% The function NDFT2 computes the sinc pattern of a linear array of
% sensors. The function receives three input: the interelement spacing d,
% the array weigths a, and the zero padding desired Npad.

function NDFT2(d, a, Npad)

k  = -Npad/2 : Npad/2-1; % index
u  = pi*k/Npad; % u is a vector with elements in the range of -pi/2 to pi/2
uk = sin(u);
n  = 0:Npad-1; % n is an index
m  = 1:Npad; % m is an index

% Wavenumber K = 2*pi/landa
% d = is a fraction or a multiple of lambda.
% v = K*d*uk(m).
 
v = 2*pi*d*uk(m)';
Dn(m,n+1) = exp(j*v*n);

puk = Dn * a'; % Computing the Beampattern

% Plot of the Beampatterns
figure(1); subplot(2,1,1); plot(uk,20*log10(abs(puk)));grid on; xlabel('sin(theta)'); ylabel('Magnitude (dB)')
axis([-1 1 -100 0])
subplot(2,1,2); plot(uk,puk);grid on; xlabel('sin(theta)'); ylabel('Magnitude')
axis([-1 1 -1 1])
warning off;
% Plot the beampattern as a polar graph
figure(2); polar(u',puk); hold on; polar(-u',puk);hold off        


%  Function pattern()
%
%     The function pattern() computes and plots the beampattern of a
%     Linear Array of sensors. This function has three inputs: the number of elements in
%     the array, the pointing direction of the beam pattern (an angular
%     direction in radians), and a constant spacing between the elements of
%     the array (as fraction of the wavelenght(lambda)of the transmitted  
%     signal.  The optimum spacing between elements of the array is 0.5.
%     You must also select any of the windows presented in the menu.
%     Windowing techniques are used to reduced the sidelobes of the pattern.  
%     The list of available windows is the following:
%
%           @bartlett       - Bartlett window.
%           @barthannwin    - Modified Bartlett-Hanning window.
%           @blackman       - Blackman window.
%           @blackmanharris - Minimum 4-term Blackman-Harris window.
%           @bohmanwin      - Bohman window.
%           @chebwin        - Chebyshev window.
%           @flattopwin     - Flat Top window.
%           @gausswin       - Gaussian window.
%           @hamming        - Hamming window.
%           @hann           - Hann window.
%           @kaiser         - Kaiser window.
%           @nuttallwin     - Nuttall defined minimum 4-term Blackman-Harris window.
%           @parzenwin      - Parzen (de la Valle-Poussin) window.
%           @rectwin        - Rectangular window.
%           @tukeywin       - Tukey window.
%           @triang         - Triangular window.
%
%     For example:      pattern(21, pi/4, 0.5);
%           Plots the beampattern of an linear array with 21 elements equally spaced  
%           at a half of the wavelenght(lambda/2), and a pointing
%           direction of 45 degrees. For uniform arrays use a rectangular
%           window (rectwin).




function pattern(array_number, angular_direction, spacing)

close all
clc

N = array_number;
delta = angular_direction;
d = spacing;

Npad=1024;
n=0:N-1;

delta = 2*pi*d*sin(delta);
an=1/N*exp(j*n*delta);


for i=0:500000,
   
option = menu('Choose the desired Window', 'Bartlett', 'Barthannwin', 'Blackman', 'Blackmanharris', 'Bohmanwin', 'Chebwin', 'Flattopwin', 'Gausswin', 'Hamming', 'Hann', 'Kaiser', 'Nuttallwin', 'Parzenwin', 'Rectwin', 'Tukeywin', 'Triang', 'Exit');

switch option
   
    case 1
        close all
        clear a;
        a=an;
        a = a.*bartlett(N)';
        a(Npad)=0;
     
        NDFT2(d, a, Npad);
       
       
    case 2
        close all
        clear a;
        a=an;
        a = a.*barthannwin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);
       
       
    case 3
        close all
        clear a;
        a=an;
        a = a.*blackman(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);
       
    case 4
        close all  
        clear a;
        a=an;
        a = a.*blackmanharris(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);
       
    case 5
        close all
        clear a;
        a=an;
        a = a.*bohmanwin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);
       
    case 6
        close all
        clear a;
        a=an;
        a = a.*chebwin(N,40)';
        a(Npad)=0;

        NDFT2(d, a, Npad);
       
    case 7
        close all
        clear a;
        a=an;
        a = a.*flattopwin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);
       
    case 8
        close all
        clear a;
        a=an;
        a = a.*gausswin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 9
        close all  
        clear a;
        a=an;
        a = a.*hamming(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 10
        close all
        clear a;
        a=an;
        a = a.*hann(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 11
         close all
         clear a;
        a=an;
        a = a.*kaiser(N,1)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 12
         close all
         clear a;
        a=an;
        a = a.*nuttallwin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 13
         close all
         clear a;
        a=an;
        a = a.*parzenwin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 14
         close all
         clear a;
        a=an;
        a = a.*rectwin(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 15
         close all  
         clear a;
        a=an;
        a = a.*tukeywin(N,0)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 16
        close all
        clear a;
        a=an;
        a = a.*triang(N)';
        a(Npad)=0;

        NDFT2(d, a, Npad);

    case 17
       
        break;
             
    end
   
end