Real-Time Digital Signal Processing, 2nd Edition

1. %
   
2. % Example 2.1 Sinewave generator
   
3. % This example generate 32 sine sample,
   
4. % plot it and save in sine.dat file
   
5. 
   
6. % For the book "Real Time Digital Signal Processing:
   
7. %               Fundamentals, Implementation and Application, 3rd Ed"
   
8. %               By Sen M. Kuo, Bob H. Lee, and Wenshun Tian
   
9. %               Publisher: John Wiley and Sons, Ltd
   
10. 
    
11. n = [0:31];             % Time index n
    
12. omega = 0.25*pi;        % Digital frequency
    
13. xn = 2*sin(omega*n);    % Sinewave generation
    
14. plot(n, xn, '-o');      % Samples are marked by 'o'
    
15. xlabel('Time index, n');
    
16. ylabel('Amplitude');
    
17. axis([0 31 -2 2]);                % Define ranges of plot
    
18. save sine.dat xn -ascii;% Save in ASCII data file

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1. %
   
2. % example3_7.m - MATLAB file for designing FIR filter using
   
3. %                the Fourier series method
   
4. %
   
5. 
   
6. % For the book "Real Time Digital Signal Processing:
   
7. %               Fundamentals, Implementation and Application, 3rd Ed"
   
8. %               By Sen M. Kuo, Bob H. Lee, and Wenshun Tian
   
9. %               Publisher: John Wiley and Sons, Ltd
   
10. 
    
11. omegac = 0.4*pi; % Cutoff frequency
    
12. L = 61;                     % Filter order L = 61
    
13. M = (L-1)/2;     % M
    
14. l = 0:2*M;       % Coefficient index l
    
15. h = omegac/pi*sinc(omegac*(l-M)/pi);  % Compute coefficients
    
16. omega = -pi:2*pi/200:pi;     % Frequency range
    
17. Hd = freqz(h,1,omega);       % Frequency response
    
18. plot((omega/pi),abs(Hd)),... % Use normalized frequency
    
19.     xlabel('Normalized frequency'), ylabel('Magnitude'), grid;
    
20. axis([-1 1 0 1.2]);

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1. %
   
2. % example3_8.m - Ploting magnitude responses of rectangular
   
3. %                windows
   
4. %
   
5. 
   
6. % For the book "Real Time Digital Signal Processing:
   
7. %               Fundamentals, Implementation and Application, 3rd Ed"
   
8. %               By Sen M. Kuo, Bob H. Lee, and Wenshun Tian
   
9. %               Publisher: John Wiley and Sons, Ltd
   
10. 
    
11. M = 8;                     % M = 8 (First window)
    
12. L = 2*M+1;                 % Window length
    
13. wn = [ones(1,L)];          % Fectangular window
    
14. omega = -pi:2*pi/200:pi;   % Frequency range
    
15. Hd = freqz(wn,1,omega);    % Frequency response
    
16. mag = 20*log10(abs(Hd));   % Log scale
    
17. 
    
18. M1 = 20;                   % M = 20 (Second window)
    
19. L1 = 2*M1+1;               % Window length
    
20. wn1 = [ones(1,L1)];        % Rectangular window
    
21. omega = -pi:2*pi/200:pi;   % Frequency range
    
22. Hd1 = freqz(wn1,1,omega);  % Frequency response
    
23. mag1 = 20*log10(abs(Hd1)); % Log scale
    
24. 
    
25. subplot(2,1,1), plot((omega/pi),mag), ...
    
26.     xlabel('Normalized frequency'), ylabel('Magnitude(dB)'), grid;
    
27. axis([-1 1 -40 40]);
    
28. subplot(2,1,2), plot((omega/pi),mag1), ...
    
29.     xlabel('Normalized frequency'), ylabel('Magnitude(dB)'), grid;
    
30. axis([-1 1 -40 40]);

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1. %
   
2. % example3_9.m - Designing FIR filter using Hamming window
   
3. %
   
4. 
   
5. % For the book "Real Time Digital Signal Processing:
   
6. %               Fundamentals, Implementation and Application, 3rd Ed"
   
7. %               By Sen M. Kuo, Bob H. Lee, and Wenshun Tian
   
8. %               Publisher: John Wiley and Sons, Ltd
   
9. 
   
10. omegac = 0.4*pi; % Cutoff frequency
    
11. L = 61;          % Filter order L = 61
    
12. M = (L-1)/2;     % M
    
13. l = 0:2*M;       % Coefficient index l
    
14. h = omegac/pi*sinc(omegac*(l-M)/pi);  % Compute coefficients
    
15. wn = 0.54 -0.46*cos(2*pi*l/(L-1));    % Hamming window
    
16. hwn = h.*wn;     % Windowing
    
17. omega = -pi:2*pi/200:pi;   % Frequency range
    
18. Hr = freqz(h,1,omega);     % Frequency response-Rectangular
    
19. Hd = freqz(hwn,1,omega);   % Frequency response-Hamming  
    
20. plot((omega/pi),abs(Hr),':r',(omega/pi),abs(Hd),'-b');
    
21. xlabel('Normalized frequency'), ylabel('Magnitude'), grid;
    
22. legend('Rectangular window','Hamming window')
    
23. axis([-1 1 0 1.2]);

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