ISAR二维成像(ISARImage.mat)

%二维成像、加窗和零填充效果
clear all
close all

c = 2.99792458e8;
load ISARImage.mat%原始数据，扫频行
bw = 5e8;
prf = 5e4;
RawData = RawData.';   %原始数据，扫频行，，转置后，列扫频
[nr,np] = size(RawData);%距离单元数128，脉冲数256
dr = c/(2*bw);              %分辨率0.3m

G1 = fftshift(fft(rngpro.',[],2),2);  %距离像转置后，列扫频、每行fft，再二维fftshift
maxvl = max(max(abs(G1)));
G1 = G1/maxvl;      %归一化

figure(1)
colormap(jet)
imagesc([-prf/2 prf/2],dr*[-nr/2 nr/2],20*log10(abs(G1)));      %运动补偿后图像
ylabel('Range (meter)')
xlabel('Doppler (Hz)')
title('ISAR Image after Motion Compensation');
axis('xy')      %xy坐标变换
colorbar
% clim = get(gca,'CLim');     %图像颜色归一化至[CLOW CHIGH]
% set(gca,'CLim',clim(2) [-40 0]);
set(gca,'CLim',[-20 0]);
drawnow

% 2-D Hamming windowing
h = hamming(nr)*hamming(np)';
Yf = RawData.*h;        %原始数据加窗，列扫频
figure(2)%加窗后原始数据的展示
imagesc(20*log10(abs(Yf)));   
ylabel('Range cells')
xlabel('Pulses')
title('ISAR Raw Data after 2-D Windowing');
axis('xy')
clim = get(gca,'CLim');
set(gca,'CLim',clim(2) [-30 10]);
drawnow

% zero padding
Yz = zeros(2*nr,2*np);
Yz(1:nr,1:np) = Yf(:,:);        %零填充

figure(3)%再零填充后的原始数据展示
imagesc(20*log10(abs(Yz)));   %
ylabel('Range cells')
xlabel('Pulses')
title('ISAR Raw Data after zero padding');
axis('xy')
clim = get(gca,'CLim');
set(gca,'CLim',clim(2) [-30 10]);
drawnow

figure(4)%原始数据，加窗和零填充后，二维fft，成像效果
G2 =fftshift(fft2(Yz),2);
maxvl = max(max(abs(G2)));
G2 = G2/maxvl;
imagesc([-prf/2 prf/2],dr*[-nr/2 nr/2],20*log10(abs(G2)));
ylabel('Range (meter)')
xlabel('Doppler (Hz)')
title('ISAR Image after Windowing and Zero-Padding');
axis('xy')
colorbar
clim = get(gca,'CLim');
set(gca,'CLim',clim(2) [-40 0]);
drawnow

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