close all;
clear;clc;
%% 进行参数的初始化
f0 = 77e9; %初始频率为 77GHz
B = 3e8; % 带宽为 0.3GHz
c = 3e8; % 光速 3x10^8m/s
mu = 2e12; % 调频斜率为2MHz/us
T = B/mu; % 脉宽
Fs = 2e6; % 采样频率 2MHz
SNR = 0;% 设定噪声为0dB
R1 = 20; R2 = 50; R3 = 100;
tao1 = 2 * R1 / c;tao2 = 2 * R2 / c;tao3 = 2 * R3 / c;
t=0:1/Fs:T;
sample_dot_num = round(T * Fs);%表示采样点的个数
%% 仿真第二问
figure(1);
NFFT = 512;
fr1 = mu * tao1;
Q = exp(1j*(2*pi*fr1*t+f0*tao1));
Q = awgn(Q,SNR);
frequency = 10*log10(abs(fft(Q,NFFT)));
freq = [0:NFFT-1]/NFFT*Fs;
distance = freq *c/2/mu;
plot(distance,frequency);
xlabel('距离/m');
ylabel('幅度/dB');
title('距离20m');
%% 仿真第四问
figure(2);
NFFT = 512;
fr1 = mu * tao1;
fr2 = mu * tao2;
fr3 = mu * tao3;
Q = exp(1j*(2*pi*fr1*t+f0*tao1)) + exp(1j*(2*pi*fr2*t+f0*tao2)) + exp(1j*(2*pi*fr3*t+f0*tao3));
Q = awgn(Q,SNR);
frequency = 10*log10(abs(fft(Q,NFFT)));
freq = [0:NFFT-1]/NFFT*Fs;
distance = freq *c/2/mu;
plot(distance,frequency);
xlabel('距离/m');
ylabel('幅度/dB');
title(['距离分别为20m,50m,100m']);
%% 仿真第五问
figure(3);
NFFT = 512;
R0 = 50;
R = [50.3,51,53];
tao0 = 2 * R0 / c;
fr0 = mu * tao0;
for i=1:3
tao = 2 * R(i) / c;
fr = mu * tao;
Q = exp(1j*(2*pi*fr0*t+f0*tao0)) + exp(1j*(2*pi*fr*t+f0*tao));
Q = awgn(Q,SNR);
subplot(3,1,i);
frequency = 10*log10(abs(fft(Q,NFFT)));
freq = [0:NFFT-1]/NFFT*Fs;
distance = freq *c/2/mu;
plot(distance,frequency);
axis([20,100,0,40]);
xlabel('距离/m');
ylabel('幅度/dB');
title(['另一目标距离' , num2str(R(i)) , 'm']);
end
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