MATLAB Examples

# Figure 13. Example Clutter Ridges with Velocity Misalignment, for β=1.

## Contents

clc; clear; close all; 

fo = 450e6; % Operating Frequency in Hz fr = 300; % PRF in Hz Tr = 1/fr; % PRI in sec. c = 299792458; % Speed of Light in m/sec. lambda = c/fo; % Operating wavelength in meters. d = lambda/2; % Interelement Spacing in meters. % Azimuth angle in degrees: phi = -180:0.25:180; Lphi = length(phi); fd = zeros(1,Lphi); 

## Platform Parameters.

beta = 1; % Beta parameter value. ha = 9e3; % Platform altitude in meters. Rc = 13e4; % (clutter) range of interest in meters. va = 50; % Platform Velocity on m/sec. psi = asin(ha/Rc); % Grazing angle at the clutter patch in rad (flat earth model). theta = psi; % Depression angle to ik-th clutter patch (flat earth model). phia = 0:15:105; % Velocity Misalignment angle in degrees. % Clutter Spatial Frequency of ik-th Clutter Patch: fsp = d/lambda*cos(theta)*sin(phi*pi/180); 

## Plot Normalized Doppler Frequency vs Spatial Frequency.

figure('NumberTitle', 'off','Name', ... 'Figure 13. Example Clutter Ridges with Velocity Misalignment, for β=1', 'Position', [50 50 1150 550]); for i=1:length(phia) % Platform Velocity for various beta parameter values: % Doppler Frequency from ik-th Clutter Patch fd = 2*va/lambda*cos(theta)*sin(phi*pi/180 + phia(i)*pi/180); % Eq. (82) % Normalized Doppler Frequency: omegac = fd*Tr; front = zeros(1,Lphi); back = zeros(1,Lphi); for k=1:Lphi if abs(phi(k)) <= 90 front(k) = omegac(k); else back(k) = omegac(k); end end zeroindfront = find(front==0); zeroindback = find(back==0); front(zeroindfront) = NaN; back(zeroindback) = NaN; subplot(2,4,i); plot(fsp,front,'.'); hold on; if i>1 plot(fsp,back,'r.'); end title(['\phi_a = ',num2str(phia(i)),'\circ']); if i==1 || i==5 ylabel('Norm. Doppler Frequency \omega_c'); end if i>4 xlabel('Spatial Frequency \vartheta_c'); end ylim([-0.5 0.5]); xlim([-0.5 0.5]); grid on; if i==8 legend('front','back','Location','Best'); end end tightfig;