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Analog Filter Design Toolbox

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Analog Filter Design Toolbox

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27 Dec 2005 (Updated )

GUI to design and simulate active (opamp) LP and HP Bessel, Butter, Cheby, and Elliptic filters.

MenuAnalyzePoleZeroPlot
function MenuAnalyzePoleZeroPlot
% MenuAnalyzePoleZeroPlot is a subfile of the AnalogFilter GUI collection
%
% James C. Squire, 2002
% Assistant Professor, Virginia Military Institute
% ver 1.0

% MenuAnalyzePoleZeroPlot opens a plot of the current filter's poles and zeros

global strFilterObject

% find the roots
strFilterObject=Utility_zpk(strFilterObject);
p = strFilterObject.vPoles;
z = strFilterObject.vZeros;
k1 = strFilterObject.fK1;
p1 = strFilterObject.vPoles1;
z1 = strFilterObject.vZeros1;

sTitle=strFilterObject.sTitle;

% set up plot
figure('menubar','none','toolbar','none','Name',sTitle,'Numbertitle','off')

% plot it
if isempty(k1)
    if ~isempty(z)
        plot(real(p),imag(p),'kx',real(z),imag(z),'ko','markersize',15,'linewidth',1.5)
    else
        plot(real(p),imag(p),'kx','markersize',15,'linewidth',1.5)
    end
else
    if ~isempty(z)
        plot(real(p),imag(p),'kx',real(z),imag(z),'ko',real(p1),imag(p1),'bx',real(z1),imag(z1),'bo','markersize',15,'linewidth',1.5)
    else
        plot(real(p),imag(p),'kx',real(p1),imag(p1),'bx','markersize',15,'linewidth',1.5)
    end
end
axis('equal');

% add labels and origin lines
xlabel('Real Axis'), ylabel('Imaginary Axis')
hold on
axlim=axis;
plot([0 0],axlim(3:4),'g:',axlim(1:2),[0 0],'g:','linewidth',1)
axlim=axis;
axis(axlim*(1+eps)) % weird Matlab bug will sometimes cut off one of the X's marking the poles as being outside the plot area (perhaps because of the size of the marker)
plot([0 0],axlim(3:4),'g:',axlim(1:2),[0 0],'g:','linewidth',1) % weird Matlab bug requires a double-plot sometimes
title(strFilterObject.sTitle)
% add legend if needed
if ~isempty(k1)
    h=plot(0,0,'k',0,0,'b','linewidth',10);  % get a handle to a black and blue line
    legend(h,'ideal components','actual R/C values')
end
figure(gcf)



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