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clear all;close all;clc;

f0 = 10e9;

Tp = 10e-6;

B = 10e6;

fs = 100e6;

R0 = 3000;

c = 3e8;

tr = 2*R0/c;

k = B/Tp;

N = 4096;

t = (0:N-1)/fs;

%% 发射信号

S0 = rectpuls(t-Tp/2,Tp) .* exp(1i

pi

k*(t-Tp/2).^2);

figure(1);

subplot(2,1,1);plot(t

c/2,real(S0));title(‘发射信号实部’);xlabel(‘距离/m’);

subplot(2,1,2);plot(t

c/2,imag(S0));title(‘发射信号虚部’);xlabel(‘距离/m’);

%subplot(3,1,3);plot(abs(fft(S0)));

%% 发射信号频谱

S0_fft = fft(S0,N);

%% 回波构造

S1 = rectpuls(t-tr-Tp/2,Tp) .* exp(1i

pi

k*(t-tr-Tp/2).^2) .* exp(-1i

2

pi

f0

tr);

figure(2);

subplot(2,1,1);plot(t

c/2,real(S1));title(‘回波函数实部’);xlabel(‘距离/m’);

subplot(2,1,2);plot(t

c/2,imag(S1));title(‘回波函数虚部’);xlabel(‘距离/m’);

%subplot(3,1,3);plot(abs(fft(S1)));

%% 回波频谱

f = fs/N * (-N/2:N/2 – 1);

S1_fft = fft(S1,N);

figure(3);

subplot(2,1,1);plot(abs(S1_fft));title(‘回波频谱’);xlabel(‘频率’);

subplot(2,1,2);plot(fftshift(abs(S1_fft)));title(‘回波频谱’);xlabel(‘频率’);

%% 脉冲压缩

S_F = ifft( S1_fft .* conj(S0_fft));

figure(4);

subplot(2,1,1);plot(t

c/2,abs(S_F));title(‘脉压’);xlabel(‘距离/m’);

subplot(2,1,2);plot(t

c/2,db(abs(S_F)/max(S_F)));title(‘归一化’);xlabel(‘距离/m’);

%% 频域加窗

win = hamming(410);

window = [zeros(1,1843),win’,zeros(1,1843)]; %窗矩阵

S0_fft_w = fftshift(S0_fft);

S0_fft_w = window .* S0_fft_w;

% figure(5)

% plot(f,S0_fft_w);title(‘频谱加窗’);xlabel(‘频率/Hz’);

%% 加窗后脉压

S_F_w = ifft( S1_fft .* conj(fftshift(S0_fft_w)));

figure(6);

%subplot(2,1,1);plot(t

c/2,abs(S_F_w));title(‘脉压’);xlabel(‘距离/m’);

%subplot(2,1,2);

plot(t

c/2,db(abs(S_F_w)/max(S_F_w)));title(‘频域加窗后脉压’);xlabel(‘距离/m’);ylabel(‘dB’);

% S_F_w = window .* S_F;

% figure(5);

% %hold on

% subplot(2,1,1);plot(c

t/2,abs(S_F_w));title(‘加窗’);xlabel(‘距离/m’);

% subplot(2,1,2);plot(t

c/2,db(abs(S_F_w)/max(S_F_w)));title(‘归一化’);xlabel(‘距离/m’);

%% 加窗和未加窗对比

% figure(6)

% plot(t

c/2,abs(S_F));

% hold on;

% plot(c

t/2,abs(S_F_w),‘r’);xlabel(‘距离/m’);title(‘脉压’);

% figure(7)

% plot(t

c/2,db(abs(S_F)/max(S_F)));

% hold on;

% plot(t

c/2,db(abs(S_F_w)/max(S_F_w)),‘r’);title(‘归一化’);xlabel(‘距离/m’);

figure(7)

plot(t

c/2,db(abs(S_F)/max(S_F)));

hold on

plot(t

c/2,db(abs(S_F_w)/max(S_F_w)),‘r’);title(‘频域加窗和未加窗对比’);xlabel(‘距离/m’);ylabel(‘dB’);

%% 时域加窗

S0_w = hamming(1000)’ .* S0(1:1000);

S_F_wt = ifft(S1_fft.

conj(fft(S0_w,N)));

figure(8)

plot(t

c/2,db(abs(S_F_wt)/max(S_F_wt)));

hold on

plot(t*c/2,db(abs(S_F_w)/max(S_F_w)),‘r’);title(‘时域和频域加窗对比’);xlabel(‘距离/m’);ylabel(‘dB’);

legend(‘时域’,‘频域’);

% figure(8)

% plot(t*c/2,db(abs(S_F)/max(S_F)).*window);