普通chirp信号

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频谱

 图中信号载波3.2GHz，采样率256MHz，带宽100MHz，脉宽64us

%% --------仿真数据---------------
fs=256e6;
Nr=16384;
ts = 1/fs;
fc=3.2e9;
B=100e6;
Tp=64e-6;
k = B/Tp;%调频斜率
t =-Tp/2:ts:Tp/2-ts;         %距离向时间 
f_axis = (-Nr/2:Nr/2-1)/Nr*fs;
i=1;
%chirp_idea=zeros(1,Tp*fs);
chirp_idea=exp(1j*2*pi*fc*t+1j*pi*k*t.^2);%cos(2*pi*fc*t+pi*k*t.^2)+1j*sin(2*pi*fc*t+pi*k*t.^2);
chirp_idea=cos(2*pi*fc*t-pi*k*t.^2)+1j*sin(2*pi*fc*t-pi*k*t.^2);
% for t = -Tp/2:ts:Tp/2-ts%-Tp/2:ts:Tp/2
% if(t>0)
%     chirp_idea(i)=cos(2*pi*fc*t-pi*k*t.^2)+1j*sin(2*pi*fc*t-pi*k*t.^2);
% end
% if(t<=0)
%     chirp_idea(i)=cos(2*pi*fc*t+pi*k*t.^2)+1j*sin(2*pi*fc*t+pi*k*t.^2);
% end
% i=i+1;
% end
figure(5);plot(real(chirp_idea));
figure(6);plot(chirp_idea);
figure(7);plot(f_axis/1e6,(abs((fft(chirp_idea)))));%20*log10(abs((fft(chirp_idea))))

信号是三角波调制时，频谱：