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Helloe, I am currently trying implement a blackman window. I am simulating one dimensional echo imaging for a class project. I am going to post the code I have and hope someone can help figure out why my plot is not coming out right. My plot just seems to be alot of noise. I should be getting 5 distinct narrow pulses very simliar to a series of impulse functions. If I have omitted any key info please let me know.

clear;

tau = 1e-6; % pulse duration

alpha = 5e14; % chirp rate

B = (alpha*tau)/pi; % bandwidth in Hz

dt = 1/B; % Nyquist sampling rate

dt = dt/1.2; % guard band

xc = 1000; % mean range

x0 = 100; % plus/minus x0 is target area size

c = 3e8; % speed of wave propagation

fc = 1e9; % carrier frequency

ts = 2*(xc - x0)/c; % start sampling time

tf = 2*(xc + x0)/c + tau; % end sampling time

N = 2*ceil(0.5*(tf - ts)/dt); % number of samples, Have to do 'ceil' to get an integer

t = ts + (0:N - 1)*dt; % time array

dx = c*dt/2; % range spacing

x = xc + dx*(-N/2:N/2 - 1); % range array

% Simulation

ntarget = 5; % number of targets

xn = zeros(1, ntarget); % initialize range location

fn = xn; % initialize reflectivity

xn(1) = xc; fn(1) = 0.8; % These values are arbitrary

xn(2) = xc - 0.35*x0; fn(2) = 0.5;

xn(3) = xc + 0.50*x0; fn(3) = 0.7;

xn(4) = xc - 0.90*x0; fn(4) = 1.0;

xn(5) = xc + 0.60*x0; fn(5) = 0.9;

s = zeros(1, N); % initialize echo array

for i = 1:ntarget

td = t - 2*xn(i)/c;

%****Beginning of Window Code****

ss = fn(i)*exp(j*2*pi*fc*td + j*alpha*(td.^2)).*((td >= 0) & (td <= tau));

count = 0;

for m = 1:N

if td(m) <= 0 & td(m) <= tau

count = count + 1;

y=m;

end;

end;

% s = s + 0.1*(randn(1, N) + j*randn(1, N)); % Generate noise with 0 mean and standar deviation 1

%Now the noise is added to the measured signal and a blackman window is

%multipled

s = s + ss.*[zeros(1, y-count) blackman(count)' zeros(1, N-y)];

%****End of Window Code****

end

w=[zeros(1, y-count) blackman(count)' zeros(1, N-y)];

figure;plot(w);

sb = s.*exp(-j*2*pi*fc*t); % Baseband conversion

% Synthesize Reference Signal

td = t - (2*xc)/c;

s0 = exp(j*2*pi*fc*td + j*alpha*(td.^2)).*((td >= 0) & (td <= tau));

s0b = s0.*exp(-j*2*pi*fc*t); % Baseband conversion

% Imaging

sb = fftshift(fft(fftshift(sb)));

s0b = fftshift(fft(fftshift(s0b)));

F = (sb./s0b);

Fm = (sb.*conj(s0b));

f = fftshift(ifft(fftshift(F)));

fm = fftshift(ifft(fftshift(Fm)));

figure;

subplot(2, 1, 1);

plot(x, abs(f));

xlabel('Range');

ylabel('Magnitude');

title('Range Imaging');

subplot(2, 1, 2);

plot(x, abs(fm));

xlabel('Range');

ylabel('Magnitude');

title('Range Imaging using Match Filtering');

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# My Windows cracked?(MATLAB)

Can you offer guidance or do you also need help?

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