Update Radar simulation

Radar simulation/single target/get_doppler.m

@@ -0,0 +1,47 @@
+function v = get_doppler(s_T, s_R)
+    global T_r delta_t c f_c velocity max_t slow_len;
+    freq_s_T = 1 / T_r;
+
+    slow_freqs = ((0:slow_len - 1) * (1 / T_r)) / slow_len;
+    range_t_slow = 1:slow_len;
+
+    num_slow = max_t / T_r;
+    s_R_slow = zeros(1, slow_len);
+    k = floor(T_r / delta_t);
+
+    init_idx = 1;
+
+    while abs(s_R(init_idx)) == 0
+        init_idx = init_idx + 1;
+    end
+
+    for i = 0:num_slow - 1
+
+        while abs(s_R(init_idx + i * k)) == 0
+            init_idx = init_idx + 1;
+        end
+
+        s_R_slow(i + 1) = s_R(init_idx + i * k);
+    end
+
+    s_R_fft = fft(s_R_slow);
+    [~, max_index_s_R] = max(s_R_fft);
+    freq_s_R = slow_freqs(max_index_s_R);
+
+    figure(2);
+    subplot(2, 1, 1);
+    plot(range_t_slow, abs(s_R_slow));
+    title(sprintf('s_R'));
+    subplot(2, 1, 2);
+    plot(slow_freqs, abs(s_R_fft));
+    title(sprintf('s_R_fft, freq = %E', freq_s_R));
+    xlabel('频率 (Hz)');
+
+    f_d = freq_s_T - freq_s_R;
+
+    fprintf("doppler_freq = %E\n\n", f_d);
+    v = (c * f_d) / (2 * f_c);
+
+    fprintf("v: %E\norigin_velocity: %E\n", v, velocity);
+
+end