Talk:Nyquist frequency

message: In the nyquist article it's mentioned that the transition band for the antialius filter is 2000hz.  This should not be stated without first defining the order (more specificaly the poles and zero) of the filter since the fiter characteristics define the transition band.  It's very confusing without this information, at first glance I thought the band pass was 2000hz.  --03:01, 9 October 2012 (UTC)
replies: text: I took that malformed tag out, since it was a redlink.  And I didn't see a corresponding proposal at Nyquist rate.  Maybe your caps key is broken. Dicklyon (talk) 23:03, 10 June 2008 (UTC)
replies: text: Given that you have not responded to the underlying comment; specifically that the folding frequency and the Nyquist rate are the same fundamental object; would you care to comment on the underlying proposal? HatlessAtless (talk) 13:18, 11 June 2008 (UTC)
replies: text: They are not.  See also my response to your remarks on my talk page. Dicklyon (talk) 14:50, 11 June 2008 (UTC)
replies: text: They are definitely not. I remove the template. Mange01 (talk) 10:00, 29 August 2008 (UTC)
thread_title:  Merge with nyquist Rate? 

message: I was about to revert this edit but spent so long thinking about it that someone else beat me to it by the time I got round to pressing the button.  So even though I didn't revert it (honest guv) here are my reasons for doing so.  Firstly the edit is introducing a subtle discussion into the lede concerning Nyquist rate, but this article is about Nyquist frequency, it should not be in the lede, possibly it should not be in this article.  It also introduced a parameter, epsilon, that is not defined.  One cannot say that the Nyquist rate is defined as twice the max frequency and then go on to say it is something different.  Possibly the system will not work at exactly the Nyquist rate (for reasons of imperfect low-pass filters? which is discussed in the body of the article) but that is a different matter.  I was also unhappy that the quoted reference (presumably this book) does not get any hits for "Nyquist" according to a google search. SpinningSpark 00:13, 17 October 2009 (UTC)
replies: text: I reverted it; I think he doesn't understand the idea of a bound; I hadn't even noticed that the topic of the change wasn't the topic of this article. Dicklyon (talk) 02:02, 17 October 2009 (UTC)
thread_title:  Nyquist rate and epsilon 

message: This page seems to be very centred around those with an engineering background - there is a plethora of undefined terms such as 'foldback' or 'bandwidth'.  Since I came to this page to hear some form of discussion of the optimal sampling rate for a DFT, this wasn't a great experience.  Is there really no stronger bound on the sampling rate than 'at least twice the frequency of the signal'?  What if I don't know the signal frequency a priori? 131.111.17.143 (talk) 15:44, 3 November 2009 (UTC)
replies: text: The guideline "at least twice the frequency of the signal" seems to be already plenty of guidance for you; if you don't even know the frequencies in your signals, this tells you that you need to find out.  The article is unavoidably technical, as it's a technical topic.  If the terms like bandwidth are not linked to appropriate articles for more info, that can be fixed.  I added a small explanation of folding.  Dicklyon (talk) 18:09, 5 November 2009 (UTC)
replies: text: I disagree that 'technical topics' are necessarily unclear to the layperson; a good writing style should make the broad structure of the meaning clear - and since my problem is that I'm exploring the state-space of an unstable  linear magnetohydrodynamic problem; if I can /find/ the (complex) frequencies I've finished my task.  Thanks for the added info. 131.111.17.143 (talk) 11:21, 9 November 2009 (UTC)
replies: text: I agree totally that the writing should be clear. Dicklyon (talk) 16:49, 9 November 2009 (UTC)
replies: text: Looking back over my first response, I hope I didn't seem rude - it wasn't intended. 131.111.17.143 (talk) 17:27, 10 November 2009 (UTC)
thread_title: Placeholder heading

message: While the Nyquist frequency is generally the cut-off frequency in designs due to its importance, "cut-off frequency" is certainly not a synonym of Nyquist frequency. If nobody has an issue with this I will remove it. Oldmaneinstein (talk) 21:50, 16 April 2010 (UTC)
replies: text: Completely agree, that is either a misunderstanding or taken from an eccentric source. SpinningSpark 23:13, 16 April 2010 (UTC)
thread_title: Nyquist frequency as cut-off frequency?

