import numpy as np
-import matplotlib.pyplot as plt
-modulator_frequency = 4.0
-carrier_frequency = 40.0
-modulation_index = 1.0
-size = 44100.0 * 2
-
-time = np.arange(size) / size
-modulator = np.sin(2.0 * np.pi * modulator_frequency * time) * modulation_index
-carrier = np.sin(2.0 * np.pi * carrier_frequency * time)
-
-product = np.zeros_like(modulator)
-for i, t in enumerate(time):
- product[i] = np.sin(2. * np.pi * (carrier_frequency * t + modulator[i]))
-
-modulator = np.sin(2.0 * np.pi * modulator_frequency * time) * modulation_index
-amp = np.zeros_like(modulator)
-for i, t in enumerate(time):
- amp[i] = np.sin(2. * np.pi * (carrier_frequency * t * modulator[i]))
-plt.subplot(4, 1, 1)
-plt.title('Frequency Modulation')
-plt.plot(modulator)
-plt.ylabel('Amplitude')
-plt.xlabel('Modulator signal')
-
-plt.subplot(4, 1, 2)
-plt.plot(carrier)
-plt.ylabel('Amplitude')
-plt.xlabel('Carrier signal')
-
-plt.subplot(4, 1, 3)
-plt.plot(product)
-plt.ylabel('Amplitude')
-plt.xlabel('Output signal')
-
-plt.subplot(4, 1, 4)
-plt.plot(modulator * carrier)
-plt.ylabel('Amplitude')
-plt.xlabel('Output signal')
-plt.show()
-