EXPT.NO.7 Amplitude Modulation and Demodulation using NumPy and Matplotlib Aim

To implement and analyze amplitude modulation (AM) using Python's NumPy and Matplotlib libraries. Apparatus Required Software: Python with NumPy and Matplotlib libraries

Hardware: Personal Computer

Theory

Amplitude Modulation (AM) is a technique used in electronic communication, primarily for transmitting information via a radio carrier wave. In AM, the amplitude of the carrier wave is varied in proportion to that of the message signal. The general form of an AM signal is:

Algorithm

Initialize Parameters: Set the values for carrier frequency, message frequency, and sampling frequency. Generate Time Axis: Create a time vector for the signal duration. Generate Message Signal: Define the message signal as a cosine wave. Generate Carrier Signal: Define the carrier signal as a cosine wave. Modulate Signal: Apply the AM formula to obtain the modulated signal. Plot the Signals: Use Matplotlib to plot the message signal, carrier signal, and modulated signal.

program:

import numpy as np
import matplotlib.pyplot as plt
Am = 4.6
Ac = 9.2
fm = 377
fc = 3770
fs = 37700
t = np.arange(0, 2/fm, 1/fs)
m = Am * np.cos(2 * np.pi * fm * t)
plt.subplot(3, 1, 1)
plt.plot(t, m)
c = Ac * np.cos(2 * np.pi * fc * t)
plt.subplot(3, 1, 2)
plt.plot(t, c)
s = (Ac + m) * np.cos(2 * np.pi * fc * t)
plt.subplot(3, 1, 3)
plt.plot(t, s)
plt.tight_layout()
plt.show()

output :

calculation:

Result

The message signal, carrier signal, and amplitude modulated (AM) signal will be displayed in separate plots. Thus AM is implemented using numPy and Matplotlib.