How to write a program for Pseudo Random Binary sequence in matlab?

i need a program on PRBS

Answer 1

[Walter Roberson]

PRBS = @(N) randi([0 1], 1, N);

This takes one parameter, which is the number of values to generate, and returns a PRBS of that length.

Answer 2

[anu chauhan]

I am doing my research on OFDM in LONG HAUL COMMUNICATION and made a program but when i am varying its values i am not able to obtain the results can you help me regarding improvising the new values i am attaching the program

clear all;
clc;
clf;
cputime;
tic;
%--------------------------USER INPUTS-----------------------
total_length=40; % ENTER IN KM
numberbits=4; % ENTER (if changing this change nobits)
nobit = [1 0 1 1]; % ENTER (consider numberbits)
%------------------------------------------------------------
%-----------------------SMF Characteristics------------------
gamma=0.31; %Non-linear coefficient of SMF
alpha=0.2;%Attenuation of SMF (db/km)
beta2=-16e-24; %2nd order GVD of SMF(ps^2/km)
%------------------------------------------------------------
i=sqrt(-1);
Po=0.517; %Input Power
Ao=sqrt(Po); %Amplitude
PPo=0.00012;
AAo=sqrt(PPo);
n=8192;
to=10e-12; %Initial Pulse Width in second (10ps)
dt=10e-15; %Ten femto-seconds, difference between 2 consecutive samples
pi=3.1415926535;
Ld=(to^2)/(abs(beta2)); %Dispersion length
Ln=1/(gamma*Po); %Nonlinear length
N=Ld/Ln;
h=0.1; %in km
tp=n*dt;
tt=tp/2;
step_size=2*h;
L=total_length/step_size;
%--------------Defining tau2 for the numberbits--------------
new=n*numberbits;
tp1=dt*new;
tt1=tp1/2;
for j=1:1:new
t1(j)=-tt1+((j-1)*((2*tt1)/new));
tau2(j)=t1(j)/to;
end;
%------------------------------------------------------------
%-----------------------Gaussian wave------------------------
for j=1:1:n
t(j)=-tt+((j-1)*((2*tt)/n));
tau(j)=t(j)/to;
f(j)=Ao*exp(-tau(j).^2);
end;
%------------------------------------------------------------
%------------------------Zerowave----------------------------
for j=1:1:n
t(j)=-tt+((j-1)*((2*tt)/n));
tau(j)=t(j)/to;
zerowave(j)=AAo*exp(-tau(j).^2);
end;
%------------------------------------------------------------
%-----------------------calculating w -----------------------
wp=1/(2*tt);
for j=1:1:n
    if j<(n/2)
w(j)=2*pi*wp*(j-1);
else
w(j)=2*pi*wp*(j-(n+1));
end;
end;
%------------------------------------------------------------
q8=f;
qq8=zerowave;
%-----------------------------SMF----------------------------
%for 1
zz=1;
for k=1:1:L;
q1=fft(q8);
q2=q1.*exp(((-alpha/2)+i*(beta2/2)*(w.^2))*(h/2));
q3=ifft(q2);
q4=q3.*exp(i*gamma*(abs(q3).^2)*h);
q5=fft(q4);
q6=q5.*exp(((-alpha/2)+i*(beta2/2)*(w.^2))*(h/2));
q7=ifft(q6);
q8=q7;
figure(1), plot (tau, f, tau, q8);
xlabel('Time (tau)');
ylabel('Amplitude');
hleg1 = legend('Input Gaussian Wave','SMF O/P');
grid on;
q8dummy(zz,:)=abs(q8);
zz=zz+1;
k;
end;
zz=zz-1;
figure(2), mesh(q8dummy(1:1:zz,:));
xlabel('Time');
ylabel('Distance*200(m)');
zlabel('Amplitude');
%for 0
zz=1;
for k=1:1:L;
qq1=fft(qq8);
qq2=qq1.*exp(((-alpha/2)+i*(beta2/2)*(w.^2))*(h/2));
qq3=ifft(qq2);
qq4=qq3.*exp(i*gamma*(abs(qq3).^2)*h);
qq5=fft(qq4);
qq6=qq5.*exp(((-alpha/2)+i*(beta2/2)*(w.^2))*(h/2));
qq7=ifft(qq6);
qq8=qq7;
zerowavedummy(zz,:)=abs(qq8);
zz=zz+1;
k;
end;
zz=zz-1;
%--------------------Concatenating the bits------------------
x=[];
x1=[];
x3=[];
for p=1:1:numberbits
if nobit(p)==1
x=[x f]; %initial input
x1=[x1 q8]; %after EDFA (Final)
x3=[x3 q8dummy];
else
x=[x zerowave];
x1=[x1 qq8];
x3=[x3 zerowavedummy];
end;
p;
end;
%------------------------------------------------------------
figure(3), plot (tau2, x, tau2, x1);
xlabel('Time (tau)');
ylabel('Amplitude');
hleg1 = legend('Input Bit Sequence','SMF O/P');
grid on;
figure(4), mesh(x3(1:1:zz,:));
xlabel('Time');
ylabel('Distance*200(m)');
zlabel('Amplitude');
%------------------------------------------------------------
toc;
cputime=toc;
disp('CPU time:'), disp(cputime);

[Walter Roberson]

When you are varying which values, you are not able to obtain what results?

I do not see any use of PRBS in this code, so it would appear to be a completely new Question rather than a follow-on question.