (talk) 18:02, 17 February 2011 (UTC)[reply]

Keep. Being a physicist I'm confident it is a notable topic. However this article is awful, it should be left and tagged to await an expert or returned to a stub while someone who knows what they are talking about comes along to rewrite it. Szzuk (talk) 18:29, 17 February 2011 (UTC)[reply]

Comment. Have simplified lead section and added a real world reference for their use in oscilloscopes. Also added expert tag. Szzuk (talk) 19:48, 17 February 2011 (UTC)[reply]

The experts have weighted in already, and "a discrete frequency domain spectrum" is not evidence that the bigram "discrete frequency" means anything. This is just "discrete" modifying "frequency-domain spectrum", with the hyphen missing. Dicklyon (talk) 20:23, 17 February 2011 (UTC)[reply]

Who are the experts? You? I'd say your opinion was the problem. Perhaps you should write wp all by yourself. Szzuk (talk) 20:38, 17 February 2011 (UTC)[reply]

Please, no personal attacks. An article on discrete frequencies doesn't make sense. It is impossible to fill in the dots in a sentence of the form "In digital signal processing, a discrete frequency is defined as ..." while at the same time making this statement verifiable by citing reliable sources. It is not a coincidence that none of the sources you give contains anything remotely resembling the nonsensical definition in the article. It is meaningless to say: "this frequency is discrete, but this one isn't". In the phrase "discrete frequency domain", that which is discrete is the frequency domain, and not the frequencies constituing the domain. What we have here is like an article on "Homemade chicken" as being an ingredient of homemade chicken soup. --Lambiam 23:58, 17 February 2011 (UTC)[reply]

Well, I am indeed one of several with DSP expertise who have said that there's no topic here, just an extracted word pair. My point is simply that calling for experts is going to get me or someone like me to say that again. It is not my point to try to rely on credentials in my arguments, as I believe credentials are irrelevant on wikipedia, but when you call for an expert, you get what you get. I'd be happy to hear from others. Dicklyon (talk) 00:18, 18 February 2011 (UTC)[reply]

Pulling books from my bookcase, none of the following have an entry for "discrete frequency" in the index:

"Digital Signal Processing" Oppenheim and Schafer

"Time Series" Norbert Weiner

"Digital Signal Processing" Rabiner and Gold

"Reference Data for Radio Engineers"

"Time Series Analysis" Box and Jenkins

"Measurement of Power Spectra" Blackman

"Acoustical Measurements" Beranek

"Theory of Hearing" Wever

"Digital and Kalman Filtering" Bozic

"Acoustics" Beranek

and a few others.

If this phrase were notable it would be at least be mentioned in an index in one of these books. The phrase is very clearly not notable. Dingo1729 (talk) 00:37, 18 February 2011 (UTC)[reply]

The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in a deletion review). No further edits should be made to this page.