clear all
close all
clc
tic

L=10; %[m] Fiber length
PS=1;
n=1.45;
eps0=8.854e-12; % [F/m] Vacuum permittivity
mu0 = 4*pi*1e-7;%[H/m] Vacuum permeability
c=2.9979e8; % [m/sec] Speed of light
Z0=sqrt(mu0/eps0); %[Ohm] Vacuum impedance
dt = 6e-12; dz=dt*c/n; %Spacial and Temporal step sizes.
%dz=2.5e-4;
Fs=1/dt;

N=round(L/dz); % Fiber length discretization

T=10*2*L*n/c; %time taken for 10 round trips
Nt=round(T/dt);
%% material characteristics

A=80e-12; %[m^2] fiber’s effective area

I1_0=PS/A;

% figure;
FA=(-Nt/2:Nt/2-1)*Fs/Nt;

fc=3e9;
X = randn(1,Nt); %random noise generation
Y1 = 10*lowpass(X, fc, Fs, Steepness=0.8);

ypm1 = 1.2743e+06*exp(1i*Y1);
figure;
plot(FA,abs(fftshift(fft(Y1/Nt))));
xlim([-20e9 20

e9]);
figure;
semilogy(FA,(2*n*c*eps0*A*abs(fftshift(fft(ypm1/Nt).^2))))

I am trying to generate White noise source for my phase modulation technique.
The procedure is to pass the signal through a rectangular band filter to imprint the sinc envelope onto the waveform.
Likewise I have generated random noise and passed through low pass filter of 3GHz but the fft of the product is not upto the figure.
Can anyone suggest any changes.clear all
close all
clc
tic

L=10; %[m] Fiber length
PS=1;
n=1.45;
eps0=8.854e-12; % [F/m] Vacuum permittivity
mu0 = 4*pi*1e-7;%[H/m] Vacuum permeability
c=2.9979e8; % [m/sec] Speed of light
Z0=sqrt(mu0/eps0); %[Ohm] Vacuum impedance
dt = 6e-12; dz=dt*c/n; %Spacial and Temporal step sizes.
%dz=2.5e-4;
Fs=1/dt;

N=round(L/dz); % Fiber length discretization

T=10*2*L*n/c; %time taken for 10 round trips
Nt=round(T/dt);
%% material characteristics

A=80e-12; %[m^2] fiber’s effective area

I1_0=PS/A;

% figure;
FA=(-Nt/2:Nt/2-1)*Fs/Nt;

fc=3e9;
X = randn(1,Nt); %random noise generation
Y1 = 10*lowpass(X, fc, Fs, Steepness=0.8);

ypm1 = 1.2743e+06*exp(1i*Y1);
figure;
plot(FA,abs(fftshift(fft(Y1/Nt))));
xlim([-20e9 20

e9]);
figure;
semilogy(FA,(2*n*c*eps0*A*abs(fftshift(fft(ypm1/Nt).^2))))

I am trying to generate White noise source for my phase modulation technique.
The procedure is to pass the signal through a rectangular band filter to imprint the sinc envelope onto the waveform.
Likewise I have generated random noise and passed through low pass filter of 3GHz but the fft of the product is not upto the figure.
Can anyone suggest any changes. clear all
close all
clc
tic

L=10; %[m] Fiber length
PS=1;
n=1.45;
eps0=8.854e-12; % [F/m] Vacuum permittivity
mu0 = 4*pi*1e-7;%[H/m] Vacuum permeability
c=2.9979e8; % [m/sec] Speed of light
Z0=sqrt(mu0/eps0); %[Ohm] Vacuum impedance
dt = 6e-12; dz=dt*c/n; %Spacial and Temporal step sizes.
%dz=2.5e-4;
Fs=1/dt;

N=round(L/dz); % Fiber length discretization

T=10*2*L*n/c; %time taken for 10 round trips
Nt=round(T/dt);
%% material characteristics

A=80e-12; %[m^2] fiber’s effective area

I1_0=PS/A;

% figure;
FA=(-Nt/2:Nt/2-1)*Fs/Nt;

fc=3e9;
X = randn(1,Nt); %random noise generation
Y1 = 10*lowpass(X, fc, Fs, Steepness=0.8);

ypm1 = 1.2743e+06*exp(1i*Y1);
figure;
plot(FA,abs(fftshift(fft(Y1/Nt))));
xlim([-20e9 20

e9]);
figure;
semilogy(FA,(2*n*c*eps0*A*abs(fftshift(fft(ypm1/Nt).^2))))

I am trying to generate White noise source for my phase modulation technique.
The procedure is to pass the signal through a rectangular band filter to imprint the sinc envelope onto the waveform.
Likewise I have generated random noise and passed through low pass filter of 3GHz but the fft of the product is not upto the figure.
Can anyone suggest any changes. wns, fft, sinc MATLAB Answers — New Questions

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