Question

7.13) Repeat Problem 7.11 for the case when the binary sequence 11100101 is applied to a PSK modulator, assuming that the line encoder and sinusoidal carrier-wave oscillator are operated from a common clock.

Problem 7.11 is as follows....

The binary sequence 11100101 is applied to an ASK modulator. The bit duration is and the sinusoidal carrier wave used to represent symbol 1 has a frequency equal to 7 MHz.

Can someone generate MatLAB plot for me for problem 7.13, comments on the code would be helpful for understanding so the more the merrier!

Answer 1

clc;

clear all;

close all;

x = [1 1 1 0 0 1 0 1] % Binary Sequence

f = 7000000; % Carrier Frequency=7MHz

br = f/2; % bit rate

bp = 1/br; % bit period

data = [];

for n=1:1:length(x)

if x(n)==1;

b=ones(1,100);

  else x(n)==0;

b=ones(1,100);

end

data=[data b];

end

t1=bp/100:bp/100:100*length(x)*(bp/100)

subplot(3,1,1);

plot(t1,bit,'linewidth',2.5);

axis([0 bp*length(x) 0 1]);

ylabel('amplitude(V)');

xlabel('time(sec)');

title('transmitted bit sequence');

%XXXXX Modulator XXXXX%

t2=bp/100:bp/100:bp;

l=length(t2);

r=[];

for (i=1:1:length(x))

if (x(i)==1)

y=cos(2*pi*f*t2);

else

y=cos(2*pi*f*t2+pi);

end

r=[r y];

end

t3=bp/99:bp/99:bp*length(x);

subplot(3,1,2);

plot(t3,r);

ylabel('amplitude(V)');

xlabel('time(sec)');

title('PSK modulated waveform');

transmitted bit sequence amplitude(V) 0.5 1.5 2 x10- time (sec) PSK modulated waveform amplitude(V) 11.5 22.5 time(sec)