Summary

DescriptionAm2 spec.gif	English: animated picture showing the spectrum of an amplitude-modulated transmitter. case-1: Frequency changes. case-2: Amplitude changes. MATLAB code
Date	24 January 2013
Source	programmed by myself
Author	Herbertweidner (talk) 12:16, 25 January 2013 (UTC)
Permission (Reusing this file)	Public domainPublic domainfalsefalse This work has been released into the public domain by its author, Herbertweidner (talk). This applies worldwide. In some countries this may not be legally possible; if so: Herbertweidner (talk) grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

filename = 'am2_spek.gif'; %MATLAB code
steps     = 39;      % no of different frames 
speed     = 0.01;    % Delay in sec between frames. (Parameter passed to gif-file)
x_med = (0 : 0.001 : 2); 
axis tight; %axis([0 3 -2 2]);
% gcf is handle "current figure"
set(gcf,'nextplot','replacechildren', 'visible','off');
[im,map] = rgb2ind(f.cdata,256,'nodither'); 
freq = 3; % tiefste Frequenz
for schritt=1:steps %zuerst Frequenz ändern
 freq=freq-sign(schritt-steps/2-1);
 ton = sin(freq* 2*pi * x_med ); hold off;
 fill([0 3 3 0],[-1.5 -1.5 1.5 1.5],'w'); hold on;
 plot(x_med, ton);
 line([0,2.1], [0,0], 'Color',[0 0 0]); %Basis links
 line([2.1,2.05], [0,-.05], 'Color',[0 0 0]);
 line([2.1,2.05], [0,.05], 'Color',[0 0 0]);
 text(1,.2,'Time', 'Color',[0 0 0]) 
 line([2.1,2.9], [-1,-1], 'Color',[0 0 0]); %Basis rechts
 line([2.9,2.85], [-1,-.95], 'Color',[0 0 0]);
 line([2.9,2.85], [-1,-1.05], 'Color',[0 0 0]);
 text(2.3,-1.2,'Frequency', 'Color',[0 0 0]) 
 line([2.5,2.5],[-1,1], 'Color',[1 0 0]); %Träger
 text(2.6,0.9,'Carrier', 'Color',[1 0 0]) 
 delta=0.53*freq/steps;
 line([2.5+delta,2.5+delta],[-1,0], 'Color',[0 0.9 0]); %USB
 text(2.6,.3,'USB', 'Color',[0 0.9 0]) 
 line([2.5-delta,2.5-delta],[-1,0], 'Color',[0 0.9 0]); %LSB
 text(2.2,.3,'LSB', 'Color',[0 0.9 0]) 
 f = getframe(); % get hardcopy
 im(:,:,1,schritt) = rgb2ind(f.cdata,map,'nodither'); % store to im
end
 fc=schritt+1; %frame counter
for schritt=0:steps-2 %nun Amplitude ändern
 ampl=(cos(schritt*pi/steps))^2;
 ton = ampl*sin(freq* 2*pi * x_med ); 
 hold off;
 fill([0 3 3 0],[-1.5 -1.5 1.5 1.5],'w'); hold on;
 plot(x_med, ton);
 line([0,2.1], [0,0], 'Color',[0 0 0]); %Basis links
 line([2.1,2.05], [0,-.05], 'Color',[0 0 0]);
 line([2.1,2.05], [0,.05], 'Color',[0 0 0]);
 text(1,.2,'Time', 'Color',[0 0 0]) 
 line([2.1,2.9], [-1,-1], 'Color',[0 0 0]); %Basis rechts
 line([2.9,2.85], [-1,-.95], 'Color',[0 0 0]);
 line([2.9,2.85], [-1,-1.05], 'Color',[0 0 0]);
 text(2.3,-1.2,'Frequency', 'Color',[0 0 0]) 
 line([2.5,2.5],[-1,1], 'Color',[1 0 0]); %Träger
 text(2.6,0.9,'Carrier', 'Color',[1 0 0]) 
 line([2.5+delta,2.5+delta],[-1,-1+ampl], 'Color',[0 0.9 0]); %USB
 text(2.6,.3,'USB', 'Color',[0 0.9 0]) 
 line([2.5-delta,2.5-delta],[-1,-1+ampl], 'Color',[0 0.9 0]); %LSB
 text(2.2,.3,'LSB', 'Color',[0 0.9 0]) 
 f = getframe(); % get hardcopy
 im(:,:,1,fc) = rgb2ind(f.cdata,map,'nodither'); % store to im
 fc=fc+1;
end
% write animation to file
imwrite(im, map, filename, 'DelayTime',speed, 'LoopCount',inf)
%end

Licensing

I, the copyright holder of this work, hereby publish it under the following license:

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The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission. http://creativecommons.org/publicdomain/zero/1.0/deed.enCC0Creative Commons Zero, Public Domain Dedicationfalsefalse