Talk:High-pass filter

message: I have added the High Pass Filter Image, however am not sure how to scale it, anyone feel free to do so. — Preceding unsigned comment added by Dragoljub (talk • contribs) 03:08, 15 November 2004 (UTC)
thread_title:  High-pass filter image 

message: I have edited the formula for alpha in the code section.  —Preceding unsigned comment added by 194.138.39.53 (talk) 09:59, 15 April 2008 (UTC)
thread_title:  Alpha code 

message: With the given equations, if the time interval is the same as the RC time constant, alpha calculates as 0.5.  But this is incorrect, after one time constant of time the output should reduce to 1/e, not 1/2.  Surely the correct equation is e^(-dt/RC).
Richard whitehead (talk) 20:48, 13 June 2008 (UTC)
replies: text: That depends on how you choose to discretize the continuous-time filter.  I think your method probably corresponds to the impulse invariance method, but that's not the only sensible choice. Dicklyon (talk) 21:11, 13 June 2008 (UTC)
replies: text: I didn't realise I was being that clever!  I just imagined the input signal varying as a sequence of steps.  In this case, the current decays between steps according to exponential decay, and then a new lot of current is added on when the step happens (both ends of the capacitor changing voltages by the same amount because the step is instantaneous, so the new current is delta-V / R).  I expect the result is very similar unless the simulation time step is too long (too similar to RC).  Richard whitehead (talk) 13:09, 14 June 2008 (UTC)
replies: text: See the new comments about the relationship between α and RC. As you can see, the decay truly is exponential, but the mapping from "continuous-time frequencies" to "discrete-time frequencies" is not linear, and so the "time constant" isn't going to match especially for α that large. Keep in mind that whenever you go from CT to DT, you're wrapping an infinite line (i.e., from 0 Hz to ∞ Hz) to a finite line (i.e., the semicircular circumference from 0 radians/sample to π radians/sample). There's no way to do that linearly, and so the frequencies only "match" in a small region. That's why we have different CT-to-DT methods; sometimes we need them to match in different ways. For example, we might need to make sure all CT poles land inside the unit circle, or we might need to make sure that the match is very close near the corner frequency... or lots of other things. There's always going to be mismatch, and that's why it's always best to do your design in your target context. If it's going to be realized in discrete-time, it should be designed there too. —TedPavlic (talk) 20:46, 8 January 2009 (UTC)

text: One more thing. As you can see on the new sections of the page, this method approximates the derivative by taking the slope over one sampling period. Each CT-to-DT method approximates the derivative in a different way. Put another way, each CT-to-DT method deals with the space "in between" samples in different ways. As you can see, there are tradeoffs. Lots of people like approximating the derivative as the slope between time points. A consequence of that is that your impulse response doesn't have the same time constant (however, there is a qualitative relationship between the DT and CT time constants; as one gets bigger, so does the other). —TedPavlic (talk) 21:17, 8 January 2009 (UTC)
thread_title:  Computer algorithm 

message: The title of this article is high-pass filter.  You can implement a discrete-time high-pass filter without attempting to match the characteristics of any particular continuous time high-pass filter. So the emphasis on matching the 1st-order continuous time version seems misplaced to me.Ccrrccrr (talk) 17:03, 28 May 2009 (UTC)
replies: text: See recent changes (as a start). —TedPavlic (talk) 23:04, 28 May 2009 (UTC)
replies: text: Nice!  Thanks.  The article is still a bit of an odd collection of facts but you fixed the worst of it very nicely.Ccrrccrr (talk) 11:54, 29 May 2009 (UTC)
thread_title:  High-pass vs. 1st order LTI high-pass 

message: I'd like to see a summary for less technical people.
It would be nice to include a sample audio clip showing what something sounds like before and after a high pass filter is applied.
Kevink707 (talk) 18:44, 5 February 2010 (UTC)
thread_title:  More information for non-experts 

message: Hello fellow Wikipedians,
I have just modified 3 external links on High-pass filter. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added archive https://web.archive.org/web/20110715123934/http://recforums.prosoundweb.com/index.php/m/462291/0/ to http://recforums.prosoundweb.com/index.php/m/462291/0/
*Added archive https://web.archive.org/web/20100103130925/http://crownaudio.com/pdf/amps/128313.pdf to http://www.crownaudio.com/pdf/amps/128313.pdf
*Added archive https://web.archive.org/web/20100209153528/http://media.qscaudio.com/pdfs/plxuser.pdf to http://media.qscaudio.com/pdfs/plxuser.pdf
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
Cheers.—InternetArchiveBot (Report bug) 03:31, 2 April 2017 (UTC)
thread_title:  External links modified 

message: Please add a section covering resonance.  Also, please explain the difference between a single-pole filter and a 2-pole filter (is the latter simply two of the former in series?)  174.106.34.169 (talk) 14:11, 26 January 2023 (UTC)
thread_title:  Requests for more information