NLFM_signal.rar_NLFM_signal_nlfm_雷达_非线性调频_非线性调频信号

% 非线性调频脉冲压缩信号 clear all; close all; clc; % ========信号参数======== B=5e6; fs=40e6; Tao=10e-6; fc=10e6; dt=1/fs; N=round(Tao*fs); nlfm=zeros(N,1); ft=zeros(N,1); df=B/9999; tf=zeros(10000,1); t = 0: 1/fs: Tao-1/fs; % =========产生群延时======= for m=1:10000 tf(m,1)=(Tao/B)*(m-1)*df-(0.426*Tao/pi)*sin(2*pi*(m-1)*df/B); %海明窗 % tf(m,1)=df*(m-1)*T/B+T/2/pi*(1-K)/(1+K)*sin(-2*pi*df*(m-1)/B); %S曲线 end % =========产生调频斜率====== %通过比例的方法逐点计算出调频斜率 n=2; for i=2:10000 if tf(i,1)>dt*(n-1) ft(n,1)=df*(i-1)-(tf(i,1)-dt*(n-1))*(df/(tf(i,1)-tf(i-1,1))); n=n+1; end end %通过分段线性插值的方法计算调频斜率，在每一段应用拉格朗日插值法 % n=2; % for i=2:10000 % if tf(i,1)>dt*(n-1) % ft(n,1)=(dt*(n-1)-tf(i,1))/(tf(i-1,1)-tf(i,1))*df*(i-1)+(dt*(n-1)-tf(i-1,1))/(tf(i,1)-tf(i-1,1))*df*i; % n=n+1; % end % end % figure; % plot(ft); % title('调频斜率'); % grid on; ft=ft-B/2; %频率的范围从-B/2到B/2 fai=zeros(N,1); phs=0; for m=2:N phs=phs+1.3*dt*ft(m,1)*2*pi; fai(m,1)=phs; %相位 end for k=1:N nlfm(k,1)=exp(j*fai(k,1)); %非线性调频信号 end nlfm=nlfm.'; nlfm_fc=zeros(1,N); for i=1:N nlfm_fc(i) = nlfm(i).*exp(j*(2*pi*fc*i*1/fs)); end gi=[0:N-1]*fs/N; figure; subplot(211); plot(t*1e6,nlfm_fc),xlabel('时间 us)'),title('非线性调频信号'); subplot(212); plot(gi*1e-6,(abs(fft(nlfm_fc)))),xlabel('频率 MHz)'),title('非线性调频信号的频谱'); xlim([0,20]); % filter=conj(nlfm); % out=conv(nlfm,filter); %匹配滤波 % out=abs(out/max(abs(out))); % % figure(4) % plot(20*log10(abs(out))); % grid on