Range Simulation for a Portable radar

Richard Cruz

2012 5 25

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I'm trying to simulate Range with the following scrip but is giving me the following error:

Index exceeds matrix dimensions.

Error in RangeSimulation (line 35) [Y1,I1] = max(abs(spec(Fs/2+2:Fs+1)));

Need help. Here is the code:

clc; clear all; format long e;
% Declare constants
Fs = 40000; % Sampling freruency
T = 1/Fs; % Period
osf = 100;
T0 = 100e-6;
t = (0:T/osf:T0);
w = 2 * pi * 2.4e9; % Angular frequency
fm = 50; df = 330e6;
alpha = .1; 
d = 4; % Target distance in m
c = 3e8;
delay = 2 * d / c;
lambda = c / (w / 2 / pi);
dr = c / 2 / df; % Range resolution

% Calculate range r = 2*pi*df * sawtooth(2*pi*fm*t,0.5); % r = 2*pi*df * sawtooth(2*pi*fm*t,1); Tx = cos((w+r).*t); Yx = alpha * cos((w+r).*(t-delay)); %Rx = awgn(Yx,3); % Add white Gaussian noise Rx = Yx; Sx = Tx .* Rx; tay = taylorwin(length(Sx)); %tay = hamming(length(Sx)); A = tay .* Sx'; X = fftshift(fft(A)); spec = fftshift(fft(Sx)); f = (-Fs/2:1/T0/osf:Fs/2);

% Calculate weighted-mean beat frequency %fb1 = abs(spec(Fs/2+2:Fs+1))*f(Fs/2+2:Fs+1)'; %fb = fb1 / Fs / 2; [Y1,I1] = max(abs(spec(Fs/2+2:Fs+1))); [Y2,I2] = max(abs(X(Fs/(2+2):Fs+1))); fb1 = f(Fs/2+I1); fb2 = f(Fs/2+I2);

% Plot the figure subplot(3,1,1); plot(f,abs(spec)/Y1); title('No windowing'); title('Normalized Spectrum of Mixed Signal w/ Stationary Target (R = 2 m)'); xlabel('Frequency (Hz)'); ylabel('Magnitude'); % subplot(3,1,1); plot(t,Tx); % subplot(3,1,2); plot(t,Rx); % subplot(3,1,3); plot(t,Sx); subplot(3,1,2); plot(f,abs(X)/Y2); title('With windowing'); R1 = c * fb1 / 8 / df / fm; R2 = c * fb2 / 8 / df / fm; subplot(3,1,3); title('Difference in FFTs'); plot(f,(abs(X)'/Y1)-(abs(spec)/Y1)); a1 = mean(abs(A)); a2 = mean(abs(Sx));