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% Convolution of NRZ rectangular pulses 
 
function convnrz(action) 
 
 
if (nargin<1) 
  action = 'start'; 
end; 
 
if strcmp(action,'start') 
 
	aufloesung = 200; 
	laenge = 2; 
 
	x1 = linspace(-laenge,laenge,aufloesung); 
	g1 = 0.5*(sign(x1+0.5)-sign(x1-0.5)); 
 
	%Faltung  
 
	c = conv(g1,g1);  
 
	rng = -2 * x1(1);       % maximum length of axis symmetric 
	anz = (length(c)-1)/2;  % number of axis labels to each side 
 
	c = c ./ (anz/rng);     % amplitude correction 
 
	x2 = zeros(size(c));    % compute x axis coordinates 
	for k=1 : length(c) 
	  x2(k) = (k-anz)*rng/anz; 
	end; 
 
end; 
 
 
if strcmp(action,'start') 
 
	set(0,'Units','pixels'); 
	scnsize = get(0,'ScreenSize'); 
 
	% open window 
	 
	figure ('Position', [0.25*scnsize(3)   0.15*scnsize(4)   0.7*scnsize(3)   0.7*scnsize(4)], ... 
		'Name', 'Convolution of NRZ Rectangular Pulses', ... 
		'Tag', 'ConvNRZRechteck', ... 
		'NumberTitle','off' ... 
		); 
 
	set(gcf,'DefaultTextColor','m'); 
 
	backcolor = get(gcf,'Color'); 
 
 
 
 
	% ------------------------------ 
	% Plot 1: NRZ rectangular pulse 
	% ------------------------------ 
	 
	subplot(2,2,1), plot(x1,g1,'EraseMode','background') 
 
	title('NRZ Rectangular Pulse')  
	xlabel('t/T') 
	ylabel('g(t/T)') 
	set(gca,'Tag','ConvNRZPlot1'); 
 
	pos1 = get(gca, 'Position'); 
	set(gca,'Position',[pos1(1)-.1/2*pos1(3) pos1(2) 1.1*pos1(3) pos1(4)]); 
	pos1 = get(gca, 'Position'); 
 
	set(gca,'YLimMode','manual'); 
	set(gca,'YLim',[-.25 1.25]); 
 
	set(gca,'XTick', [-5 :1: 5]); 
	grid 
 
 
	% ------------------------------ 
	% Plot 2: NRZ rectangular pulse 
	% ------------------------------ 
	 
	subplot(2,2,2), plot(x1,g1,'EraseMode','background') 
	title('NRZ Rectangular Pulse')  
	xlabel('t/T') 
	 
	set(gca,'Tag','ConvNRZPlot2'); 
 
	pos2 = get(gca, 'Position'); 
	set(gca,'Position',[pos2(1)-.1/2*pos1(3) pos2(2) 1.1*pos2(3) pos2(4)]); 
	pos2 = get(gca, 'Position'); 
 
	set(gca,'YLimMode','manual'); 
	set(gca,'YLim',[-.25 1.25]); 
 
	set(gca,'XTick', -5: 1 : 5); 
	grid 
 
 
 
 
	% ------------------ 
	% Convolution  
	% ------------------ 
 
	text = uicontrol(gcf, ... 
		'Style', 'text', ... 
        'Units', 'normalized', ... 
		'Position', [pos1(1)+pos1(3)+0.005, pos1(2)+pos1(4)/2-.15/2, (pos2(1)-pos1(1)-pos1(3))-0.005, .15], ... 
		'FontSize', 30, ... 
		'BackgroundColor', backcolor, ... 
		'ForegroundColor', 'm', ... 
		'String', '*' ... 
		); 
 
	% ------------------------------------------------------- 
	% Plot 3: convolution of NRZ rectangular pulses 
	% ------------------------------------------------------- 
 
	subplot(2,2,3), plot(x2,c,'EraseMode','background') 
	title('Result of Convolution')  
	xlabel('t/T') 
	ylabel('g(t/T)') 
	set(gca,'Tag','ConvNRZProdukt'); 
 
	pos3 = get(gca, 'Position'); 
	set(gca,'Position',[pos1(1) pos3(2) pos1(3)+pos2(3)+(pos2(1)-pos1(1)-pos1(3)) pos3(4)]); 
	set(gcf,'DefaultTextColor','m') 
 
	set(gca,'XLimMode','manual'); 
	set(gca,'XLim',[-rng rng]); 
	set(gca,'YLimMode','manual'); 
	set(gca,'YLim',[-0.25 1.25]); 
 
	set(gca,'XTick', -10: 1 : 10); 
	grid 
 
end; 
 
clear action;