End sem 7; week 2 winter session 2025

7th-Semester-Fall-2024/ECOMMS/labs/lab2/am.py

@@ -2,7 +2,7 @@ import numpy as np
 import matplotlib.pyplot as plt
 import scipy as sp
 
-def add_noise_snr_db(s, SNR):
+def add_noise(s, SNR):
     var_s = np.cov(s)
     var_noise = var_s/(10**(SNR/10))
     noise = var_noise**0.5 * np.random.randn(len(s))
@@ -51,14 +51,6 @@ def main():
     s_am = dsb_am(m, f_c, t)
     s_sc = dsb_sc(m, f_c, t)
 
-    plt.subplot(311)
-    plt.plot(t, m, label="Message Signal")
-    plt.subplot(312)
-    plt.plot(t, s_am, label="DSB-AM Modulated Signal")
-    plt.subplot(313)
-    plt.plot(t, s_sc, label="DSB-SC Modulated Signal")
-    plt.show()
-
     m_am_demod = product_demod(s_am, f_m, f_c, f_s, t)
     m_sc_demod = product_demod(s_sc, f_m, f_c, f_s, t)
 
@@ -66,14 +58,17 @@ def main():
     plt.plot(t, m_am_demod, label="Demodulated DSB-AM Signal")
     plt.plot(t, m_sc_demod, label="Demodulated DSB-SC Signal")
     plt.legend(loc="upper right")
+    plt.savefig("demodulation-clean.png")
     plt.show()
 
     m_am_noisy_demod = product_demod(add_noise_snr_db(s_am, 3), f_m, f_c, f_s, t)
     m_sc_noisy_demod = product_demod(add_noise_snr_db(s_sc, 3), f_m, f_c, f_s, t)
 
-    plt.plot(t, m)
-    plt.plot(t, m_am_noisy_demod)
-    plt.plot(t, m_sc_noisy_demod)
+    plt.plot(t, m, label="Original Message Signal")
+    plt.plot(t, m_am_noisy_demod, label="Demodulated DSB-AM Signal With Noise")
+    plt.plot(t, m_sc_noisy_demod, label="Demodulated DSB-SC Signal With Noise")
+    plt.legend(loc="upper right")
+    plt.savefig("demodulation-noisy.png")
     plt.show()
 
 if __name__ == "__main__":