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Ok I am trying to solve this problem, I will lay it out, then say what I've done so far, and I would appreciate if someone could help me figure out where I am going wrong. I am very new to MATLAB (using it for the first time) so I've only got the basics down so far.

Problem:

Message signal

m(t) = t for 0<=t<1

= -t+2 for 1 <= t < 2

= 0 otherwise

frequency modulates the carrier c(t)=cos(2*pi*fc*t), when fc=1000Hz. The frequency-deviation constant is kf=25.

my code:

http://img31.imageshack.us/img31/7428/equation.jpg [Broken]

my code (which gives a funky picture leading me to believe that my integral code is wrong)

Unsure what to do for these

not sure about these, suggestions?

Problem:

Message signal

m(t) = t for 0<=t<1

= -t+2 for 1 <= t < 2

= 0 otherwise

frequency modulates the carrier c(t)=cos(2*pi*fc*t), when fc=1000Hz. The frequency-deviation constant is kf=25.

**1.) Plot the message signal and its integral on two separate graphs.**my code:

2)fc=1000;

kf=25;

ts=0.0001;

fs=1/ts;

df=0.25;

t0 = -1:0.01:0;

m0 = zeros(size(t0));

t1 = 0:0.01:1;

m1 = t1;

t2 = 1:0.01:2;

m2 = -t2 +2;

t = [t0 t1 t2]; % create t and m

m = [m0 m1 m2];

plot(t,m) % plot m(t)

grid % add grid and labels to plot

xlabel('t')

title('M(t) Message Signal')

Integral code... (which i think is wrong..)

clear plot

t0 = -1:0.01:0;

im0 = zeros(size(t0));

t1 = 0:0.01:1;

im1 = t1.^2/2;

t2 = 1:0.01:2;

im2 = -t2.^2/2+2*t2;

t = [t0 t1 t2]; % create t and integral of m

im = [im0 im1 im2];

plot(t,im) % plot integral of m

grid % add grid and labels to plot

xlabel('t')

title('Integral of M(t) Message Signal')

**Plot the FM signal**http://img31.imageshack.us/img31/7428/equation.jpg [Broken]

my code (which gives a funky picture leading me to believe that my integral code is wrong)

u=cos(2*pi*fc*t+2*pi*kf*im);

plot(t,u(1:length(t)))

title('u(t)')

grid

xlabel('t')

**3) Use MATLAB's Fourier-Transform routine to compute and plot the spectra of m(t) and u(t) on separate graphs.**Unsure what to do for these

**4) Determine the modulation index, the bandwidth, and the range of the instantaneous frequency of u(t)**not sure about these, suggestions?

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