Introduction to Radar Basics - MATLAB Simulations for Radar Systems Design - page 54

Listing 1.8. MATLAB Program Ðfig1_19.mÑ
% Use this program to reproduce Fig. 1.19 and Fig. 1.20 of text.
close all
clear all
pt = 4; % peak power in Watts
freq = 94e+9; % radar operating frequency in Hz
g = 47.0; % antenna gain in dB
sigma = 20; % radar cross section in m squared
te = 293.0; % effective noise temperature in Kelvins
b = 20e+6; % radar operating bandwidth in Hz
nf = 7.0; %noise figure in dB
loss = 10.0; % radar losses in dB
range = linspace(1.e3,12e3,1000); % range to target from 1. Km 12 Km, 1000
points
snr1 = radar_eq(pt, freq, g, sigma, te, b, nf, loss, range);
Rnewci = (94^0.25) .* range;
snrCI = snr1 + 10*log10(94); % 94 pulse coherent integration
% plot SNR versus range
figure(1)
rangekm = range ./ 1000;
plot(rangekm,snr1,'k',Rnewci./1000,snr1,'k -.')
axis([1 12 -20 45])
grid
legend('single pulse','94 pulse CI')
xlabel ('Detection range - Km');
ylabel ('SNR - dB');
% Generate Figure 1.20
snr_b10 = 10.^(snr1./10);
SNR_1 = snr_b10./(2*94) + sqrt(((snr_b10.^2) ./ (4*94*94)) + (snr_b10 ./
94)); % Equation 1.80 of text
LNCI = (1+SNR_1) ./ SNR_1; % Equation 1.78 of text
NCIgain = 10*log10(94) - 10*log10(LNCI);
Rnewnci = ((10.^(0.1*NCIgain)).^0.25) .* range;
snrnci = snr1 + NCIgain;
figure (2)
plot(rangekm,snr1,'k',Rnewnci./1000,snr1,'k -.', Rnewci./1000,snr1,'k:')
axis([1 12 -20 45])
grid
legend('single pulse','94 pulse NCI','94 pulse CI')
xlabel ('Detection range - Km');
ylabel ('SNR - dB');