BPSK Simulation in MATLAB

Actually flicked the program from somewhere in a forum.

Took some time to understand it first. Few months back.

Now i’ve coded it better with some tweaks. So that you understand it sooner than me. 🙂

 

Here’s the code, I’ve copied and changed it to Italics, copy, paste, save and run.
Post your doubts in the comments 

clear all;
close all;

f = 2; %frequency of sine wave
fs = 100; %sampling period of the sine wave
t = 0:1/fs:1; %splitting time into segments of 1/fs
%setting the phase shifts for the different BPSK signals
p1 = 0;
p2 = pi;
%getting the number bits to be modulated
N = input(‘enter the number of bits to be modulated: N = ‘);
%generating the random signal
bit_stream=round(rand(1,N));
%allocating the dynamic variables
time = [];
digital_signal = [];
PSK = [];
carrier_signal = [];

%GENERATING THE SIGNALS
for ii = 1:1:N
%the original digital signal is
if bit_stream(ii) == 0
bit = zeros(1,length(t));
else
bit = ones(1,length(t));
end
% bit0 = (bit_stream(ii)==0)*zeros(1,length(t));
% bit1 = (bit_stream(ii)==1)*ones(1,length(t));
digital_signal = [digital_signal bit];

%Generating the BPSK signal
if bit_stream(ii) == 0
bit = sin(2*pi*f*t+p1);
else
bit = sin(2*pi*f*t+p2);
end
PSK = [PSK bit];

%Generating the carrier wave
carrier = sin(2*f*t*pi);
carrier_signal = [carrier_signal carrier];

time = [time t];
t = t + 1;

end

subplot(3,1,1);
plot(time,digital_signal,’r’);
grid on;
axis([0 time(end) -0.5 1.5]);

subplot(3,1,2);
plot(time,PSK);
grid on;
% axis([0 time(end) -2 2]);
axis tight;

subplot(3,1,3);
plot(time,carrier_signal);
grid on;
axis tight;

 

 

The output should look something like this …