import numpy as np
import matplotlib.pyplot as plt
from scipy.signal import hilbert, chirp
from scipy.io.wavfile import read


duration = 1.0
fs = 400.0
samples = int(fs * duration)
t = np.arange(samples) / fs

signal = chirp(t, 20.0, t[-1], 100.0)
signal *= (1.0 + 0.5 * np.sin(2.0 * np.pi * 3.0 * t))


a = read("hidas.wav")
signal = np.array(a[1], dtype=float)
t = [x for x in range(0, len(a[1]))]

#import pdb; pdb.set_trace()

analytic_signal = hilbert(signal)
amplitude_envelope = np.abs(analytic_signal)
instantaneous_phase = np.unwrap(np.angle(analytic_signal))
instantaneous_frequency = (np.diff(instantaneous_phase) /
                           (2.0 * np.pi) * fs)

fig = plt.figure()
ax0 = fig.add_subplot(211)
ax0.plot(t, signal, label='signal')
ax0.plot(t, amplitude_envelope, label='envelope')
ax0.set_xlabel("time in seconds")
ax0.legend()
ax1 = fig.add_subplot(212)
ax1.plot(t[1:], instantaneous_frequency)
ax1.set_xlabel("time in seconds")
ax1.set_ylim(0.0, 120.0)

plt.show()