1. Communicatio
n optique
Compte rendu TP1
TOUATI KARIM / IMI 4 /Groupe E

2. compte rendu
communication optique
modulation d'amplitude
>> fs=100;
>> t=[0:2*fs+1]'/fs;
>> fc=10;
>> x=sin(2*pi*t);
>> ydouble=ammod(x,fc,fs);
>> zdouble=fft(ydouble);
>> zdouble=abs(zdouble(1:length(zdouble)/2+1));
>> subplot(2,1,1);
>> frqdouble=[0:length(zdouble)-1]*fs/length(zdouble)/2;
>> title('spectrum of double side-bandsignal');
>> plot(frqdouble,zdouble);
>> subplot(2,1,1);
>> ydouble=ammod(x,fc,fs,0,1);
>> plot(frqdouble,zdouble);
>> subplot(2,1,1);
>> ydouble=ammod(x,fc,fs,0,1);
>> zdouble=fft(ydouble);
>> zdouble=abs(zdouble(1:length(zdouble)/2+1));
>> subplot(2,1,1);
>> frqdouble=[0:length(zdouble)-1]*fs/length(zdouble)/2;
>> title('spectrum of double side-bandsignal');
>> plot(frqdouble,zdouble);
>> ydouble=ssbmod(x,fc,fs);
>> zdouble=fft(ydouble);
>> zdouble=abs(zdouble(1:length(zdouble)/2+1));
>> subplot(2,1,1);
>> frqdouble=[0:length(zdouble)-1]*fs/length(zdouble)/2;
>> plot(frqdouble,zdouble);
>> ydouble=ssbmod(x,fc,fs,1,'upper');
>> zdouble=fft(ydouble);
>> zdouble=abs(zdouble(1:length(zdouble)/2+1));
>> subplot(2,1,1);
>> frqdouble=[0:length(zdouble)-1]*fs/length(zdouble)/2;
>> plot(frqdouble,zdouble);
2

3. Aprés la modulation le signal est translaté autour de Fc:
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plot(t,x,t,ydouble);
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-1
-1.5
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4. modulation de fréquence d'un signal
fs=8000;
>> fc=3000;
>> t=[0:50:fs]'/fs;
>> s1=sin(2*pi*300*t)+2*sin(2*pi*600*t);
>> s2=sin(2*pi*150*t)+2*sin(2*pi*900*t);
>> x=[s1,s2];
>> dev=50;
>> y=fmmod(x,fc,fs,dev);
>> z=fmdemod(y,fc,fs,dev);
>> figure(1),plot(y);title
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-0.5
-1
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5. figure(2),plot(z);tilte
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m=16;
>> k=log2(m);
>> n=3e4;
>> x=randint(n,1);
>> stem(x(1:40),'filed');
>> stem(x(1:40),'filled');
>> title('random bits');
>> xlabel('bit index');
>> ylabel('binarg value');
>> Nxsym=length(xsym);*
>> xsym=bi2de(reshape(x,k,length(x)/k).','left-msb');
>> Nxsym=length(xsym);
>> title('random symbols');
>> xlabel('symbol index')
>> ylabel('integer value');
>> xlabel('symbol index');
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6. 1
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random symbols
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symbol index
integer value
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7. 1
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random symbols
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symbol index
integer value
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