Communication systems are often subject to interference from a variety of source

Question

Communication systems are often subject to interference from a variety of sources. In this project, you will use MATLAB to read a wav file, simulate the effect of narrowband interference and process the distorted signal to recover the original signal. You should write a MATLAB program that performs the following function.
Simulate the effect of interference. We will model the interference as being composed of 10 cosinusoid functions at frequencies 4500,4550,..,4950 Hz whose amplitudes are all Gaussian random variables with zero mean and variance 1/10. Play this through the speakers and observe that you can see the effect of interference. Plot the magnitude of the Fourier transform of the speech file with interference. You should see that the interference is dominant.

For remaining 1500 points, paste same answer on link below!
http://www.chegg.com/homework-help/questions-and-answers/communication-systems-often-subject-interference-variety-sources-project-use-matlab-read-w-q5313076

Explanation / Answer

%% Load Audio Data
f = load('mtlb');
Speech = f.mtlb;
Fs = f.Fs;
% You should use [Speech, Fs] = audioread('filename'); if you have an auido file

L = size(Speech,1); %Number of Data points
T = 1/Fs; %Sample Time

%% Add Distortion
DistAmp = normrnd(0,0.1,10,1); %Gaussian distortion amplitudes
DistFreq = 4500:50:4950; %Distortion Frequencies
t = (0:L-1)*T;

SpeechDist = Speech; %Initialize distorted speech
for n = 1:10
SpeechDist = SpeechDist + DistAmp(n)*cos(2*pi*DistFreq(n)*t)';
end

%% Play both original and distorted versions
fprintf(' Playing Original Recording ')
soundsc(Speech,Fs)
pause(2)
fprintf(' Playing Distroted Recording ')
soundsc(SpeechDist,Fs)

%% Calculating and Plotting Fourier Transform
NFFT = 2^nextpow2(L);
fourier = fft(SpeechDist,NFFT)/L;
f = Fs*linspace(0,1,NFFT);

plot(f,2*abs(fourier(1:NFFT)))
title('Fourier Transform of Distorted Speech Signal, y(t)')
xlabel('Frequency (Hz)')
ylabel('|Y(f)|')

% You will se 10 spikes corresponding to the 10 frequencies that we used

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