four_ask.py

import numpy as np
import matplotlib.pyplot as plt

BIT_DURATION = 1
MODULATION_FREQ = 3 / BIT_DURATION
N_SAMPLES = 1000
ALPHABET = ['00', '01', '10', '11']


def generate_random_sequence(length):
    random_indices = np.random.randint(0, 4, (length, ))
    return [ALPHABET[i] for i in random_indices]


def ask(arr, alphabet):
    amplitudes = [alphabet.index(e) for e in arr]
    return amplitudes


def main():
    length = int(input("Please enter the length of the signal: "))
    arr = generate_random_sequence(length)
    unipolar_arr = np.array(arr)
    ask_arr = ask(unipolar_arr, ALPHABET)
    time = np.linspace(0, unipolar_arr.size, N_SAMPLES)
    samples_per_bit = N_SAMPLES/unipolar_arr.size

    bb = np.repeat(ask_arr, samples_per_bit)

    _, ax = plt.subplots(1, 1, sharex=True, sharey=True, squeeze=True)
    ax.plot(time, bb)
    ax.set_xlabel('Time')
    ax.set_ylabel('ASK Signal')
    label = "Random numbers generated: " + str(arr)
    print(label)
    plt.text(3, 3.5, label, ha='right')
    plt.show()


if __name__ == '__main__':
    main()