import numpy as np
import scipy.signal as signal
import matplotlib.pyplot as plt

b = signal.firwin2(150, [0.0, 0.3, 0.6, 1.0], [1.0, 2.0, 0.5, 0.0])
w, h = signal.freqz(b)

plt.title('Digital filter frequency response')
plt.plot(w, np.abs(h))
plt.title('Digital filter frequency response')
plt.ylabel('Amplitude Response')
plt.xlabel('Frequency (rad/sample)')
plt.grid()
plt.show()