Finished ECOMMS homework 3

7th-Semester-Fall-2024/ECOMMS/homework/homework-3/homework-3.md

@@ -90,6 +90,4 @@ Frequency: 1kHz
 ### 3c
 If the RF waveform appears across a 50$\Omega$ load, determine the average power and the PEP.
 
-The average power of the signal is:
-$$\langle s^2(t) \rangle = \frac{1}{T} \int\limits_{-T/2}^{T/2} 500\cos(\omega_c t + 20\cos(\omega_1 t)) dt$$
-
+The average power and the PEP are the same: $\frac{A_c^2}{2} \times \frac{1}{50} = 2.5$kW.

7th-Semester-Fall-2024/ECOMMS/homework/homework-3/problem-3.py

@@ -0,0 +1,36 @@
+import numpy as np
+import scipy as sp
+import matplotlib.pyplot as plt
+
+f_c = 100E+6
+f_m = 1E3
+T_c = 1/f_c
+
+f_s = 1E9
+T_s = 1/f_s
+
+A_c = 500
+D_p = 100
+D_f = 1E+6
+
+omega_m = 2*np.pi*f_m
+omega_c = 2*np.pi*f_c
+
+# Time samples to 10 seconds at a samplig frequency of 8kHz
+t = np.arange(0,10*T_c,T_s)
+m_p = 0.2*np.cos(omega_m * t)
+
+m_f = -2E-5*omega_m*np.sin(omega_m * t)
+M_f = 2E-5*np.cos(omega_m*t)
+theta = D_f * M_f
+
+# The phase modulated signal
+s_p = A_c*np.cos(omega_c*t + D_p*m_p)
+s_f = A_c*np.cos(omega_c*t + theta)
+
+c = A_c*np.cos(omega_c *t)
+
+plt.plot(t, s_p, label="Phase Modulated Signal")
+plt.plot(t, s_p-c)
+#plt.plot(t, s_f, label="Frequency Modulated Signal")
+plt.show()

7th-Semester-Fall-2024/ECOMMS/labs/lab1/part2.py

@@ -2,10 +2,9 @@ import numpy as np
 import matplotlib.pyplot as plt
 import scipy as sp
 
-f_s = 8E3
-
+f_s = 10
 T_s = 1/f_s
-t = np.arange(-5,5,T_s)
+t = np.arange(0,1+T_s,T_s)
 
 f = np.linspace(0,f_s,len(t))
 omega = 2*np.pi*f
@@ -18,16 +17,9 @@ w = u(t) - u(t-0.6) + u(t-0.7) - u(t-1)
 W_c = 1j*(np.exp(-1j*omega*0.6) + np.exp(-1j*omega) - np.exp(-1j*omega*0.7) - 1)/omega
 W_d = sp.fft.fft(w)
 
-print(W_c[:10])
-print(W_d[:10])
-
-
-plt.plot(t,w)
+plt.stem(f, W_d)
+plt.xlabel("Frequency (Hz)")
 plt.show()
-
-
-plt.subplot(211)
-plt.plot(W_c)
-plt.subplot(212)
-plt.plot(W_d)
+plt.bar(t, sp.fft.ifft(W_d), T_s, align='edge')
+plt.xlabel("Time (s)")
 plt.show()