Читать книгу Inverse Synthetic Aperture Radar Imaging With MATLAB Algorithms - Caner Ozdemir - Страница 82

%--------------------------------------------------------- % This code can be used to generate Figure and Figure 2.19 %--------------------------------------------------------- clear close all fo=1e6; % choose base frequency t=0:1e-9:4e-6; tt=0:1e-9:17e-6; % choose time vector k=1.0e12; % choose chirp rate sinep=sin(2*pi*fo*t);sinep(12001:16001)=sinep; % form CW pulse sinep(17001)=0; m=sin(2*pi*(fo+k*t/2).*t); % form LFM pulse m(12001:16001)=m; m(17001)=0; %---Figure 2.19(a)------------------------------------------ plot(tt*1e6,sinep,'k','LineWidth',2); set(gca,'FontName', 'Arial', 'FontSize',14,'FontWeight','Bold'); xlabel('Time [\mus]'); ylabel('Amplitude [V]'); axis([0 17 -1.1 1.1]) %---Figure 2.19(b)------------------------------------------ plot(tt*1e6,m,'k','LineWidth',2); set(gca,'FontName', 'Arial', 'FontSize',14,'FontWeight','Bold'); xlabel('Time [\mus]'); ylabel('Amplitude [V]'); axis([0 17 -1.1 1.1]) % Frequency domain equivalent df=1/170e-6; % frequency resolution f=0:df:df*170000; % set frequency vector sinep=sin(2*pi*fo*t);sinep(170001)=0; m=sin(2*pi*(fo+k*t/2).*t); m(170001)=0; fsinep=fft(sinep)/length(t); % spectrum of CW pulse fm=fft(m)/length(t);% spectrum of LFM pulse %---Figure 2.20(a)------------------------------------------------ plot(f(1:2000)/1e6,20*log10(abs(fsinep(1:2000))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\itfrequency, MHz'); ylabel('\itAmplitude, dB'); % text(8,-10,'Single tone pulse') axis([0 12 -40 -5]) %---Figure 2.20(b)------------------------------------------------ figure plot(f(1:2000)/1e6,20*log10(abs(fm (1:2000))),'k','LineWidth',2); grid minor set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); xlabel('\itfrequency, MHz'); ylabel('\itamplitude, dB'); % text(8,-10,'Chirp pulse') axis([0 12 -40 -5])