message: The recently added proof of the DFT's periodicity won't help the typical person who comes here to learn what Nyquist frequency means.  He might not even know what a Fourier transform is.  Notice that the figure depicting aliases and folding is not even a spectrum of frequencies.  It shows just one sinusoid at 0.6 fs and three other frequencies that would produce the same samples.  Then it shows (by the red lines) an example of what would happen if that sinusoid was altered in frequency and amplitude between 0.5 fs and 1.0 fs.
Also, the DFT is a sampling of the DTFT (see Sampling_the_DTFT), whose periodicity is obvious by inspection of:
:X_{1/T}(f) = \underbrace{\sum_{k=-\infty}^{\infty} X\left(f - k/T\right)}_{\text{periodic}} = \sum_{n=-\infty}^{\infty} T\cdot x(nT)\ e^{-i 2\pi f T n}
--Bob K (talk) 12:01, 15 April 2013 (UTC)
thread_title:  Proving the DFT is periodic is not helpful 

message: I spotted the following, apparent contradiction at the beginning of the article: first it is stated:
"The Nyquist frequency, ... is ½ of the sampling rate of a *discrete signal* processing system"
Then in the discussion on the distinction between Nyquist rate and frequency in the next paragraph, it is stated that the Nyquist frequency is a property of a continuous-time system, and the Nyquist rate a property of a discrete-time system. 
Since I am no engineer/mathematician, I can't judge whether this is actually a contradiction or whether I'm just missing something; but it is confusing.  — Preceding unsigned comment added by 145.18.213.196 (talk) 11:58, 16 May 2013 (UTC)
replies: text: Read it again.  It does not say "continuous-time system". But I just undid some apparent vandalism (yesterday) that was probably confusing you. --Bob K (talk) 12:30, 16 May 2013 (UTC)
thread_title:  Nyquist rate vs. Nyquist frequency; apparent contradiction 

message: Wouldn't it be better to have this be a Disambiguation page rather than it's current form.  For instance the page on Eagle Eye refers to the "Nyquist Limit" and then links to this page. Or perhaps the title of this section should be changed.  It implies a subheading on other meanings for the phrase Nyquist Frequency.  Also in note 2 it defines what I believe is the term Alias frequency but makes no mention of this term. T S Ballantine (talk) 11:16, 17 May 2015 (UTC)
thread_title:  Other Meanings Suggestion Copyedit (minor) 

message: Seriously? Cycles/inch ?! I thought at least in the scientific world the imperial system got banned? I really hope no one uses units like these in practice anymore.  — Preceding unsigned comment added by 129.132.210.35 (talk) 23:48, 20 July 2015 (UTC)
thread_title:  Cycles/inch ?! 

message: The article should be expanded with information on sampling at the Nyquist frequency. It is a more complex case, as aliasing or folding doesn't occur, but instead the output is highly dependent on the phase difference between the signal and the sampling frequency.JHBonarius (talk) 13:43, 29 January 2018 (UTC)
replies: text: Or just add a WikiLink to Nyquist–Shannon sampling theorem#Critical frequency   --Bob K (talk) 00:55, 30 January 2018 (UTC)
thread_title:  Sampling at Nyquist frequency

message: Hello,
I'm relatively new to editing Wikipedia, so I don't know exactly what to put, but in the Other Meanings section, the phrase "Some later publications, including some respectable textbooks, call twice the signal..." (emphasis mine) which strikes me as very opinionated. I don't know how to properly mark this as such, so I would welcome advice. Thank you. Cormac596 (talk) 16:13, 29 January 2021 (UTC)
thread_title:  Opinionated terms