#!/usr/bin/env python3

import scipy.io.wavfile
from matplotlib import pyplot as plt
import numpy as np

def main():
    rate, data = scipy.io.wavfile.read("demod.wav")

    data = data - np.average(data)
    data = data / np.max(np.abs(data))

    deriv = np.abs(data[1:] - data[0:-1])

    plt.plot(deriv)
    plt.show()





if __name__ == '__main__':
    main()