www.pudn.com > digitalmodulate.zip > msk.m, change:2006-09-21,size:1210b

```clear;
clc;
b = input('Enter the Bit stream \n ');
%b = [0 1 0 1 1 1 0];

n = length(b);
t = 0:.01:n;
x = 1:1:(n+2)*100;
for i = 1:n
if (b(i) == 0)
b_p(i) = -1;
else
b_p(i) = 1;
end
for j = i:.1:i+1
bw(x(i*100:(i+1)*100)) = b_p(i);
if (mod(i,2) == 0)
bow(x(i*100:(i+1)*100)) = b_p(i);
bow(x((i+1)*100:(i+2)*100)) = b_p(i);
else
bew(x(i*100:(i+1)*100)) = b_p(i);
bew(x((i+1)*100:(i+2)*100)) = b_p(i);
end
if (mod(n,2)~= 0)
bow(x(n*100:(n+1)*100)) = -1;
bow(x((n+1)*100:(n+2)*100)) = -1;
end

end
end

bw = bw(100:end);
bew = bew(100:(n+1)*100);
bow = bow(200:(n+2)*100);

wot = 2*pi*t*(5/4);
Wt = 2*pi*t/(4*1);
st = bow.*sin(wot+(bew.*bow).*Wt);

subplot(4,1,1)
plot(t,bw)
grid on ; axis([0 n -2 +2])
subplot(4,1,2)
plot(t,bow)
grid on ; axis([0 n -2 +2])
subplot(4,1,3)
plot(t,bew)
grid on ; axis([0 n -2 +2])
subplot(4,1,4)
plot(t,st)
grid on ; axis([0 n -2 +2])
Fs=5/4;
%figure
%periodogram(st)

S = fft(st,65);
PSS = S.* conj(S) / 65;
f = 1000*(-16:16)/65;
figure%
plot(f,PSS(1:33))

```