global f_s T_r simu_time t start_freq end_freq c len r_0 freqs s_T s_R

f_s = 1e4;
T_r = 1 / f_s;
simu_time = 1;
t = linspace(0, simu_time, f_s);
start_freq = 0;
end_freq = 1e7;
c = 3e8;
r_0 = 8e6;

s_T = chirp(t, start_freq, simu_time, end_freq, 'linear') * 10;
len = length(s_T);
freqs = linspace(-f_s / 2, f_s / 2, len);

s_R = zeros(size(s_T));
delay = 2 * r_0 / c;
delay_samples = round(delay * len) + 1;
s_R(delay_samples:len) = 0.8 * s_T(1:len-delay_samples + 1);
s_R = awgn(s_R, 1);