Discussion :

[resotel]

bonjour,

je voudrais simuler un programme MATLAB mais je n'arrive pas à trouver les bons paramètres pour faire fonctionner le programme.

j'ai besoin de votre aide svp.
merci

Code :

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 %Code Matlab
 
clc;
q=1;
Pi=input('Enter the value of input power in mW  ')
alpha=input('Enter the value of fiber loss in db/km  ')
t=input('Enter the value of input pulse width in seconds  ') 
tau=input('Enter time period with upper(U), lower(L) and interval between upper and  lower interval(I) in this format L:I:U')
dt=input('enter intervel of period')
Area=input('Enter the area of effective core in m^2  ')
C=input('Enter the value of chirp factor   ')
Lamda=input('Enter the wavelength in meters   ')
D=input(' Enter the value of dispersion coefficient ps/nm/km   ')
s=input('Enter the length of fiber in Km   ')
disp('Fiber losses in /km   ')
A=alpha/(4.343) 
c=3*1e8;
n1=1.48;
pi=3.1415926535;
%delta=0.01
delta=(n1*2*pi*s)/Lamda
n2=7e-10
n2=n1*(1-delta)
f=c/Lamda;
omega=2*pi*f;
a=n2*omega;
b=c*Area;
gamma=a/b %calculation of nonlinear coefficient
%gamma=0.003;
B2=-(Lamda^2*D)/(2*pi*c) % calculation of group velocity dispersion coefficient
L=(t^2)/(abs(B2)) %dispersion length
 
Ao=sqrt(Pi) % amplitude of an input gaussian pulse
 
 h=2000  % small step as defined by  split step algorithm
 
for ii=0.1:0.1:(s/10) %different fiber lengths
    X=ii*L;
    At=Ao*exp(-((1+i*(C))/2)*(tau/t).^2); % generation of an gaussian input pulse
    figure(1)
    plot(abs(At)); % graph of input pulse
    title('Input Pulse'); xlabel('Time in ps'); ylabel('Amplitude');
    grid on;
    hold off;
    l=max(size(At));  
 
    fwhmi=find(abs(At)>abs(max(At)/2));
    fwhmi=length(fwhmi);
    dw=1/l/dt*2*pi;
    w=(-1*l/2:1:l/2-1)*dw;
    At=fftshift(At);
    w=fftshift(w);
    spec=fft(fftshift(At)); %generating a pulse spectrum
    for j=h:h:X
        spec=spec.*exp(-A*(h/2)+i*B2/2*w.^2*(h)) ; % calculation of linear part of NLSE 
        f=ifft(spec);
        f=f.*exp(i*gamma*((abs(f)).^2)*(h)); %calculating nonlinear part of NLSE
        spec=fft(f);
        spec=spec.*exp(-A*(h/2)+i*B2/2*w.^2*(h)) ; % NLSE calculation
    end
    f=ifft(spec); % pulse propagation
    output_pulse(q,:)=abs(f); %preserving output pulse
    fwhmo=find(abs(f)>abs(max(f)/2));
    fwhmo=length(fwhmo);% finding the Full width half maximumof output signal
    pbratio(q)=fwhmo/fwhmi; %finding pulse brodening ratio
    q=q+1;
end
figure(2);
mesh(output_pulse(1:1:q-1,:)); %output spectrum
title('Pulse Evolution');
xlabel('Time'); ylabel('distance in km'); zlabel('amplitude');
figure(3)
plot(pbratio(1:1:q-1)); %pulse broadening plot
xlabel('distance in km');
ylabel('Pulse broadening ratio');
grid on;
hold on;
 
 
 
 
%Calcul du BER.
 
 
Q=input('enter the value of Q factor in db');
Pi=3.14
A=(1/2*Pi)
B=exp(-Q^2/2)
disp('The BER for value of Q is')
BER=A*(B/Q)