Talk:Minimum phase

message: It is expected that any person reading this article will understand why is this property called "minimum phase". Stable zeros, cauzality, and all the other properties written until now in the article do not motivate why and how comes in the "minimum phase" claim. The article must explain how is the "phase" come into discussion, how is the "minimum" established and why exactly is this particular minim phase property relevant practically.   
:  this article is confusing to beginners. Any transfer function has amplitude and phase. Given only the amplitude response, that amplitude could be modeled with a function that does not have zeroes in the right-half-plane.  IF the phase is ALSO then matched, the original function is minimum phase.  IF NOT, and additional function called an 'all-pass network' is cascaded to match the phase. This implies the original function is non-minimum-phase, because an 'all-pass' just adds phase CorvetteZ51 (talk) 09:18, 16 July 2015 (UTC)
thread_title: A wish

message: Sorry, but the first sentence of the article is wrong:
   In control theory and signal processing, a linear, 
   time-invariant system is minimum-phase if the system
   and its inverse are causal and stable.
Instead, in control theory an LTI system is minimum-phase if
it has stable zeros (or alternatively, if the inverse is stable).
The definition is NOT coupled to "causal" nor to "stability" of
the system. 
MartinOtter 19:53, 3 February 2007 (UTC)
replies: text: What is your source?  The page is consistent with the definitions given at <http://ccrma.stanford.edu/~jos/filters/Definition_Minimum_Phase_Filters.html>. LachlanA (talk) 16:37, 18 May 2008 (UTC)

text: I'm confused about maximum phase definition. Quoting Manolakis, Ingle, Kogon - Statistical and Adaptive Signal Processing (2005):
   (...) In an analogous manner, we can define a maximum-phase system as one in which both the
   system and its inverse are anticausal and stable. A PZ system then is maximum-phase
   if all its poles and zeros are outside the unit circle. (...)
----  —Preceding unsigned comment added by 200.193.3.224 (talk) 04:10, 5 June 2008 (UTC)
thread_title:  Error in article: in control theory, minimum phase systems might be unstable 

message: The examples given (the ones that correspond to the complex plane figures) do not appear to be causal (i.e., they have more zeros than poles), which means that they aren't stable in the useful sense. For example, the noncausal system:
:\frac{s^2}{s+5}
has a pole at s=\infty. The reason why textbooks define minimum phase systems as causal/stable systems with inverses that are also causal/stable is that that guarantees that you count all of your implicit and explicit poles. —TedPavlic | (talk) 00:29, 30 December 2008 (UTC)
thread_title:  Some of the examples are not causal 

message: I think that there are too much of the same links to other wiki pages. In the section Minimum_phase_as_minimum_group_delay alone I've counted 7 links to group delay, 7 to zero(s), 4 to transfer function and another 4 to unit circle. There are a lot more duplicated links like these on the entire page. I'm still a bit new to wiki, so I'm just stating it here. --Gligoran (talk) 09:18, 13 February 2010 (UTC)
thread_title:  Too much of the same links to wiki pages 

message: The current version of the section "Minimum phase as minimum group delay" starts with the statement:
"For all causal and stable systems that have the same magnitude response, the minimum phase system has the minimum group delay."
After some manipulations, which in themselves I can follow, there is the statement:
"The denominator and \theta_a are invariant to reflecting the zero a outside of the unit circle, i.e., replacing a with (a^{-1})^{*}."
I wonder, could anyone explain why one would like to substitute a with its (complex conjugate) inverse? I fail to see how this would preserve the magnitude response (which I understand to be the modulus of the system response). Specifically:
\left| 1 - a z^{-1} \right| \neq \left| 1 - (a^{-1})^{*} z^{-1} \right|.
Or am I mistaken? On a more fundamental level, the article could do with a(n even) more conceptual explanation about minimum-phase(d)ness, or at least I would appreciate that.Redav (talk) 10:40, 19 July 2020 (UTC)
thread_title:  Reason for replacing zero <math>a</math> with zero <math>(a^{-1})^{*}</math>?