FFT.rar_fft_sonar

clc;clear all;close all; t=0:0.001:2.047; ff=input('請輸入BIN: (a)125,(b)250,(c)375 ：','s'); %inb=input('選擇波行進角度：0(a) or 45(b)','s'); the=45; r=rectwin(16); rr=rectwin(1024); h=hamming(16); hh=hamming(1024); switch ff case 'a' f=125; case 'b' f=250; case 'c' f=375; end thetal=the/180*pi; for them=-90:1:90; thetam=them/180*pi; for n=1:1:16 syseleo1(n,:)=sin(2*pi*125*((t+(n-1)*sin(thetal)/2/500)-(n-1)*sin(thetam)/2/125)); syseleo2(n,:)=sin(2*pi*250*((t+(n-1)*sin(thetal)/2/500)-(n-1)*sin(thetam)/2/250)); syseleo3(n,:)=sin(2*pi*375*((t+(n-1)*sin(thetal)/2/500)-(n-1)*sin(thetam)/2/375)); syseleo(n,:)=syseleo1(n,:)+syseleo2(n,:)+syseleo3(n,:); end end fr1=fft(diag(rr)*syseleo(:,513:1536)',1024)/1024; fh1=fft(diag(hh)*syseleo(:,513:1536)',1024)/1024; fr2=fft(diag(r)*fr1.',256)/256; fh2=fft(diag(h)*fh1.',256)/256; bin=f/(1000/1024)+1; k=(-128:127)/256; beamr=fr2(:,bin); beamh=fh2(:,bin); bmr=fftshift(beamr); bmh=fftshift(beamh); theta=rad2deg(asin(k*2*500/f)); bmrr=2*abs(bmr); bmhh=2*abs(bmh); ccr=20*log10(bmrr/max(bmrr)); cch=20*log10(bmhh/max(bmhh)); %bm=2*abs(bmsum); %f=linspace(-90,90,181); figure(ff*2-1); plot(k,ccr,'-b'); hold on; plot(k,cch,'-r'); axis([-0.5 0.5 -60 0]); legend('rectwin','Hamming',2); %cc=20*log10(bm/max(bm)); figure(ff*2); plot(theta,ccr,'-b'); hold on; plot(theta,cch,'-r'); axis([-90 90 -60 0]); legend('rectwin','Hamming',2); %% 512 for i=1:512; binr(:,i)=fftshift(fr2(:,i)); %binh(:,i)=fftshift(fh2(:,i)); end binrdb=20*log10(abs(binr)'); %binhdb=20*log10(abs(binh)'); [xx,yy]=meshgrid(k*256,1:512); %figure(1); %mesh(xx,yy,binrdb);colorbar;caxis([-80 0]) %axis tight; %% 三角形 fs=1000; M=1024; c=1550; d=c/500/2; for ii=1:256 for i=1:512 thetaim(i,ii)=k(ii)*c*M/d/fs/i;%(11.A.37) if abs(thetaim(i,ii))>1 ; thetaim(i,ii)=NaN; end thitamm(i,ii)=rad2deg(asin(thetaim(i,ii))); if isnan(thitamm(i,ii)); binrdb(i,ii)=NaN; end end end figure(7); mesh(xx,yy,binrdb);colorbar;caxis([-80 0]); axis tight; view(2) figure(8); mesh(thitamm,yy,binrdb);colorbar;caxis([-80 0]); axis tight; view(2)