Talk:Chebyshev filter

message: are chebyshev filters the same as IIS filters?
is the comb filter a sort of chebyshev filter?
does the chebyshev filter work with delayed signal input from its output?
what is the chebyshev filter actually good for? (applications)
--Abdull 17:58, 18 Jun 2005 (UTC)
replies: text: As can be seen from the equation on the article page, the poles can be thought of as uniformly distributed on a circle, and this circle then stretched in each dimension to give an ellipse. Oli Filth 22:35, 10 November 2006 (UTC)
thread_title: Untitled

message: Yo I added this section but someone please check for validity. I am not a EE major (I'm in aerospace) but I gleaned the equations off of the 2nd reference on the bottom (which I also added). If someone could check it out for accuracy, etc., that'd be great 
Subheight640 15:37, 27 July 2007 (UTC)
thread_title:  New LC realization section 

message: There is beauty in the Chebyshev filter but if you read this article you wouldn't know it. I don't have a clue how to manipulate the math graphics, but if I did I could create a much more clear explanation. Basically you want to substitute arcsinh(1/e) with a constant variable, say 'a'. Then you split up the real and imaginary parts of the pole locations into x and y respectively. Then you can show how (x/sinh(a))^2 + (y/cosh(a))^2 = 1. This equation clearly shows that the chebyshev poles are on an ellipse. It can then be compared to the Butterworth filter which has its poles on a circle.
In the Chebyshev filter, the terms roll-off is not defined properly and also the link with it shows the wrong meaning.  —Preceding unsigned comment added by 115.187.16.1 (talk) 05:37, 5 April 2009 (UTC)
replies: text: It has been on my to do list for a long time to write a roll-off article.  I will get round to it one day.  If you want a tutorial on the math markup take a look at Help:Displaying a formula. SpinningSpark 13:45, 11 April 2009 (UTC)
thread_title:  Poor Explanation... 

message: Hey,
I am a little confused about the picture of the frequency response of the chebychev filter type 1.
If you plot the response in dB it is impossible that the blue line is 1 / sqrt( 1 + eps^2), because it is clearly a positive value.
It looks like the scale of the gain isn't in dB, but in the "normal" absolute value of the transfer function. Maybe it should be chanced.
91.66.179.181 (talk) 12:06, 30 August 2012 (UTC)
replies: text: The blue line is the gain in dB for G=1/√2 with G as defined in the text.  It is not the actual value  of the blue line plot, which is -3 dB.  The graph is definitely in dB; if it were linear the excursions would be considerably more pronounced. 16:25, 30 August 2012 (UTC)
thread_title:  Missleading picture 

message: Why do the gain images show twice the number of poles and zeros compared to the transfer function? All poles and zeros appear duplicated with the sign of the real part of the duplicate flipped. Olli Niemitalo (talk) 08:55, 30 October 2016 (UTC)
replies: text: The answer is not simple. The gain is not simply the absolute value of the transfer function (I have changed that statement in the article). The gain function is the absolute value of the steady-state output amplitude divided by the amplitude of a steady-state input. So if you want to calculate the gain using the transfer function, you input a signal for which σ is zero, get the output signal, which, as time increases, may settle into a steady state, then you divide those steady-state amplitudes and take the absolute value. It is a theorem that the result you get will be the absolute value of the transfer function evaluated at j ω. The output will only settle to a steady state if the poles of the transfer function all  have σ less than zero. The gain function poles will be the poles of the transfer function, AND the mirror images of the poles of the transfer function, with the ω axis forming the mirror. In other words if σ+ j ω is a pole of the transfer function, then both σ+ j ω and -σ+ j ω will be poles of the gain function. PAR (talk) 15:25, 2 November 2016 (UTC)
thread_title:  Gain on complex plane images 

message: Could a section on generalised Chebyshev, a.k.a "quasi-elliptical", filters could be added to this article, please?  MyOtherHead (talk) 01:52, 17 May 2017 (UTC)
thread_title:  Generalised Chebyshev Filters 

message: In the first chapter "Type I Chebyshev filters (Chebyshev filters)" δ stands for the passband ripple in dB, while in the later chapter "Implementation" it's called R. This could be because of different literature, but it should be consistent.
: WP:SOFIXIT. SpinningSpark 17:33, 11 January 2019 (UTC)
thread_title: Consistency