线性调频信号脉冲压缩和去斜处理以及加窗+PD雷达测速

%%%%%%%%%%%%%%%%%%%%%%%%窄带加窗处理%%%%%%%%%%%%%%%%%%%%%%%% %% 清除 clc;clear;close all; %% 基本参数 f0=10e9;%载频 B=10e6;%信号带宽 tp=10e-6;%脉冲宽度 fs=100e6;%采样频率 k=B/tp;%LFM系数，线性调频率 R0=3000;%初始距离 c=3e8;%光速 R=6000;% 最大距离 tau=2*R0/c;% 时延 N=round(2*R/c*fs);% 点数 fft_N=2^nextpow2(N);% 点数 t=(0:fft_N-1)/fs;% 时间 %% 信号 s=rectpuls(t-tp/2,tp).*exp(1j*pi*k*(t-tp/2).^2);%%参考信号 spectrum_s=fft(s,fft_N);%参考信号频谱 spectrum_s=fftshift(spectrum_s); sb=rectpuls(t-tp/2-tau,tp).*exp(1j*pi*k*(t-tp/2-tau).^2).*exp(-2j*pi*f0*tau);%%回波信号 %%时域加窗 sm=hamming(round(tp*fs))'.*s(1:round(tp*fs));%参考信号加窗 %%频域加窗 %找频谱的-4dB压缩点，窗函数严格与该压缩点之间的频谱对应 hamming1=[zeros(1855,1)',hamming(387)',zeros(1854,1)']; spectrum_sm=hamming1.*spectrum_s; %%脉压 fft_ssb=ifft(fft(sb).*conj(fft(s))); fft_smsb=ifft(fft(sb).*conj(fft(sm,length(sb)))); fft_spsb=ifft(fft(sb).*conj(fftshift(spectrum_sm))); %%%%%%%%%%%%%%%%%%%%%%%%%%%去斜加窗处理%%%%%%%%%%%%%%%%%%%%%%%%%%%% B=10e6;%带宽10MHz tp=10e-6;%脉宽10us u=B/tp;%LFM系数 fs=50e6;%fs>=2*B/tp*tauR0=3000; R=4500;%初始距离距离波门 c=3e8;f0=60e6;%载频 N=round(2*R/c*fs);fft_N=2^nextpow2(N);t=linspace(0,2*R/c,N); f=fs*(0:fft_N-1)/fft_N-fs/2;%从-fs/2到fs/2 %%%%%%%%%%%%%%%%%%%%%%%%%%参考信号%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Sref=exp(1i*pi*u*t.^2); %%%%%%%%%%%%%%%%%%%%%%%%%%%%回波信号%%%%%%%%%%%%%%%%%%%%%%%%%%%% Sb=rectpuls(t-2*R0/c,tp).*exp(1j*pi*u*(t-2*R0/c).^2); %%%%%%%%%%%%%%%%%%%%%%%%%%%%混频信号%%%%%%%%%%%%%%%%%%%%%%%%%%%% ssb=Sref.*conj(Sb); %%加窗 %w=hamming(502)'; %hamming=[zeros(749,1)',w-min(w),zeros(249,1)']; %hamming=abs(hamming)/max(hamming); hamming=[zeros(749,1)',hamming(502)',zeros(249,1)']; ssb0=hamming.*ssb; spectrum_ssb0=fft(ssb0,fft_N);%一维距离像 spectrum_ssb=fft(ssb,fft_N); f=f*c*tp/2/B;%瞬时频率对应的距离 figure;%%图6 plot(f,db(abs(fftshift(spectrum_ssb))/max(fftshift(spectrum_ssb)))) hold on plot(f,db(abs(fftshift(spectrum_ssb0))/max(fftshift(spectrum_ssb0))),'r') legend('未加窗',... '加窗',... 'Times New Roman','FontSize',9,'location','southeast'); grid on;% 打开网格线 set(gca,'gridlinestyle','--','GridColor','k','Gridalpha',0.2,'LineWidth',1); % 设置网格线的类型,颜色,透明度以及线宽 hold off